Natural Products and/or Isolated Compounds on Wound HealingView this Special Issue
African Herbal Remedies with Antioxidant Activity: A Potential Resource Base for Wound Treatment
The use of traditional herbal remedies as alternative medicine plays an important role in Africa since it forms part of primary health care for treatment of various medical conditions, including wounds. Although physiological levels of free radicals are essential to the healing process, they are known to partly contribute to wound chronicity when in excess. Consequently, antioxidant therapy has been shown to facilitate healing of such wounds. Also, a growing body of evidence suggests that, at least, part of the therapeutic value of herbals may be explained by their antioxidant activity. This paper reviews African herbal remedies with antioxidant activity with the aim of indicating potential resources for wound treatment. Firstly, herbals with identified antioxidant compounds and, secondly, herbals with proven antioxidant activity, but where the compound(s) responsible for the activity has not yet been identified, are listed. In the latter case it has been attempted to ascribe the activity to a compound known to be present in the plant family and/or species, where related activity has previously been documented for another genus of the species. Also, the tests employed to assess antioxidant activity and the potential caveats thereof during assessment are briefly commented on.
Human cells are continuously exposed to exogenous oxidants as well as to those produced endogenously during normal physiological processes. Antioxidants form part of protective mechanisms that exist in human cells to scavenge and neutralize these oxidants. Oxidants such as the reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved in several diseases [1, 2]. Antioxidant defenses are defective in these diseases and therefore it is possible to limit oxidative damage and ameliorate disease progression with antioxidant supplementation .
With reference to wounds, antioxidants play pivotal roles that consequently restore normalcy to injured skin. Basal levels of ROS and other free radicals are essential in almost all phases of the wound healing process (Figure 1) . During haemostasis, ROS regulates the constriction of blood vessels to limit loss of blood. Furthermore, ROS facilitates the migration of neutrophils and monocytes from surrounding blood vessels towards the injury site. The presence of ROS and other free radicals in the wound vicinity during the inflammatory phase of the healing process is also required for infection control and general maintenance of sterility. Finally, ROS promotes the proliferation of keratinocytes, endothelial cells, and fibroblasts, thereby enhancing angiogenesis and collagen deposition. However, uncontrolled release of ROS could cause oxidative stress, resulting in cellular and tissue damage, thereby causing delayed healing .
To keep ROS within physiological levels, antioxidants serve as electron donors, thereby preventing them from capturing electrons from other molecules which ultimately leads to their destruction . Both nonenzymatic antioxidants such as glutathione, ascorbic acid, and α-tocopherol, as well as enzymatic antioxidants like catalase and peroxiredoxin, have shown potential to normalize high ROS levels and thus stimulate healing . By normalizing ROS, antioxidants can enhance their physiological roles and thereby accelerate the wound healing process. Naturally occurring antioxidants are generally favoured over their synthetic counterparts, as the latter are suspected to cause or promote negative health effects . This has resulted in the restricted use of synthetic antioxidants in several countries .
This review provides a comprehensive list of African medicinal plants and isolated compounds with antioxidant activities, with the aim of highlighting the continent’s rich herbal resource base for possible management of wounds and allied conditions. Previous reviews have listed a number of these African medicinal plants with antioxidant properties [7–9]. The present work has therefore aimed to expand the list to include medicinal plant species with antioxidant properties that are used in different African countries including those from Madagascar and Mauritius. For the sake of inclusivity, plants that have been shown to contain compounds that hold the potential of being novel antioxidants are also considered. In addition, those with anti-inflammatory properties were also included due to an earlier observation that the anti-inflammatory activities of the same extracts could be explained, at least in part, by their antioxidant properties . Additional efforts were also made to include information, where available, on their vernacular names, their regional distribution, and medicinal use and plant parts used for these preparations or for the isolation of the antioxidant ingredient(s). Table 1 lists medicinal plants that have been investigated and have confirmed antioxidant and/or anti-inflammatory activity and that contain compounds which are known to have such activities. Table 2 on the other hand lists medicinal plants that have confirmed antioxidant activity but the compounds responsible for their antioxidant property have not yet been identified.
Many edible and culinary herbs and condiments were also included in these two tables as they were used in certain instances as medicinal herbs to treat diseases. These included fruits and seeds of Balanites aegyptiaca, leaves of Boscia senegalensis, leaves of Entada africana and seeds of Parkia biglobosa, from Niger , also leaves, seeds, and stem-bark of Mangifera indica from Benin and Burkina Faso [12, 13], leaves of Cynara scolymus from Ethiopia [14, 15], leaves of Aspalathus linearis from South Africa [16–21], leaves of Cinnamomum zeylanicum from Madagascar and Ethiopia [22–24], essential oils from the bark and leaves of Ravensara aromatica from Madagascar [23, 25], buds of Syzygium aromaticum from Madagascar , seeds of Trigonella foenumgraecum from Ethiopia and Morocco [26–28], and oils in seeds of Nigella sativa from African countries of the Mediterranean region [29–31].
2. Tests Used to Assess Antioxidant Activities of African Medicinal Plant Extracts
A variety of test systems were employed to assess the antioxidant properties of the medicinal plant extracts and compounds listed in Tables 1 and 2. A comprehensive list of the methods used in antioxidant activity determination, as well as their merits and demerits, has already been published [343–346]. The methods used in the determination of antioxidant activity of natural products and isolated compounds result in varied outcomes when the same samples are tested in different laboratories and by other researchers . Furthermore, results of different methods cannot be correlated, as contradictory results are usually obtained. Hence, although several assays are available, none of them is capable of accurately and completely determining the antioxidant activity of a test substance because of the complex nature of the redox-antioxidant system in vivo (Figure 2). Based on this complexity, antioxidants are broadly classified as (i) inhibitors of free radical formation, (ii) free radical scavengers, (iii) cellular and tissue damage repairers, and (iv) signalling messengers .
The inhibition of free radical formation could protect against oxidative damage by suppressing the formation of active ROS/RNS. This typically involves reduction or inhibition of substrates required for free radical formation such as metal ions like iron (Fe) and copper (Cu). The sequestration of these metal ions by antioxidant compounds like ellagic acid and glutathione is known to suppress formation of hydrogen peroxide (H2O2) and other free radicals [348, 349]. Furthermore, increasing evidence suggests a relationship between metal overload and several chronic diseases through the induction of oxidative stress . Therefore, inhibition of free radical formation using metal ions as targets could be useful therapeutically. Antioxidant assays designed for this purpose include the cupric and ferric reducing antioxidant power (CUPRAC/FRAP). These methods measure the ability of antioxidants to reduce cupric (Cu2+) and ferric (Fe3+) ions, respectively.
Another mechanism by which antioxidants act is through the suppression of oxidative stress by directly scavenging active free radicals. Most commonly reported antioxidant assays such as 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 2,2′-diphenyl-p-picrylhydrazyl radical (DPPH), oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), total oxyradical scavenging capacity (TOSC), and total radical antioxidant parameter (TRAP) are focused on testing the ability to scavenge free radicals. Furthermore, there are diverse cellular antioxidant assays that assess the ability of antioxidant compounds and substances to protect cells against excessive free radical generation. Such assays involve the use of a fluorescent compound such as 2,7-dichlorofluoroscein to determine the ability of test samples to quench intracellularly generated free radicals and inhibit radical formation and lipid peroxidation .
There are also numerous reports of the ability of antioxidants to repair damaged tissues and improve healing. Topical application of kojic acid and deferiprone, two compounds with the ability to scavenge free radicals, enhanced healing of wounds in rats . Also, the mitochondria-targeted antioxidant, 10-(6′-plastoquinonyl) decyltriphenylphosphonium, accelerated wound closure, stimulated epithelialization, granulation tissue formation, and vascularization, and lowered lipid peroxidation in mice . Moreover, an antioxidant peptide (cathelicidin-OA1) promoted wound healing in a mouse model with full-thickness skin wounds, accelerated reepithelialization and granulation tissue formation by enhancing the recruitment of macrophages to the wound site, and induced cell proliferation and migration . Some antioxidants have also been reported to contribute to healing by enhancing the activity of endogenous antioxidant compounds and enzymes. The induction of the nuclear factor E2-related factor 2-(Nrf2) mediated antioxidative pathway by a rhomboid family protein (RHBDF2) promoted healing of injured tissues, suggesting a relationship between antioxidant gene induction and healing . Niconyl-peptide enhanced wound healing and protected against hydrogen peroxide-induced cell death by increasing the expression of Nrf2 expression in human keratinocytes .
The most common tests used to determine the antioxidant activity of samples included the assessment of the ability to scavenge free radicals such as DPPH, ABTS+ [16, 19, 35, 62, 85, 94, 98, 99, 139, 158, 175, 184, 187, 266, 282, 302, 356–364], or the hydroxyl radicals [79, 188, 267, 365, 366], as well as the hydroperoxyl radicals by the Briggs-Rauscher reaction . The ability of the extracts to chelate metal ions was also determined as further indication of their ability to contribute in the reduction of free radicals such as the hydroxyl radical . In addition, assessment of the ability of these medicinal plant extracts to protect against lipid peroxidation was also included, which in turn was measured by the malondialdehyde-thiobarbituric acid (MDA) test [320, 367], the modified thiobarbituric acid reactive species (TBARS) assay [18, 22], or conjugated diene formation . Moreover, lipid peroxidation was assessed using the fluorescent probe, diphenyl-1-pyrenylphosphine (DPPP) , or using the inhibition of Cu(2+)-mediated oxidation of human low-density lipoprotein (LDL) [187, 367]. The ability of extracts to protect against damage to DNA using the Comet assay was also employed [114, 188].
The antioxidant capacity of the medicinal plant extracts was determined using either the TEAC or FRAP assays [11, 85, 302, 313, 321, 368]. The ability of extracts to modulate the gene expression of the antioxidant enzymes, such as Cu, Zn-superoxide dismutase (Cu, Zn-SOD), Mn-superoxide dismutase (Mn-SOD), catalase, and glutathione peroxidase (GPx), was also used as a measure of their antioxidant properties . The photochemilumiescence (PLC) assay is a more recent antioxidant capacity assessment method and was employed for the evaluation of antioxidant capacity of baobab fruit pulp extracts .
