Medicinal plants are the primary raw materials used in the production of medicinal products all over the world. As a result, more study on plants with therapeutic potential is required. The tropical tree Ziziphus spina belongs to the Rhamnaceae family. Biological reports and traditional applications including management of diabetes and treatment of malaria, digestive issues, typhoid, liver complaints, weakness, skin infections, urinary disorders, obesity, diarrhoea, and sleeplessness have all been treated with different parts of Z. spina all over the globe. The plant is identified as a rich source of diverse chemical compounds. This study is a comprehensive yet detailed review of Z. spina based on major findings from around the world regarding ethnopharmacology, biological evaluation, and chemical composition. Scopus, Web of Science, BioMed Central, ScienceDirect, PubMed, Springer Link, and Google Scholar were searched to find published articles. From the 186 research articles reviewed, we revealed the leaf extract to be significant against free radicals, microbes, parasites, inflammation-related cases, obesity, and cancer. Chemically, polyphenols/flavonoids were the most reported compounds with a composition of 66 compounds out of the total 193 compounds reported from different parts of the plant. However, the safety and efficacy of Z. spina have not been wholly assessed in humans, and further well-designed clinical trials are needed to corroborate preclinical findings. The mechanism of action of the leaf extract should be examined. The standard dose and safety of the leaf should be established.

1. Introduction

People have resorted to natural sources for cures for various ailments since ancient times [1, 2]. For millennia, people throughout the world have relied on medicinal herbs or plants [3]. Even more impressively, almost 25% of modern drugs are derived from the stem of plants in some way. This shows a robust foundation for plant-derived medicines [4]. Many current medications, nutraceuticals, nutritional supplements, and pharmaceutical products are based on these compounds. Since the development of bacterial and fungal resistance and many other diseases has become an increasing concern, there has been an upsurge in interest in the therapeutic capabilities of traditional medicines. No extensive reviews of Z. spina have been found, according to our literature search. There is only one attempt to review the plants in 2012 [5]. Ethnopharmacology, origin and distribution, taxonomic, morphological, biological evaluation, and chemical composition are examined in this study, which provides a complete overview and up-to-date information on the therapeutic properties of Z. spina with emphasis on its biological activity and chemical composition.

2. Materials and Methods

2.1. Search Criteria
2.1.1. Inclusion criteria

Electronic databases such as ScienceDirect, PubMed, Wiley, Google Scholar, Hindawi, and Springer extracting valuable information from original scientific research papers were used to find articles on Z. spina. These and many more biological evaluations were utilized as key phrases in this research. These included “antifungal and antibacterial”, “anti-inflammatory”, “herbal”, and “anticancer”.

2.1.2. Exclusion criteria

Data from questionable online sources, as well as thesis reports and review publications, were excluded from this investigation (Figure 1).

3. Results and Discussion

3.1. Ethnopharmacology

For the majority of human history, people have relied on local flora to heal a broad range of maladies, both those of themselves and their domesticated animals [6]. Depending on the community’s culture and religious beliefs, some of the plants were also used for religious rituals [3]. Traditional medicine as a collection of practices and knowledge gathered from the observations and practical experiences of previous generations was described and used for the diagnosis, eradication, and prevention of physical and nonphysical sickness [7]. Ziziphus spina has been traditionally reported in different parts of the world (Figure 2) for the treatment of various ailments [8, 9]. Flowers, leaves, and roots were reported in traditionally treated stomach pain, a disorder in Malawi, Iran, and Sudan [911]. In traditional medicine and as a source of nourishment and energy, this species is well known [12]. The extract of the plant is used in the management of dandruff, wounds, and hair loss in Bahrain [13]. In Palestine, the leaves are used in the treatment of skin infections [14]. As a remedy for constipation, people in Turkey rely on the fruit’s fiber content [15]. Cough medicine in Nigeria is typically made from the roots [16]. Fruits are used in Sudan to treat diarrhoea, rheumatism, scorpion stings, malaria, and antispasmodics [8]. Decoction is made by boiling leaves and fruits in water for half an hour, and then it should be taken three times a day as an oral supplement to lower cholesterol and cancer risk. Boiling leaves and fruits in water for half an hour produces a typical decoction that is taken three times per day as an oral supplement [12]. All parts of the plants are traditionally used in the treatment and management of various ailments in different parts of the world [911].

3.1.1. Origin, Taxonomic, and Morphological Description

In southern Sudan, Ethiopia, Northern Lebanon, and Syria, the perennial Z. spina, often known as Christ’s thorn, grows [12, 17]. A number of Ziziphus species are naturally suited to dry and hot temperatures, which makes them appropriate for cultivation in tough situations with degraded soil and inadequate water supply [17]. It is a Sudanese-bred tropical evergreen tree. It may be found in every valley and plain in Israel and is generally found at low altitudes [18]. It is a spiky and hardy, tiny shrub or tree with thorns that can withstand heat and dehydration [19]. Although this plant normally matures into a tree, heavy grazing in the latter dry seasons sometimes results in it becoming a shrub instead [19]. More than 170 species of shrubs and small trees are found in warm temperate and subtropical locations of the globe [20]; for example, Ziziphus spina-christi (L.) Desf., synonymous Ziziphus spina-christi var. spina -c hristi, Rhamnus spina -c hristi L., and infraspecific taxa of Ziziphus spina-christi var. aucheri (Boiss.) Qaiser and Nazim. Up to a 45 cm trunk diameter is possible for this tree, which may grow to a height of 5–10 meters [19]. The bark is extensively fissured and yellowish brown or light grey in colour. Round or oval in shape, the crown’s thick branches stretch out widely and weep at the ends.