Anti-inflammatory properties of these extracts were assessed by their ability to inhibit 5-lipoxygenases [94, 370, 371] or cyclooxygenase (COX-1 and COX-2) activities [65, 275, 317, 372, 373]. Using the former  and the latter [264, 331] methodologies, respectively, a great number of South African medicinal plant extracts were screened for their anti-inflammatory properties. The effect of medicinal extracts on the biosynthesis of different prostaglandins was assessed as a measure of their anti-inflammatory effect [239, 337, 375]. Extracts of Podocarpus species were shown to inhibit the activities of the COX enzymes . Once again, using this test, the anti-inflammatory properties of the aqueous and ethanolic extracts of 39 plants used in traditional Zulu medicine were screened . The Hen’s Egg Test-Chorioallantoic Membrane (HET-CAM) assay which utilizes the CAM’s capillary system in bred hen eggs was also used to assess the anti-inflammatory activity through antiangiogenic effects of the ethanol and aqueous extracts of Drosera rotundifolia and D. madagascariensis .
The antioxidant and anti-inflammatory abilities of the herbal extracts were further assessed by evaluating their ability to control the production of ROS produced by oxidative burst in neutrophils stimulated with L-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) [21, 246]. The inhibition of neutrophils elastase was used as a measure of anti-inflammatory property and it was proposed that the presence of flavonoids such as hyperoside, quercetin, and isoquercitrin in D. rotundifolia  and five flavonoid compounds in two Polypodium species (P. decumanum and P. triseriale)  were thought to contribute to this anti-inflammatory activity. These and other in vitro tests were used to assess the antioxidant properties of three Ghanaian species: Spathodea campanulata, Commelina diffusa, and Secamone afzelii .
Inflammation is a complex mechanism with many pathways. Several extracts derived from medicinal plants have been shown to modulate or inhibit the activities of mediators of inflammation. For instance, kolaviron, a bioflavonoid compound isolated from the seeds of Garcinia kola, has been reported to possess anti-inflammatory and antioxidant activities via its effects on COX-2 and inducible nitric oxide synthase (iNOS) by inhibiting the expression of nuclear factor kappa B (NF-κB) . Quercetin is a flavonoid molecule ubiquitous in nature and functions as an antioxidant and anti-inflammatory agent. Dose- and time-dependent effects of quercetin have been investigated on proinflammatory cytokine expression and iNOS, focusing on its effects on NF-κB signal transduction pathways in lipopolysaccharide-stimulated RAW 264.7 cells by using real time polymerase chain reaction (RT-PCR) and immunoblotting. Curcumin, a yellow pigment of turmeric, has been shown to exhibit anti-inflammatory activity. Curcumin has been found effective in the treatment or control of chronic inflammatory conditions such as rheumatism, atherosclerosis, type II diabetes, and cancer . Calixto et al. reported that the anti-inflammatory action of active spice-derived components results from the disruption of the production of various inflammatory proteins (e.g., cytokines such as tumour necrosis factor-alpha (TNF-α), iNOS, and COX-2) .
Animal studies were also conducted to assess the antioxidant properties of several medicinal extracts. The antioxidant potential of Hypericum perforatum, containing many polyphenolic compounds, was evaluated on splanchnic artery occlusion (SAO) shock-mediated injury  and also against elevated brain oxidative status induced by amnestic dose of scopolamine in rats . Some medicinal plant extracts were tested for their ability to protect against carbon tetrachloride-, 2-acetylaminofluorene- (2-AAF-), and galactosamine-induced liver as well as aflatoxin B1-(AFB1-)induced genotoxicity. Using this test, it was found that an extract of Garcinia kola seeds [116, 478, 479], a decoction of Trichilia roka root , extracts of Entada africana , and Thonningia sanguinea [98, 480] possessed protective abilities. The antioxidant properties of plant extracts against potassium bromate (KBrO(3))-induced kidney damage showed the ability of G. kola seed extract to protect the kidneys .
Animal studies were also used to assess the anti-inflammatory ability of a great number of medicinal plant extracts using the carrageenan-induced rat paw oedema model. Plants investigated include seed extracts of Picralima nitida , crude methanol extract of the root of Moringa oleifera , powdered leaves and root of Mallotus oppositifolium , methanolic extract of Picralima nitida fruit , hot water extract of Alstonia boonei root-bark, Rauvolfia vomitoria root-bark, and Elaeis guineensis nuts , secondary root aqueous extract of Harpagophytum procumbens , crude extracts of Sphenocentrum jollyanum , aqueous and methanolic extracts of Hypoxis hemerocallidea corm , aqueous and methanolic extracts of Sclerocarya birrea stem-bark , aqueous extract of Mangifera indica stem-bark , aqueous extracts of Leonotis leonurus leaves , leaf extracts of Bryophyllum pinnatum , methanol extracts of the stem-bark of Alstonia boonei , aerial parts of Amaranthus caudatus , methanolic extracts of Kigelia pinnata flower , and leaf and twig extracts of Dorstenia barteri . In all of these studies, the anti-inflammatory effect against carrageenan-induced rat paw oedema was attributed to flavonoids and other polyphenolic compounds. Animal tests also employed to assess the anti-inflammatory effects of the medicinal plant extracts included inflammatory cell response such as neutrophil chemotaxis and degranulation [112, 487], antiatherosclerosis effects , and pain assessment in experimental animals .
The effect of the medicinal plants on the induction or inhibition of drug metabolizing enzymes was also studied in animals. The effect of the aqueous extract of Thonningia sanguinea on 7-ethoxyresorufin O-deethylase (EROD, CYP1A1), 7-pentoxyresorufin O-dealkylase (PROD, CYP2B1/2), 7-methoxyresorufin O-demethylase (MROD, CYP1A2), aniline hydroxylase (aniline, CYP2E1), p-nitrophenol hydroxylase (PNPH, CYP2E1), and erythromycin N-demethylase (ERDM, CYP3A1) in rat liver was found to selectively modulate CYP isoenzymes  and suppress CYP3A2 and CYP1A2 gene expression .
3. Compounds Isolated from African Medicinal Plant Extracts with Confirmed Antioxidant Activities
Several medicinal plant extracts were studied at research centres in African countries for their antioxidant properties. The major findings of these investigations have indicated that, in addition to known antioxidant compounds such as ascorbic acid in the seeds of Parkia biglobosa  and fruits pulp of Adansonia digitata , alpha-tocopherol in methanol extracts of the stems of Secamone afzelii  or from the seeds  and methanol extracts of leaves of Amaranthus caudatus , and apigenin and luteolin in aerial parts of Bulbine capitata , several other antioxidant compounds were identified. Although known antioxidant compounds such as ascorbic acid have been confirmed to promote wound healing, not all the newly identified compounds have been tested for such activity [488–491].
The identified compounds included mainly flavonoids such as flavones and flavonols, flavone and flavonol glycosides, chalcones and dihydrochalcones, and flavonones, although some anthocyanins, proanthocyanidins, and anthrones were also isolated with antioxidant properties. A wide range of plant extracts investigated have been shown to contain flavonoids. Dorstenia species are rich in flavonoids some of which are unique to this genus [67, 205], namely, prenylated flavonoids as found in Dorstenia kameruniana and twigs of D. mannii [206, 207]. Earlier studies have shown that prenylated flavonoids had antioxidant properties, which protected human LDL from oxidation . Those isolated from African medicinal plant extracts were also tested and their antioxidant properties confirmed. The antioxidant activities of three prenylated flavonoids from D. mannii (6,8-diprenyleriodictyol, dorsmanin C, 7,8-(2,2-dimethylchromeno)-6-geranyl-3,5,3′,4′-tetrahydroxyflavonol and dorsmanin F, (+)-7,8-[2′′-(1-hydroxy-1-methylethyl)-dihydrofurano]-6-prenyl-5,3′,4′-trihydroxyflavanone) against LDL oxidation and also their free radical scavenging activity have been indicated . Similarly, a diprenylated chalcone, Bartericin A, present in D. barteri leaf and twig extracts was shown to have potent antioxidant properties. It was found that this and other prenylated and geranylated chalcones were as active as the prenylated flavones and may account for the anti-inflammatory action of these extracts . Free radical scavenging activity was also confirmed for prenylated anthronoids isolated from the stem-bark of Harungana madagascariensis  and for proanthocyanidins isolated from the bark of Burkea africana . The anti-inflammatory and antioxidant activities of kolaviron, a biflavonoid isolated from a Garcinia kola seed extract to scavenge free radicals, which protect against lipid peroxidation and H2O2-induced DNA strand breaks and oxidized bases, were also reported [114, 116–119, 209]. In addition, the ability of free radical scavenging activity and ability to inhibit lipid peroxidation of Thonningianin A and Thonningianin B, ellagitannins, isolated from Thonningia sanguinea have been shown [99, 366]. The anti-inflammatory ability of Griffonianone D ((7E)-(6′′,7′′-dihydroxy-3′′,7′′-dimethyloct-2′′-enyl)oxy-4′-methoxyisoflavone), an isoflavone present in Millettia griffoniana, has been established . Prenylated anthronoids, harunmadagascarins A (8,9-dihydroxy-4,4-bis-(3,3-dimethylallyl)-6-methyl-2,3-(2,2-dimethylpyrano)anthrone and B (8,9-dihydroxy-4,4,5-tris-(3,3-dimethylallyl)-6-methyl-2,3-(2,2-dimethylpyrano)anthrone), harunganol B, and harungin anthrone from the stem-bark of Harungana madagascariensis have exhibited significant antioxidant activity . Saponins and isofuranonaphthoquinones isolated from different medicinal plant extracts showed antioxidant properties and include the saponin, Balanin 1 (3β,12β,14β,16β) cholest-5-ene-3,16-diyl bis (β-d-glucopyranoside)-12-sulphate, sterol sulfonated, Balanin 2 (3β,20S,22R,25R)-26-hydroxy-22-acetoxyfurost-5-en-3-yl-rhamnopyranosyl-(1→2)-glucopyranoside, and a furostanol saponin isolated from Balanites aegyptiaca . Isofuranonaphthoquinones isolated from the roots of Bulbine capitata, 5,8-dihydroxy-1-tigloylmethylnaphtho[2,3-c]furan-4,9-dione, 1-acetoxymethyl-8-hydroxynaphtho [2,3-c]furan-4,9-dione, and 1-acetoxymethyl-5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione possess antioxidant activities . Though none of these antioxidant compounds has been directly assessed for wound healing potential, the enhanced wound closure observed with treatment of prenylated flavonoids such as genistein  and the demonstrated effect of chalcones on the inflammation process  attest to the potential of isolated antioxidants in wound management.
4. Crude Extracts of African Medicinal Plants with Confirmed Antioxidant Activities
The antioxidant properties of a larger proportion of African medicinal plants listed in Tables 1 and 2 were tested using either aqueous or organic plant extracts. After confirming antioxidant properties, a correlation was proposed between this property and the general groups of antioxidant compounds that are present in these extracts. No further attempts were made to isolate the specific compounds that may have contributed towards this property. Flavonoids in Aloe barbadensis , chromone glycosides in A. claviflora , essential oils in Artemisia abyssinica, and Juniperus procera  as well as Helichrysum dasyanthum, H. felinum, H. excisum, and H. petiolare , proanthocyanidins in Burkea africana bark , polyphenols in extracts of Crataegus monogyna , saponins, and alkaloids in extracts of Leucosidea sericea [210, 211] are all considered as major compounds that have contributed to the antioxidant properties of these plants. Reports on a number of Barleria species, which includes B. albostellata, B. greenii, and B. prionitis, have indicated their anti-inflammatory  and antioxidant capacities . Unlike the isolated compounds, most of the plants listed for possessing antioxidant activity, including extracts of Agerantum conyzoides, Euphorbia hirta, Kigelia africana, and Nauclea latifolia, have been shown to possess wound healing ability [494–496].
Furthermore, studies have focused on screening a vast number of plants, used in a specific region, so as to determine their antioxidant properties, Mali , South Africa [19, 188, 267, 364], Cameroon [182, 313], Algeria , Ghana , Burkina Faso , Madagascar , and Mauritius , and anti-inflammatory properties, South Africa [168, 264, 374, 376] and West Africa .
5. Discussion and Conclusion
The use of traditional herbal remedies as alternative medicine plays a significant role in Africa since it features extensively in primary health care. The search for natural antioxidants, especially from plant sources, as a potential intervention for treatment of free radical mediated diseases is an important research field, especially for those in developing countries. Many polyphenols, including phenolic acids, flavonoids (anthocyanins and anthoxanthins), tannins, and lignans, are known to act as antioxidants and protect against various pathological conditions such as coronary artery disease and wounds, in addition to their anti-inflammatory, antimicrobial, and anticancer activities [214–216].
Flavonoids are a large group of compounds containing several hydroxyl groups on their ring structures and include isoflavonoids and isoflavonoid glycosides, flavones, and flavone glycosides, flavonols and flavonol glycosides, anthocyanins, chalcones and dihydrochalcones, aurones, flavonones and dihydroflavonols, and flavans and biflavonyls. To date, approximately 9000 different flavonoids have been identified from plant sources . Great interest has been dedicated to the antioxidant properties of flavonoids that may function as potent free radical scavengers, reducing agents, and protectors against peroxidation of lipids [208, 218]. Reviews have been published documenting numerous studies on antioxidant efficacy of flavonoids and phenolic compounds as well as on the relationship between their antioxidant activities, as hydrogen donating free radical scavengers, in relation to their chemical structures. The importance of the unsaturation in the C ring of quercetin compared to catechin in the increased antioxidant activity of the former has been presented [216, 219–223]. Also, the importance of the position and number of hydroxyl groups on the phenolic rings in increasing or decreasing the antioxidant properties of these compounds has been emphasized [216, 219–223].
Although many flavonoids have been isolated from different African medicinal plant extracts, the structure-activity relationship of these compounds has not yet been investigated. Recent studies have also shown that some flavonoids are modulators of proinflammatory gene expression, thus leading to the attenuation of the inflammatory response . Examples of these include the lipophilic flavones and flavonols 5,7-dihydroxy-2′,3′,4′,5′-tetramethoxyflavone, 5,4′-dihydroxy-7,2′,3′,5′-tetramethoxyflavone, and 5,7,4′-trihydroxy-2′,3′,5′-trimethoxyflavone isolated from Psiadia punctulata  and Dinklagin B and C isolated from Dorstenia dinklagei . Isolated flavone and flavonol glycosides include kaempferide 3-O-beta-xylosyl (1→2)-beta-glucoside, kaempferol 3-O-alpha-rhamnoside-7,4′-di-O-beta-galactoside, kaempferol 3,7,4′-tri-O-beta-glucoside and quercetin 3-O-[alpha-rhamnosyl (1→6)] [beta-glucosyl (1→2)]-beta-glucoside-7-O-alpha-rhamnoside from Warburgia ugandensis, and quercetin-7,4′-disulphate from Alchornea laxiflora . Flavanones and dihydroflavonols include dorsmanin I and J and epidorsmanin F and G isolated from Dorstenia mannii  and Dinklagins A, isolated from the twigs of Dorstenia dinklagei  and two flavones isolated from the twigs of Eriosema robustum  and 1α,3β-dihydroxy-12-oleanen-29-oic (1), 1-hydroxy-12-olean-30-oic acid (2), 3,30-dihydroxyl-12-oleanen-22-one (3), and 1,3,24-trihydroxyl-12-olean-29-oic acid (4), a new pentacyclic triterpenoid (1α, 23-dihydroxy-12-oleanen-29-oic acid-3β-O-2,4-di-acetyl-l-rhamnopyranoside) (5) from Combretum imberbe . Anthocyanins isolated include the cyanidins 3-O-(2′′-galloyl-β-galactopyranoside) and 3-O-(2′′-galloyl-6′′-O-α-rhamnopyranosyl-β-galactopyranoside) from Acalypha hispida  and cyanidin 3-O-β-D-glucopyranoside and cyanidin 3-O-(2-O-β-D-xylopyranosyl)-β-D-glucopyranoside from Hibiscus sabdariffa . When revising the literature, it became apparent that even though most of these medicinal plants and compounds have confirmed antioxidant activity, not many of them have been screened for wound healing potential. As there is an association between antioxidative therapy and wound healing, research in this direction is as imminent as it is important. Furthermore, structure-activity studies on the isolated compounds from African medicinal extracts will be of great interest.
Antioxidants may exert their protective effects via different mechanisms at different stages of the oxidation process. There are those that are able to inhibit the production of free radicals via their ability to chelate transition metal ions and those that are able to quench and stabilise free radicals [229, 230]. Additionally, they are further subdivided into categories according to their functions . Such classification of the newly isolated antioxidant compounds from African medicinal plant extracts is warranted to better understand their antioxidant properties.
It should be noted that the antioxidant activity of the extracts and compounds listed in this review was mostly determined using either single assays or in vitro analysis. It is therefore possible that some of these extracts and compounds may not show antioxidant activity when alternative testing methods are used. Furthermore, although in vivo studies are encouraged, most studies cited used in vitro assays. As antioxidant activity in vitro does not necessarily translate to activity in vivo, due to pharmacokinetic and pharmacodynamic processes that occurs in vivo, it is possible that samples may not be active when tested in animals. Activity of such samples should therefore be confirmed using animal models.
Additionally, attempts should be made to identify the compounds responsible for the proven antioxidant properties where not yet done, and in cases where they have been isolated, their wound healing properties should be investigated. If the activity of the compounds and plants identified in this review is confirmed in vivo, they could serve as viable sources for the treatment of wounds in future.
Conflicts of Interest
The authors declare that they have no conflicts of interest.
C. Dunnill, T. Patton, J. Brennan et al., “Reactive oxygen species (ROS) and wound healing: the functional role of ROS and emerging ROS-modulating technologies for augmentation of the healing process,” International Wound Journal, vol. 12, no. 6, pp. 1–8, 2015.View at: Publisher Site | Google Scholar
E. Moasser, N. Azarpira, A. Ghorbani dalini, and B. Shirazi, “Paraoxonase 1 (PON1) gene polymorphism and haplotype analysis in type 2 diabetes mellitus: a case–control study in the south Iranian population,” International Journal of Diabetes in Developing Countries, vol. 38, no. 1, pp. 62–68, 2018.View at: Publisher Site | Google Scholar
A. Benabbou, M. B. Khaled, and A. S. Alchalabi, “Evaluation of the Efficiency of Combined and Separated Antioxidant Supplementation of Vitamin C and E on Semen Parameters in Strepto-zotocin-Induced Diabetic Male Wistar Rats,” South Asian Journal of Experimental Biology, vol. 7, no. 4, pp. 166–72, 2018.View at: Google Scholar
S. E. Atawodi, “Antioxidant potential of African medicinal plants,” African Journal of Biotechnology, vol. 4, no. 2, pp. 128–133, 2005.View at: Google Scholar
E. O. Iwalewa, L. J. McGaw, V. Naidoo, and J. N. Eloff, “Inflammation: the foundation of diseases and disorders. A review of phytomedicines of South African origin used to treat pain and inflammatory conditions,” African Journal of Biotechnology, vol. 6, no. 25, pp. 2868–2885, 2007.View at: Publisher Site | Google Scholar
R. Gebhardt, “Antioxidative and protective properties of extracts from leaves of the artichoke (Cynara scolymus L.) against hydroperoxide-induced oxidative stress in cultured rat hepatocytes,” Toxicology and Applied Pharmacology, vol. 144, no. 2, pp. 279–286, 1997.View at: Publisher Site | Google Scholar
H. Li, N. Xia, I. Brausch, Y. Yao, and U. Förstermann, “Flavonoids from artichoke (Cynara scolymus L.) up-regulate endothelial-type nitric-oxide synthase gene expression in human endothelial cells,” The Journal of Pharmacology and Experimental Therapeutics, vol. 310, no. 3, pp. 926–932, 2004.View at: Publisher Site | Google Scholar
L. Bramati, M. Minoggio, C. Gardana, P. Simonetti, P. Mauri, and P. Pietta, “Quantitative characterization of flavonoid compounds in Rooibos tea (Aspalathus linearis) by LC-UV/DAD,” Journal of Agricultural and Food Chemistry, vol. 50, no. 20, pp. 5513–5519, 2002.View at: Publisher Site | Google Scholar
J. Mancini-Filho, A. Van-Koiij, D. A. P. Mancini, F. F. Cozzolino, and R. P. Torres, “Antioxidant activity of cinnamon (cinnamomum zeylanicum, breyne) extracts,” Bollettino Chimico Farmaceutico, vol. 137, no. 11, pp. 443–447, 1998.View at: Google Scholar
R. Randhir, Y.-T. Lin, and K. Shetty, “Phenolics, their antioxidant and antimicrobial activity in dark germinated fenugreek sprouts in response to peptide and phytochemical elicitors,” Asia Pacific Journal of Clinical Nutrition, vol. 13, no. 3, pp. 295–307, 2004.View at: Google Scholar
N. Farah, H. Benghuzzi, M. Tucci, and Z. Cason, “The effects of isolated antioxidants from black seed on the cellular metabolism of A549 cells,” Biomedical Sciences Instrumentation, vol. 41, pp. 211–216, 2005.View at: Google Scholar
M. F. Ramadan, L. W. Kroh, and J.-T. Mörsel, “Radical scavenging activity of black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.), and Niger (Guizotia abyssinica Cass.) crude seed oils and oil fractions,” Journal of Agricultural and Food Chemistry, vol. 51, no. 24, pp. 6961–6969, 2003.View at: Publisher Site | Google Scholar
S. Lee, S. Do, S. Y. Kim, J. Kim, Y. Jin, and C. H. Lee, “Mass spectrometry-based metabolite profiling and antioxidant activity of Aloe vera (Aloe barbadensis Miller) in different growth stages,” Journal of Agricultural and Food Chemistry, vol. 60, no. 45, pp. 11222–11228, 2012.View at: Publisher Site | Google Scholar
X.-f. Zhang, H.-m. Wang, Y.-l. Song et al., “Isolation, structure elucidation, antioxidative and immunomodulatory properties of two novel dihydrocoumarins from Aloe vera,” Bioorganic & medicinal chemistry letters, vol. 16, no. 4, pp. 949–953, 2006.View at: Google Scholar
M. Moniruzzaman, B. Rokeya, S. Ahmed, A. Bhowmik, M. I. Khalil, and S. H. Gan, “In vitro antioxidant effects of aloe barbadensis miller extracts and the potential role of these extracts as antidiabetic and antilipidemic agents on streptozotocin-induced type 2 diabetic model rats,” Molecules, vol. 17, no. 11, pp. 12851–12867, 2012.View at: Publisher Site | Google Scholar
R. Bruni, A. Guerrini, S. Scalia, C. Romagnoli, and G. Sacchetti, “Rapid techniques for the extraction of vitamin E isomers from Amaranthus caudatus seeds: ultrasonic and supercritical fluid extraction,” Phytochemical Analysis, vol. 13, no. 5, pp. 257–261, 2002.View at: Publisher Site | Google Scholar
P. Veeru, M. P. Kishor, and M. Meenakshi, “Screening of medicinal plant extracts for antioxidant activity,” Journal of Medicinal Plants Research, vol. 3, no. 8, pp. 608–612, 2009.View at: Google Scholar
O. O. Ajileye, E. M. Obuotor, E. O. Akinkunmi, and M. A. Aderogba, “Isolation and characterization of antioxidant and antimicrobial compounds from Anacardium occidentale L. (Anacardiaceae) leaf extract,” Journal of King Saud University - Science, vol. 27, no. 3, pp. 244–252, 2015.View at: Publisher Site | Google Scholar
R. Velagapudi, O. O. Ajileye, U. Okorji, P. Jain, M. A. Aderogba, and O. A. Olajide, “Agathisflavone isolated from Anacardium occidentale suppresses SIRT1‐mediated neuroinflammation in BV2 microglia and neurotoxicity in APPS we‐transfected SH‐SY5Y cells,” Phytotherapy Research, vol. 32, no. 10, pp. 1957–1966, 2018.View at: Publisher Site | Google Scholar
A. Maiga, K. E. Malterud, D. Diallo, and B. S. Paulsen, “Antioxidant and 15-lipoxygenase inhibitory activities of the Malian medicinal plants Diospyros abyssinica (Hiern) F. White (Ebenaceae), Lannea velutina A. Rich (Anacardiaceae) and Crossopteryx febrifuga (Afzel) Benth. (Rubiaceae),” Journal of Ethnopharmacology, vol. 104, no. 1-2, pp. 132–137, 2006.View at: Publisher Site | Google Scholar
D. MacKay and A. L. Miller, “Nutritional support for wound healing,” Alternative Medicine Review, vol. 8, no. 4, pp. 359–377, 2003.View at: Google Scholar
H. Zabri, C. Kodjo, A. Benie, J. M. Bekro, and Y. A. Bekro, “Phytochemical screening and determination of flavonoids in Secamone afzelii (Asclepiadaceae) extracts,” African Journal of Pure and Applied Chemistry, vol. 2, no. 8, pp. 80–82, 2008.View at: Google Scholar
G. J. Grubben, Plant Resources of Tropical Africa (PROTA), Prota, 2008.
A. Mats' eliso and P. Karuso, “Secondary Metabolites from Basotho Medicinal Plants. II. Bulbine capitata,” Australian Journal of Chemistry, vol. 54, no. 7, pp. 427–430, 2001.View at: Google Scholar
L. V. Buwa and A. J. Afolayan, “Antimicrobial activity of some medicinal plants used for the treatment of tuberculosis in the Eastern Cape Province, South Africa,” African Journal of Biotechnology, vol. 8, no. 23, pp. 6683–6687, 2009.View at: Google Scholar
B.-E. Van Wyk, B. v. Oudtshoorn, and N. Gericke, Medicinal Plants of South Africa, Briza, 1997.
A. C. U. Lourens, D. Reddy, K. H. C. Başer, A. M. Viljoen, and S. F. van Vuuren, “In vitro biological activity and essential oil composition of four indigenous South African Helichrysum species,” Journal of Ethnopharmacology, vol. 95, no. 2-3, pp. 253–258, 2004.View at: Publisher Site | Google Scholar
L. G. Ranilla, Y.-I. Kwon, E. Apostolidis, and K. Shetty, “Phenolic compounds, antioxidant activity and in vitro inhibitory potential against key enzymes relevant for hyperglycemia and hypertension of commonly used medicinal plants, herbs and spices in Latin America,” Bioresource Technology, vol. 101, no. 12, pp. 4676–4689, 2010.View at: Publisher Site | Google Scholar
J. D. N'Guessan, A. P. Bidié, B. N. Lenta, B. Weniger, P. André, and F. Guédé-Guina, “In vitro assays for bioactivity-guided isolation of anti salmonella and antioxidant compounds in Thonningia sanguinea flowers,” African Journal of Biotechnology, vol. 6, no. 14, pp. 1685–1689, 2007.View at: Google Scholar
O. A. Binutu and B. A. Lajubutu, “Antimicrobial potentials of some plant species of the Bignoniaceae family.,” African Journal of Medicine and Medical Sciences, vol. 23, no. 3, pp. 269–273, 1994.View at: Google Scholar
J. J. Rojas, V. J. Ochoa, S. A. Ocampo, and J. F. Muñoz, “Screening for antimicrobial activity of ten medicinal plants used in Colombian folkloric medicine: a possible alternative in the treatment of non-nosocomial infections,” BMC Complementary and Alternative Medicine, vol. 6, article 2, 2006.View at: Publisher Site | Google Scholar
K. Ofori-Kwakye, A. A. Kwapong, and F. Adu, “Antimicrobial activity of extracts and topical products of the stem bark of Spathodea campanulata for wound healing,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 6, no. 2, pp. 168–174, 2009.View at: Google Scholar
M. Marzouk, A. Gamal-Eldeen, M. Mohamed, and M. El-Sayed, “Anti-proliferative and antioxidant constituents from Tecoma stans,” Zeitschrift fur Naturforschung - Section C Journal of Biosciences, vol. 61, no. 11-12, pp. 783–791, 2006.View at: Google Scholar
U. S. Akula and B. Odhav, “In vitro 5-lipoxygenase inhibition of polyphenolic antioxidants from undomesticated plants of South Africa,” Journal of Medicinal Plants Research, vol. 2, no. 9, pp. 207–212, 2008.View at: Google Scholar
E. O. Farombi, P. Møller, and L. O. Dragsted, “Ex-vivo and in vitro protective effects of kolaviron against oxygen-derived radical-induced DNA damage and oxidative stress in human lymphocytes and rat liver cells,” Cell Biology and Toxicology, vol. 20, no. 2, pp. 71–82, 2004.View at: Publisher Site | Google Scholar
E. O. Farombi, J. G. Tahnteng, A. O. Agboola, J. O. Nwankwo, and G. O. Emerole, “Chemoprevention of 2-acetylaminofluorene-induced hepatotoxicity and lipid peroxidation in rats by kolaviron—a Garcinia kola seed extract,” Food and Chemical Toxicology, vol. 38, no. 6, pp. 535–541, 2000.View at: Publisher Site | Google Scholar
S. Olaleye, E. Farombi, E. Adewoye, B. Owoyele, S. Onasanwo, and R. Elegbe, “Analgesic and anti-inflammatory effects of kaviiron (a Garcinia kola seed extract),” African journal of biomedical research, vol. 3, no. 3, pp. 171–174, 2000.View at: Google Scholar
O. A. Adaramoye, V. O. Nwaneri, K. C. Anyanwo, E. O. Farombi, and G. O. Emerole, “Possible anti-atherogenic effect of kolaviron (a Garcinia kola seed extract) in hypercholesterolaemic rats,” Clinical and Experimental Pharmacology and Physiology, vol. 32, no. 1-2, pp. 40–46, 2005.View at: Publisher Site | Google Scholar
J. O. Nwankwo, J. G. Tahnteng, and G. O. Emerole, “Inhibition of aflatoxin B1 genotoxicity in human liver-derived HepG2 cells by kolaviron biflavonoids and molecular mechanisms of action,” European Journal of Cancer Prevention, vol. 9, no. 5, pp. 351–361, 2000.View at: Publisher Site | Google Scholar
P.-C. N. Biapa, G. A. Agbor, J. E. Oben, and J. Y. Ngogang, “Phytochemical studies and antioxidant properties of four medicinal plants used in Cameroon,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 4, no. 4, pp. 495–500, 2007.View at: Google Scholar
E. O. Iwalewa, I. O. Adewale, B. J. Taiwo et al., “Effects of Harungana madagascariensis stem bark extract on the antioxidant markers in alloxan induced diabetic and carrageenan induced inflammatory disorders in rats,” Journal of Complementary and Integrative Medicine, vol. 5, no. 1, 2008.View at: Google Scholar
D. A. El-Sherbiny, A. E. Khalifa, A. S. Attia, and E. D. Eldenshary, “Hypericum perforatum extract demonstrates antioxidant properties against elevated rat brain oxidative status induced by amnestic dose of scopolamine,” Pharmacology Biochemistry & Behavior, vol. 76, no. 3-4, pp. 525–533, 2003.View at: Publisher Site | Google Scholar
A. Herold, L. Cremer, A. Calugaru et al., “Antioxidant properties of some hydroalcoholic plant extracts with antiinflammatory activity.,” Romanian Archives of Microbiology and Immunology, vol. 62, no. 3-4, pp. 217–227, 2003.View at: Google Scholar
A. Herold, L. Cremer, A. Calugaru et al., “Hydroalcoholic plant extracts with anti-inflammatory activity.,” Romanian Archives of Microbiology and Immunology, vol. 62, no. 1-2, pp. 117–129, 2003.View at: Google Scholar
D. Z. Orčić, N. M. Mimica-Dukić, M. M. Francišković, S. S. Petrović, and E. T. Jovin, “Antioxidant activity relationship of phenolic compounds in Hypericum perforatum L,” Chemistry Central Journal, vol. 5, no. 1, p. 34, 2011.View at: Google Scholar
J. N. Eloff, J. O. Famakin, and D. R. P. Katerere, “Combretum woodii (Combretaceae) leaf extracts have high activity against Gram-negative and Gram-positive bacteria,” African Journal of Biotechnology, vol. 4, no. 10, pp. 1161–1166, 2005.View at: Google Scholar
J. N. Eloff, J. O. Famakin, and D. R. P. Katerere, “Isolation of an antibacterial stilbene from Combretum woodii (Combretaceae) leaves,” African Journal of Biotechnology, vol. 4, no. 10, pp. 1167–1171, 2005.View at: Google Scholar
P. Masoko and J. N. Eloff, “Screening of twenty-four South African Combretum and six Terminalia species (Combretaceae) for antioxidant activites,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 4, no. 2, pp. 231–239, 2007.View at: Google Scholar
V. K. Zishiri, Potentising and application of a Combretum woodii leaf extract with high antibacterial and antioxidant activity, University of Pretoria, 2005.
R. Ficarra, P. Ficarra, S. Tommasini et al., “Isolation and characterization of Guiera senegalensis J.F.Gmel. active principles,” Bollettino Chimico Farmaceutico, vol. 136, no. 5, pp. 454–459, 1997.View at: Google Scholar
Ž. Maleš, M. Medić-Šarić, and F. Bucar, “Flavonoids of Guiera senegalensis J. F. GMEL. -Thin-layer Chromatography and Numerical Methods,” Croatica Chemica Acta, vol. 71, no. 1, pp. 69–79, 1998.View at: Google Scholar
J. Ezea, T. Iwuji, and M. Oguike, “Growth responses of pregnant rabbits and their litters fed Spreading day flower (Commelina diffusa Burm. F.) and rock fig (Ficus ingens Miquel) leaves,” Journal of Global Biosciences, vol. 3, no. 2, pp. 619–625, 2014.View at: Google Scholar
E. Boakye-Gyasi, G. K. Ainooson, and W. K. Abotsi, “Anti-inflammatory, antipyretic and antioxidant properties of a hydroalcoholic leaf extract of Palisota hirsuta K. Schum. (Commelinaceae),” West African Journal of Pharmacy, vol. 22, no. 1, 2011.View at: Google Scholar
S. I. Alqasoumi and M. S. Abdel-Kader, “Terpenoids from Juniperus procera with hepatoprotective activity,” Pakistan Journal of Pharmaceutical Sciences, vol. 25, no. 2, pp. 315–322, 2012.View at: Google Scholar
M. A. Sonibare and R. B. Abegunde, “In vitro antimicrobial and antioxidant analysis of Dioscorea dumetorum (Kunth) Pax and Dioscorea hirtiflora (Linn.) and their bioactive metabolites from Nigeria,” Journal of Applied Biosciences, vol. 51, pp. 3583–3590, 2012.View at: Google Scholar
M. T. Giardi, G. Rea, and B. Berra, Bio-Farms for Nutraceuticals: Functional Food and Safety Control by Biosensors, Springer Science & Business Media, 2011.
R. N. Okigbo, C. L. Anuagasi, and J. E. Amadi, “Advances in selected medicinal and aromatic plants indigenous to Africa,” Journal of Medicinal Plants Research, vol. 3, no. 2, pp. 86–95, 2009.View at: Google Scholar
G. K. Oloyede, P. A. Onocha, J. Soyinka, O. Oguntokun, and E. Thonda, “Phytochemical screening, antimicrobial and antioxidant activities of four Nigerian medicinal plants,” Annals of Biological Research, vol. 1, no. 2, pp. 114–120, 2010.View at: Google Scholar
A. Adetutu, W. A. Morgan, and O. Corcoran, “Antibacterial, antioxidant and fibroblast growth stimulation activity of crude extracts of Bridelia ferruginea leaf, a wound-healing plant of Nigeria,” Journal of Ethnopharmacology, vol. 133, no. 1, pp. 116–119, 2011.View at: Publisher Site | Google Scholar
B. Bakoma, B. Berké, K. Eklu-Gadegbeku et al., “Total phenolic content, antioxidant activity and In vitro inhibitory potential against key enzymes relevant for hyperglycemia of Bridelia ferruginea extracts,” Research Journal of Phytochemistry, vol. 6, no. 4, pp. 120–126, 2012.View at: Publisher Site | Google Scholar
T. De Bruyne, K. Cimanga, L. Pieters, M. Claeys, R. Dommisse, and A. Vlietinck, “Gallocatechin - (4'→O→7) - epigallocatechin, a new biflavonoid isolated from Bridelia ferruginea,” Natural Product Research (Formerly Natural Product Letters), vol. 11, no. 1, pp. 47–52, 1998.View at: Google Scholar
E. O. Farombi, O. Ogundipe, and J. O. Moody, “Antioxidant and anti-inflammatory activities of Mallotus oppositifolium in model systems.,” African Journal of Medicine and Medical Sciences, vol. 30, no. 3, pp. 213–215, 2001.View at: Google Scholar
V. Barku, Y. Opoku-Boahen, E. Owusu-Ansah, N. Dayie, and F. Mensah, “In-vitro assessment of antioxidant and antimicrobial activities of methanol extracts of six wound healing medicinal plants,” In-Vitro, vol. 3, no. 1, 2013.View at: Google Scholar
E. O. Farombi, “African indigenous plants with chemotherapeutic potentials and biotechnological approach to the production of bioactive prophylactic agents,” African Journal of Biotechnology, vol. 2, no. 12, pp. 662–671, 2003.View at: Google Scholar
R. Kamgang, E. Vidal Pouokam Kamgne, M. C. Fonkoua, V. Penlap N Beng, and M. Biwolé Sida, “Activities of aqueous extracts of Mallotus oppositifolium on Shigella dysenteriae A1-induced diarrhoea in rats,” Clinical and Experimental Pharmacology and Physiology, vol. 33, no. 1-2, pp. 89–94, 2006.View at: Publisher Site | Google Scholar
P. W. Sinjman, E. Joubert, D. Ferreira et al., “Antioxidant activity of the dihydrochalcones aspalathin and nothofagin and their corresponding flavones in relation to other rooibos (Aspalathus linearis) flavonoids, epigallocatechin gallate, and Trolox,” Journal of Agricultural and Food Chemistry, vol. 57, no. 15, pp. 6678–6684, 2009.View at: Publisher Site | Google Scholar
R. Johnson, D. D. Beer, P. V. Dludla, D. Ferreira, C. J. F. Muller, and E. Joubert, “Aspalathin from Rooibos ( Aspalathus linearis ): A Bioactive C -glucosyl Dihydrochalcone with Potential to Target the Metabolic Syndrome,” Planta Medica, 2018.View at: Google Scholar
R. Dave, “In vitro models for antioxidant activity evaluation and some medicinal plants possessing antioxidant properties: an overview,” African Journal of Microbiology Research, vol. 3, no. 13, pp. 981–996, 2009.View at: Google Scholar
F. Stoddard, “Novel feed and non-food uses of legumes,” Legume Futures Report, vol. 1, 2013.View at: Google Scholar
E. Joubert, E. S. Richards, J. D. Van Der Merwe, D. De Beer, M. Manley, and W. C. A. Gelderblom, “Effect of species variation and processing on phenolic composition and in vitro antioxidant activity of aqueous extracts of cyclopia spp. (Honeybush tea),” Journal of Agricultural and Food Chemistry, vol. 56, no. 3, pp. 954–963, 2008.View at: Publisher Site | Google Scholar
C. C. W. Wanjala and R. R. T. Majinda, “Isoflavone glycosides from the root wood of Erythrina latissima,” Journal of AOAC International, vol. 84, no. 2, pp. 451–453, 2001.View at: Google Scholar
K. Asres, S. Gibbons, and V. Nachname, “Anti-inflammatory activity of extracts and a saponin isolated from Melilotus elegans,” Die Pharmazie-An International Journal of Pharmaceutical Sciences, vol. 60, no. 4, pp. 310–312, 2005.View at: Google Scholar
T. Gebre-Mariam, K. Asres, M. Getie, A. Endale, R. Neubert, and P. C. Schmidt, “In vitro availability of kaempferol glycosides from cream formulations of methanolic extract of the leaves of Melilotus elegans,” European Journal of Pharmaceutics and Biopharmaceutics, vol. 60, no. 1, pp. 31–38, 2005.View at: Publisher Site | Google Scholar
S. Combes, J.-P. Finet, and D. Siri, “On the optical activity of the 3-aryl-4-hydroxycoumarin isolated from Millettia griffoniana: Molecular modelling and total synthesis,” Journal of the Chemical Society, Perkin Transactions 1, vol. 2, no. 1, pp. 38–44, 2002.View at: Google Scholar
D. Ngamga, E. Yankep, P. Tane et al., “Antiparasitic prenylated isoflavonoids from seeds of Millettia griffoniana,” Bulletin of the Chemical Society of Ethiopia, vol. 19, no. 1, pp. 75–80, 2005.View at: Google Scholar
D. A. Alabi, O. R. Akinsulire, and M. A. Sanyaolu, “Qualitative determination of chemical and nutritional composition of Parkia biglobosa (Jacq.) Benth,” African Journal of Biotechnology, vol. 4, no. 8, pp. 812–815, 2005.View at: Google Scholar
G. O. Adegoke, M. Vijay Kumar, K. Sambaiah, and B. R. Lokesh, “Inhibitory effect of Garcinia kola on lipid peroxidation in rat liver homogenate,” Indian Journal of Experimental Biology (IJEB), vol. 36, no. 9, pp. 907–910, 1998.View at: Google Scholar
A. O. Aremu, O. A. Fawole, J. C. Chukwujekwu, M. E. Light, J. F. Finnie, and J. Van Staden, “In vitro antimicrobial, anthelmintic and cyclooxygenase-inhibitory activities and phytochemical analysis of Leucosidea sericea,” Journal of Ethnopharmacology, vol. 131, no. 1, pp. 22–27, 2010.View at: Publisher Site | Google Scholar
A. O. Aremu, S. O. Amoo, A. R. Ndhlala, J. F. Finnie, and J. Van Staden, “Antioxidant activity, acetylcholinesterase inhibition, iridoid content and mutagenic evaluation of Leucosidea sericea,” Food and Chemical Toxicology, vol. 49, no. 5, pp. 1122–1128, 2011.View at: Publisher Site | Google Scholar
E. Middleton Jr., C. Kandaswami, and T. C. Theoharides, “The effects of plant flavonoids on mammalian cells: implications for inflammation, heart disease, and cancer,” Pharmacological Reviews, vol. 52, no. 4, pp. 673–751, 2000.View at: Google Scholar
M. Gordon, The mechanism of antioxidant action in vitro, Springer, Food antioxidants, 1990.
S. E. Bizimenyera, G. E. Swan, H. Chikoto, and J. N. Eloff, “Rationale for using Peltophorum africanum (Fabaceae) extracts in veterinary medicine,” Journal of the South African Veterinary Association, vol. 76, no. 2, pp. 54–58, 2005.View at: Google Scholar
N. Mongalo, “Peltophorum africanum Sond [Mosetlha]: A review of its ethnomedicinal uses, toxicology, phytochemistry and pharmacological activities,” Journal of Medicinal Plants Research, vol. 7, no. 48, pp. 3484–3491, 2013.View at: Google Scholar
L. J. Shai, S. R. Magano, S. L. Lebelo, and A. M. Mogale, “Inhibitory effects of five medicinal plants on rat alpha-glucosidase: comparison with their effects on yeast alpha-glucosidase,” Journal of Medicinal Plants Research, vol. 5, no. 13, pp. 2863–2867, 2011.View at: Google Scholar
M. Aderogba, E. Okoh, T. Adelanwa, and O. AwolowoUniv, “Antioxidant properties of the Nigerian Piliostigma species,” Journal of Biological Sciences, 2004.View at: Google Scholar
E. Bombardelli, A. Cristoni, A. Lolla et al., “Chemical and biological characterisation of Piliostigma thonningii polyphenols,” Fitoterapia, vol. 65, no. 6, pp. 493–501, 1994.View at: Google Scholar
O. M. Ighodaro, S. O. Agunbiade, J. O. Omole, and O. A. Kuti, “Evaluation of the chemical, nutritional, antimicrobial and antioxidant-vitamin profiles of Piliostigma thonningii leaves (Nigerian species),” Research Journal of Medicinal Plant, vol. 6, no. 7, pp. 537–543, 2012.View at: Publisher Site | Google Scholar
F. O. Jimoh and A. T. Oladiji, “Preliminary Studies on Piliostigma thonningii seeds: Proximate analysis, mineral composition and phytochemical screening,” African Journal of Biotechnology, vol. 4, no. 12, pp. 1439–1442, 2005.View at: Google Scholar
H. C. C. Maduka and Z. S. C. Okoye, “The effect of Sacoglottis gabonensis stem bark extract, a Nigerian alcoholic beverage additive, on the natural antioxidant defences during 2,4-dinitrophenyl hydrazine-induced membrane peroxidation in vivo,” Vascular Pharmacology, vol. 39, no. 1-2, pp. 21–31, 2002.View at: Publisher Site | Google Scholar
H. C. C. Maduka, Z. S. C. Okoye, and A. Eje, “The influence of Sacoglottis gabonensis stem bark extract and its isolate bergenin, Nigerian alcoholic beverage additives, on the metabolic and haematological side effects of 2,4-dinitrophenyl hydrazine-induced tissue damage,” Vascular Pharmacology, vol. 39, no. 6, pp. 317–324, 2002.View at: Publisher Site | Google Scholar
M. J. Van Der Merwe, K. Jenkins, E. Theron, and B. J. Van Der Walt, “Interaction of the di-catechols rooperol and nordihydroguaiaretic acid with oxidative systems in the human blood: a structure-activity relationship,” Biochemical Pharmacology, vol. 45, no. 2, pp. 303–311, 1993.View at: Publisher Site | Google Scholar
A. C. Akinmoladun, E. O. Ibukun, E. Afor, E. M. Obuotor, and E. O. Farombi, “Phytochemical constituent and antioxidant activity of extract from the leaves of Ocimum gratissimum,” Scientific Research and Essays, vol. 2, no. 5, pp. 163–166, 2007.View at: Google Scholar
R. J. Grayer, G. C. Kite, M. Abou-Zaid, and L. J. Archer, “The application of atmospheric pressure chemical ionisation liquid chromatography-mass spectrometry in the chemotaxonomic study of flavonoids: Characterisation of flavonoids from Ocimum gratissimum var. gratissimum,” Phytochemical Analysis, vol. 11, no. 4, pp. 257–267, 2000.View at: Publisher Site | Google Scholar
O. A. Odukoya, O. O. Ilori, M. O. Sofidiya, O. A. Aniunoh, B. M. Lawal, and I. O. Tade, “Antioxidant activity of Nigerian dietary spices,” Electronic Journal of Environmental, Agricultural and Food Chemistry, vol. 4, pp. 1086–1093, 2005.View at: Google Scholar
B. Prakash, R. Shukla, P. Singh, P. K. Mishra, N. K. Dubey, and R. N. Kharwar, “Efficacy of chemically characterized Ocimum gratissimum L. essential oil as an antioxidant and a safe plant based antimicrobial against fungal and aflatoxin B1 contamination of spices,” Food Research International, vol. 44, no. 1, pp. 385–390, 2011.View at: Publisher Site | Google Scholar
M. P. Germanò, V. D'Angelo, R. Sanogo, A. Morabito, S. Pergolizzi, and R. De Pasquale, “Hepatoprotective activity of Trichilia roka on carbon tetrachloride-induced liver damage in rats,” Journal of Pharmacy and Pharmacology, vol. 53, no. 11, pp. 1569–1574, 2001.View at: Publisher Site | Google Scholar
O. Nana, J. Momeni Nzangué, R. Tepongning, M. B. Ngassoum, and J. Momeni Nzangué, “Phythochemical screening, antioxIdant and antiplasmodial activities of extracts from Trichilia roka and Sapium ellipticum,” The Journal of Phytopharmacology, vol. 2, pp. 22–29, 2013.View at: Google Scholar
J. O. Moody, V. A. Robert, J. D. Connolly, and P. J. Houghton, “Anti-inflammatory activities of the methanol extracts and an isolated furanoditerpene constituent of Sphenocentrum jollyanum Pierre (Menispermaceae),” Journal of Ethnopharmacology, vol. 104, no. 1-2, pp. 87–91, 2006.View at: Publisher Site | Google Scholar
O. S. Olorunnisola, A. O. Akintola, and A. J. Afolayan, “Hepatoprotective and antioxidant effect of Sphenocentrum jollyanum (Menispermaceae) stem bark extract against CCl4- induced oxidative stress in rats,” African Journal of Pharmacy and Pharmacology, vol. 5, no. 9, pp. 1241–1246, 2011.View at: Publisher Site | Google Scholar
O. S. Olorunnisola and A. J. Afolayan, “In vivo antioxidant and biochemical evaluation of Sphenocentrum jollyanum leaf extract in P. berghei infected mice,” Pakistan Journal of Pharmaceutical Sciences, vol. 26, no. 3, pp. 445–450, 2013.View at: Google Scholar
S. I. Abdelwahab, W. S. Koko, M. M. E. Taha et al., “In vitro and in vivo anti-inflammatory activities of columbin through the inhibition of cycloxygenase-2 and nitric oxide but not the suppression of NF-κB translocation,” European Journal of Pharmacology, vol. 678, no. 1–3, pp. 61–70, 2012.View at: Publisher Site | Google Scholar
V. Kuete, B. Ngameni, A. T. Mbaveng, B. Ngadjui, J. J. M. Meyer, and N. Lall, “Evaluation of flavonoids from Dorstenia barteri for their antimycobacterial, antigonorrheal and anti-reverse transcriptase activities,” Acta Tropica, vol. 116, no. 1, pp. 100–104, 2010.View at: Publisher Site | Google Scholar
B. T. Ngadjui, J. Watchueng, F. Keumedjio, B. Ngameni, I. K. Simo, and B. M. Abegaz, “Prenylated chalcones, flavone and other constituents of the twigs of Dorstenia angusticornis and Dorstenia barteri var. subtriangularis,” Phytochemistry, vol. 66, no. 6, pp. 687–692, 2005.View at: Publisher Site | Google Scholar
B. T. Ngadjui, B. Ngameni, E. Dongo, S. F. Kouam, and B. M. Abegaz, “Prenylated and geranylated chalcones and flavones from the aerial parts of Dorstenia ciliata,” Bulletin of the Chemical Society of Ethiopia, vol. 16, no. 2, pp. 157–163, 2002.View at: Google Scholar
A. T. Mbaveng, V. Kuete, B. Ngameni et al., “Antimicrobial activities of the methanol extract and compounds from the twigs of Dorstenia mannii (Moraceae),” BMC Complementary and Alternative Medicine, vol. 12, no. 1, p. 83, 2012.View at: Google Scholar
C. Etoundi, D. Kuaté, J. Ngondi, and J. Oben, “Anti-amylase, anti-lipase and antioxidant effects of aqueous extracts of some Cameroonian spices,” Journal of Natural Products, vol. 3, no. 2010, pp. 165–171, 2010.View at: Google Scholar
S. A. Angaji, S. F. Mousavi, and E. Babapour, “Antioxidants: A few key points,” Annals of Biological Research, vol. 3, no. 8, pp. 3968–3977, 2012.View at: Google Scholar
H. Barakat, “Composition, antioxidant, antibacterial activities and mode of action of clove (Syzygium aromaticum L.) buds essential oil,” British Journal of Applied Science & Technology, vol. 4, no. 13, p. 1934, 2014.View at: Google Scholar
M. I. Nassar, A. H. Gaara, A. H. El-Ghorab et al., “Chemical constituents of clove (Syzygium aromaticum, Fam. Myrtaceae) and their antioxidant activity,” Revista Latinoamericana de Química, vol. 35, no. 3, p. 47, 2007.View at: Google Scholar
M. A. Abbasi, D. Shahwar, M. Wahab, and M. F. Saddiqui, “Antibacterial and antioxidant activities of an ethnobotanically important plant Sauromatum venosum (Ait.) Schott. of District Kotli, Azad Jammu & Kashmir,” Pakistan Journal of Botany, vol. 43, no. 1, pp. 579–585, 2011.View at: Google Scholar
A. Betancor-Fernández, A. Pérez-Gálvez, H. Sies, and W. Stahl, “Screening pharmaceutical preparations containing extracts of turmeric rhizome, artichoke leaf, devil's claw root and garlic or salmon oil for antioxidant capacity,” Journal of Pharmacy and Pharmacology, vol. 55, no. 7, pp. 981–986, 2003.View at: Publisher Site | Google Scholar
H. Göbel, A. Heinze, M. Ingwersen, U. Niederberger, and D. Gerber, “Effects of Harpagophytum procumbens LI 174 (devil's claw) on sensory, motor and vascular muscle reagibility in the treatment of unspecific back pain,” Der Schmerz, vol. 15, no. 1, pp. 10–18, 2001.View at: Publisher Site | Google Scholar
I. M. Mahomed and J. A. O. Ojewole, “Oxytocin-like effect of Harpagophytum procumbens DC [Pedaliaceae] secondary root aqueous extract on rat isolated uterus,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 3, no. 1, pp. 82–89, 2006.View at: Google Scholar
H. S. Abdillahi, J. F. Finnie, and J. Van Staden, “Anti-inflammatory, antioxidant, anti-tyrosinase and phenolic contents of four Podocarpus species used in traditional medicine in South Africa,” Journal of Ethnopharmacology, vol. 136, no. 3, pp. 496–503, 2011.View at: Publisher Site | Google Scholar
I. Meral, Z. Yener, T. Kahraman, and N. Mert, “Effect of Nigella sativa on Glucose Concentration, Lipid Peroxidation, Anti-Oxidant Defence System and Liver Damage in Experimentally-Induced Diabetic Rabbits,” Journal of Veterinary Medicine Series A, vol. 48, no. 10, pp. 593–599, 2001.View at: Publisher Site | Google Scholar
T. Bahorun, B. Gressier, F. Trotin et al., “Oxygen species scavenging activity of phenolic extracts from hawthorn fresh plant organs and pharmaceutical preparations,” Arzneimittel-Forschung/Drug Research, vol. 46, no. 11, pp. 1086–1089, 1996.View at: Google Scholar
J. Breza, O. Dzurny, A. Borowka et al., “Efficacy and acceptability of Tadenan® (Pygeum africanum extract) in the treatment of benign prostatic hyperplasia (BPH): A multicentre trial in central Europe,” Current Medical Research and Opinion, vol. 14, no. 3, pp. 127–139, 1998.View at: Publisher Site | Google Scholar
A. Ishani, R. MacDonald, D. Nelson, I. Rutks, and T. J. Wilt, “Pygeum africanum for the treatment of patients with benign prostatic hyperplasia: A systematic review and quantitative meta-analysis,” American Journal of Medicine, vol. 109, no. 8, pp. 654–664, 2000.View at: Publisher Site | Google Scholar
M. Paubert-Braquet, A. Cave, R. Hocquemiller et al., “Effect of Pygeum africanum extract on A23187-stimulated production of lipoxygenase metabolites from human polymorphonuclear cells,” Journal of Lipid Mediators and Cell Signalling, vol. 9, no. 3, pp. 285–290, 1994.View at: Google Scholar
S. O. Adeola, T. A. Yahaya, B. Hafsatu et al., “Gastro-protective effect of crossopteryx febrifuga in wistar rats,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 8, no. 3, pp. 300–306, 2011.View at: Google Scholar
V. Steenkamp, M. C. Gouws, M. Gulumian, E. E. Elgorashi, and J. Van Staden, “Studies on antibacterial, anti-inflammatory and antioxidant activity of herbal remedies used in the treatment of benign prostatic hyperplasia and prostatitis,” Journal of Ethnopharmacology, vol. 103, no. 1, pp. 71–75, 2006.View at: Publisher Site | Google Scholar
M. Lis-Balchin, S. Hart, and E. Simpson, “Buchu (Agathosma betulina and A. crenulata, Rutaceae) essential oils: Their pharmacological action on guinea-pig ileum and antimicrobial activity on microorganisms,” Journal of Pharmacy and Pharmacology, vol. 53, no. 4, pp. 579–582, 2001.View at: Publisher Site | Google Scholar
O. Ngozi, O. Samson, and S. K. Akindele, “In vitro biochemical investigations of the effects of Carica papaya and Fagara zanthoxyloides on antioxidant status and sickle erythrocytes,” African Journal of Biochemistry Research, vol. 5, no. 8, pp. 226–236, 2011.View at: Google Scholar
J. W. Ogwal-Okeng, C. Obua, and W. W. W. Anokbonggo, “Acute toxicity effects of the methanolic extract of Fagara zanthoxyloides (Lam.) root-bark,” African Health Sciences, vol. 3, no. 3, pp. 124–126, 2003.View at: Google Scholar
M. Getie, T. Gebre-Mariam, R. Rietz, and R. H. H. Neubert, “Evaluation of the release profiles of flavonoids from topical formulations of the crude extract of the leaves of Dodonea viscosa (Sapindaceae),” Die Pharmazie, vol. 57, no. 5, pp. 320–322, 2002.View at: Google Scholar
R. A. A. Mothana, S. A. A. Abdo, S. Hasson, F. M. N. Althawab, S. A. Z. Alaghbari, and U. Lindequist, “Antimicrobial, antioxidant and cytotoxic activities and phytochemical screening of some yemeni medicinal plants,” Evidence-Based Complementary and Alternative Medicine, vol. 7, no. 3, pp. 323–330, 2010.View at: Publisher Site | Google Scholar
P. M. Hanna and R. P. Mason, “Direct evidence for inhibition of free radical formation from Cu(I) and hydrogen peroxide by glutathione and other potential ligands using the EPR spin-trapping technique,” Archives of Biochemistry and Biophysics, vol. 295, no. 1, pp. 205–213, 1992.View at: Publisher Site | Google Scholar
I. A. Demyanenko, V. V. Zakharova, O. P. Ilyinskaya et al., “Mitochondria-Targeted Antioxidant SkQ1 Improves Dermal Wound Healing in Genetically Diabetic Mice,” Oxidative Medicine and Cellular Longevity, vol. 2017, 2017.View at: Google Scholar
J. Benedí, R. Arroyo, C. Romero, S. Martín-Aragón, and A. M. Villar, “Antioxidant properties and protective effects of a standardized extract of Hypericum perforatum on hydrogen peroxide-induced oxidative damage in PC12 cells,” Life Sciences, vol. 75, no. 10, pp. 1263–1276, 2004.View at: Publisher Site | Google Scholar
D. Diallo, A. Marston, C. Terreaux, Y. Toure, B. S. Paulsen, and K. Hostettmann, “Screening of malian medicinal plants for antifungal, larvicidal, molluscicidal, antioxidant and radical scavenging activities,” Phytotherapy Research, vol. 15, no. 5, pp. 401–406, 2001.View at: Publisher Site | Google Scholar
C. S. Nergard, D. Diallo, K. Inngjerdingen et al., “Medicinal use of Cochlospermum tinctorium in Mali: Anti-ulcer-, radical scavenging- and immunomodulating activities of polymers in the aqueous extract of the roots,” Journal of Ethnopharmacology, vol. 96, no. 1-2, pp. 255–269, 2005.View at: Publisher Site | Google Scholar
E. O. Farombi and I. A. Nwaokeafor, “Anti-oxidant mechanisms of kolaviron: Studies on serum lipoprotein oxidation, metal chelation and oxidative membrane damage in rats,” Clinical and Experimental Pharmacology and Physiology, vol. 32, no. 8, pp. 667–674, 2005.View at: Publisher Site | Google Scholar
F. Bucar, M. Resch, R. Bauer, M. Burits, E. Knauder, and M. Schubert-Zsilavecz, “5-methylflavasperone and rhamnetin from Guiera senegalensis and their antioxidative and 5-lipoxygenase inhibitory activity,” Die Pharmazie, vol. 30, no. 13, 1999.View at: Google Scholar
L. Krenn, G. Beyer, H. H. Pertz et al., “In vitro antispasmodic and anti-inflammatory effects of Drosera rotundifolia,” Arzneimittel-Forschung/Drug Research, vol. 54, no. 7, pp. 402–405, 2004.View at: Google Scholar
E. A. Ojo-Amaize, E. J. Nchekwube, H. B. Cottam et al., “Hypoestoxide, a natural nonmutagenic diterpenoid with antiangiogenic and antitumor activity: Possible mechanisms of action,” Cancer Research, vol. 62, no. 14, pp. 4007–4014, 2002.View at: Google Scholar
G. Chernishov, M. Arragie, and A. Etana, “Preliminary pharmacological studies on Mettere (Glinus lotoides). II. Effects upon the cardiovascular and gastrointestinal system,” Ethiopian Medical Journal, vol. 16, no. 3, pp. 105–110, 1978.View at: Google Scholar
A. E. Mengesha, Isolation, Structural Elucidation, Quantification and Formulation of the Saponins and Flavonoids of the Seeds of Glinus Lotoides, 2005.
A. Endale, B. Kammerer, T. Gebre-Mariam, and P. C. Schmidt, “Quantitative determination of the group of flavonoids and saponins from the extracts of the seeds of Glinus lotoides and tablet formulation thereof by high-performance liquid chromatography,” Journal of Chromatography A, vol. 1083, no. 1-2, pp. 32–41, 2005.View at: Publisher Site | Google Scholar
A. Endale, P. C. Schmidt, and T. Gebre-Mariam, “Standardisation and physicochemical characterisation of the extracts of seeds of Glinus lotoides,” Die Pharmazie, vol. 59, no. 1, pp. 34–38, 2004.View at: Google Scholar
M. El-Sayed, “Phytochemical investigation of Glinus lotoides growing in Egypt,” Egyptian journal of pharmaceutical sciences, vol. 38, no. 4-6, pp. 377–390, 1997.View at: Google Scholar
R. F. Atata, S. Alhassan, and S. M. Ajewole, “Effect of stem bark extracts of Enantia chloranta on some clinical isolates,” Biokemistri, vol. 15, no. 2, pp. 84–92, 2003.View at: Google Scholar
J. O. Moody, S. F. Bloomfield, and P. J. Hylands, “In-vitro evaluation of the antimicrobial activities of Enantia chlorantha Oliv. extractives,” African Journal of Medicine and Medical Sciences, vol. 24, no. 3, pp. 269–273, 1995.View at: Google Scholar
P. V. Tan, B. Nyasse, T. Dimo, P. Wafo, and B. T. Akahkuh, “Synergistic and potentiating effects of ranitidine and two new anti-ulcer compounds from Enantia chlorantha and Voacanga africana in experimental animal models,” Die Pharmazie, vol. 57, no. 6, pp. 409–412, 2002.View at: Google Scholar
A. M. Koffi, C. Kanko, H. Ramiarantsoa et al., “Essentials oils phenolic and benzenic derivatives from three Uvaria (Annonaceae) of Ivory Coast: Uvaria chamae (P. Beauv), Uvaria afzelii (Sc. Elliot), and Uvaria sp. (Aké Assi),” Comptes Rendus Chimie, vol. 7, no. 10-11, pp. 997–1002, 2004.View at: Publisher Site | Google Scholar
R. I. Uchegbu and D. E. Okwu, “An Evaluation of the Phytochemical and Nutrient Composition of the Seeds and Stem bark of Detarium senegalense Gmelin,” Journal of Natural Science Research, vol. 2, no. 5, pp. 107–111, 2012.View at: Google Scholar
S. Philipov, N. Ivanovska, R. Istatkova, M. Velikova, and P. Tuleva, “Phytochemical study and cytotoxic activity of alkaloids from Uvaria chamae P. Beauv.,” Die Pharmazie, vol. 55, no. 9, pp. 688-689, 2000.View at: Google Scholar
I. C. Ezeamuzie, M. C. Ojinnaka, E. O. Uzogara, and S. E. Oji, “Anti-inflammatory, antipyretic and anti-malarial activities of a West African medicinal plant--Picralima nitida.,” African Journal of Medicine and Medical Sciences, vol. 23, no. 1, pp. 85–90, 1994.View at: Google Scholar
J. Betti, An ethnobotanical study of medicinal plants among the Baka pygmies in the Dja biosphere reserve, Cameroon, 2004.View at: Publisher Site
N. H. Ugochukwu and N. E. Babady, “Antihyperglycemic effect of aqueous and ethanolic extracts of Gongronema latifolium leaves on glucose and glycogen metabolism in livers of normal and streptozotocin-induced diabetic rats,” Life Sciences, vol. 73, no. 15, pp. 1925–1938, 2003.View at: Publisher Site | Google Scholar
A. Togola, D. Diallo, S. Dembélé, H. Barsett, and B. S. Paulsen, “Ethnopharmacological survey of different uses of seven medicinal plants from Mali, (West Africa) in the regions Doila, Kolokani and Siby,” Journal of Ethnobiology and Ethnomedicine, vol. 1, article 7, 2005.View at: Publisher Site | Google Scholar
E. Dagne, M. Alemua, and O. Sterner, “Flavonoids from Euclea divinorum,” Bulletin of the Chemical Society of Ethiopia, vol. 7, no. 2, 1993.View at: Google Scholar
K. O. Akinyemi, O. Oladapo, C. E. Okwara, C. C. Ibe, and K. A. Fasure, “Screening of crude extracts of six medicinal plants used in South-West Nigerian unorthodox medicine for anti-methicillin resistant Staphylococcus aureus activity,” BMC Complementary and Alternative Medicine, vol. 5, 2005.View at: Google Scholar
J. O. Kokwaro, Medicinal plants of east Africa, University of Nairobi press, 2009.
S. Derese, A. Yenesew, J. O. Midiwo, M. Heydenreich, and M. G. Peter, “A new isoflavone from stem bark of Millettia dura,” Bulletin of the Chemical Society of Ethiopia, vol. 17, no. 1, pp. 113–115, 2003.View at: Google Scholar
H. Duddeck, A. Yenesew, and E. Dagne, “Isoflavonoids from Taverniera abyssinica,” Bulletin of the Chemical Society of Ethiopia, vol. 1, no. 1, p. pp, 1987.View at: Google Scholar
K. P. Latté, Phytochemische und pharmakologische Untersuchungen an Pelargonium reniforme CURT, 1999.
J. L. Ngondi, J. E. Oben, and S. R. Minka, “The effect of Irvingia gabonensis seeds on body weight and blood lipids of obese subjects in Cameroon,” Lipids in Health and Disease, vol. 4, no. 1, 12 pages, 2005.View at: Google Scholar
S. Vertuani, E. Braccioli, V. Buzzoni, and S. Manfredini, “Antioxidant capacity of Adansonia digitata fruit pulp and leaves,” Acta Phytotherapeutica, vol. 2, no. 5, pp. 2–7, 2002.View at: Google Scholar
A. H. El-Ghorab, K. F. El-Massry, F. Marx, and H. M. Fadel, “Antioxidant activity of Egyptian Eucalyptus camaldulensisvar. brevirostrisleaf extracts,” Molecular Nutrition Food Research, vol. 47, no. 1, pp. 41–45, 2003.View at: Google Scholar
J. O. Midiwo, A. Yenesew, B. Juma, K. L. Omosa, I. L. Omosa, and D. Mutisya, “Phytochemical evaluation of some Kenyan medicinal plants,” in Proceedings of the Phytochemical evaluation of some Kenyan medicinal plants. 11th NAPRECA Symposium Book of Proceedings, Antananarivo, Madagascar, 2001.View at: Google Scholar
J. O. Midiwo, N. Gikonyo, D. Wanjau, J. Matasi, and P. Waterman, “Flavonoids of Polygonum senegalense (Meisn) Part II: More surface and internal tissue flavonoid aglycones,” Bulletin of the Chemical Society of Ethiopia, vol. 6, no. 2, 1992.View at: Google Scholar
M. I. Akpanabiatu, I. B. Umoh, E. O. Udosen, A. E. Udoh, and E. E. Edet, “Rat serum electrolytes, lipid profile and cardiovascular activity on Nauclea latifolia leaf extract administration,” Indian Journal of Clinical Biochemistry, vol. 20, no. 2, pp. 29–34, 2005.View at: Publisher Site | Google Scholar
A. Gidado, D. A. Ameh, and S. E. Atawodi, “Effect of Nauclea latifolia leaves aqueous extracts on blood glucose levels of normal and alloxan-induced diabetic rats,” African Journal of Biotechnology, vol. 4, no. 1, pp. 91–93, 2005.View at: Google Scholar
E. O. Farombi, B. F. Adepoju, O. E. Ola-Davies, and G. O. Emerole, “Chemoprevention of aflatoxin B1-induced genotoxicity and hepatic oxidative damage in rats by kolaviron, a natural biflavonoid of Garcinia kola seeds,” European Journal of Cancer Prevention, vol. 14, no. 3, pp. 207–214, 2005.View at: Publisher Site | Google Scholar
J. A. O. Ojewole, “Antinociceptive, anti-inflammatory and antidiabetic properties of Hypoxis hemerocallidea Fisch. & C.A. Mey. (Hypoxidaceae) corm [‘African Potato’] aqueous extract in mice and rats,” Journal of Ethnopharmacology, vol. 103, no. 1, pp. 126–134, 2006.View at: Publisher Site | Google Scholar
J. A. O. Ojewole, “Antinociceptive, antiinflammatory and antidiabetic effects of Leonotis leonurus (L.) R. BR. (Lamiaceae) leaf aqueous extract in mice and rats,” Methods and Findings in Experimental and Clinical Pharmacology, vol. 27, no. 4, pp. 257–264, 2005.View at: Publisher Site | Google Scholar
N. Kabiri, S. Asgary, H. Madani, and P. Mahzouni, “Effects of Amaranthus caudatus l. extract and lovastatin on atherosclerosis in hypercholesterolemic rabbits,” Journal of Medicinal Plants Research, vol. 4, no. 5, pp. 355–361, 2010.View at: Google Scholar
J. M. Larrosa, V. Polo, T. Ramirez, I. Pinilla, L. E. Pablo, and F. M. Honrubia, “Alpha-tocopherol derivatives and wound healing in an experimental model of filtering surgery,” Ophthalmic Surgery, Lasers & Imaging Retina, vol. 31, no. 2, pp. 131–135, 2000.View at: Google Scholar
I. Süntar, E. K. Akkol, H. Keles, E. Yesilada, and S. D. Sarker, “Exploration of the wound healing potential of Helichrysum graveolens (Bieb.) Sweet: isolation of apigenin as an active component,” Journal of Ethnopharmacology, vol. 149, no. 1, pp. 103–110, 2013.View at: Publisher Site | Google Scholar
E. I. O. Ajayi, G. Popoola, and E. Ojediran, “Wound healing potential of Nauclea latifolia and Manihot esculenta leaf extracts in type 1 diabetic rats,” African Journal of Traditional, Complementary and Alternative Medicines, vol. 13, no. 1, pp. 1–5, 2016.View at: Google Scholar