3.2. Biological Evaluation

Alternative medicine is based on the use of medicinal plants, which has led to the development of many novel pharmaceuticals [21]. Increasingly more than 80% of medicine was derived from plants in the nineteenth century, and the scientific revolution led to the development of the pharmaceutical business, where the manufactured pharmaceuticals became more prominent [22]. There is a greater usage of medicinal plants in the treatment of ailments since they are regarded as safe and effective pharmaceuticals, as well as having fewer side effects and costing less than other drugs [23]. Z. spina was subjected to a number of biological evaluations (Table 1).

3.2.1. Antioxidants

Antioxidant plant-based medicine formulations are used to prevent and cure complicated illnesses such as atherosclerosis, stroke, diabetes, Alzheimer’s disease, and other neurological disorders [150]. In the human body and food system, free radical reactions occur. In the form of reactive oxygen and nitrogen species, free radicals are a natural element of physiology. The hunt for antioxidants from natural sources has got a lot of attention, and researchers are working hard to find chemicals that may replace synthetic antioxidants [151]. The potential capability of Z. spina was evaluated using animal models, DPPH and β-carotene-linoleic acid, FRAP, ribosomal degradation test, SRSA, TRPA, ABTS, Rancimat, and many more procedures (Table 1). Antioxidant potentials were found in all assessment techniques (Table 1). The activity revealed high antioxidant ability in terms of radical scavenging activity, with IC50 values of 21.4, 24.2, and 54.3 g/mL for methanolic, aqueous, and ethanolic extracts, respectively. The reducing power of the extracts was revealed to be concentration dependant [27]. The plant displayed antioxidant activity with IC50 values of 5.5 and 4.1 g/mL [25]. The extracts demonstrated immunologic and antioxidant effects on rabbits subjected to a 2 percent H2O2 solution to induce oxidative stress, according to our results [32]. The IC50 value for scavenging activity was determined to be 53 [36]. The plant extract’s naturally occurring antioxidants may be synthesized into nutraceutical that can help prevent oxidative damage in the body.

3.2.2. Anti-Inflammatory

Physical trauma, noxious chemicals, and microbial infections may all produce inflammation, which is the body’s natural reaction to protecting itself from further damage. A host of infections, irritants, and damaged tissues are dealt with during this procedure [1, 6]. Many medications are available to combat inflammation, but long-term usage may result in side effects such as nausea, vomiting, bone marrow depression, and fluid or salt retention [6]. A new supply of structurally essential compounds from plants has been discovered by traditional medicine, which means that it is always expanding its horizons [3]. It is well known that plants are rich in chemical compounds. Compositional diversity in plants has gone largely unexploited, and novel lead chemicals for the treatment and management of inflammation might be found. The crude extract was tested in a variety of solvents and shown to be efficient in treating a variety of inflammation-related diseases, as indicated in Table 1, with a total inhibition of 79.2%. This explains why these species have traditionally been used as polyherbs to treat ulcers [46]. High activity was recorded with the methanolic extract even at 95 compared with the standard at 20.2%, respectively [50]. There is a dose-related impact in all models except for tail-flick, which has no statistically significant activity [52]. In terms of histological changes, the group treated with leaf extract had the highest improvement (ointment), whereas the other group, which had early re-epithelialization, had a greater cellular response to the inflammatory process. Burn wounds are frequent in both rich and developing countries; however, in poor countries, burns represent a serious public health issue due to the high frequency of severe sequelae. Burn wound healing is a complicated process that requires little assistance but still produces discomfort, and the wounds are susceptible to infection and other consequences [152]. Burn healing efficiency of Z. spina extract was assessed in the rat model (Table 1). To sum it up, ointment from the plant leaf was found to have good promise for speeding up the healing of burn wounds (Table 1). In vitro and in vivo studies show that Z. spina may be used to treat and control inflammation.

3.2.3. Antibacterial

Because of their unique qualities, plant extracts have recently got a lot of interest in terms of producing antibacterial agents. Because there is a rising interest in environmental protection, alternative synthesis processes that are ecologically benign and do not require harmful ingredients are needed. Due to activities such as inappropriate and careless administration of medicines in the clinic, bacterial strains have evolved resistant to a broad spectrum of antibiotics, resulting in the creation of multidrug-resistant microorganisms [153]. The preliminary examination of Z. spina against several Gram-positive and Gram-negative bacteria revealed that it was extremely significant. The extract was shown to exhibit action against some of the tested strains at a concentration of 100 mg/mL, with a minimum MIC of 6.25 g/mL for the methanolic extract. These results provide early evidence that crude extracts may be used to treat bacterial infections [56]. Both crystals had antibacterial activity against the tested strains, with SeONPs having greater antimicrobial activity than ZnONPs, according to the findings [24]. The ethanolic extract had the maximum activity against S. aureus, with an activity of 18 mm, while the aqueous extract had the lowest activity against B. subtilis, with an activity of 13 mm [70]. All examined strains were inhibited by the aqueous stem bark extracts, with the maximum inhibition against Klebsiella spp. and E. coli at 20 mm and 20 mm, respectively [76]. Because of the current exploratory findings, Z. spina extract might be a valuable source for the identification and development of novel antibacterial active compounds. The plant may be used to make effective antibiotics against bacterial infections.

3.2.4. Antifungal

Plant extracts and natural goods are gaining popularity since they do not pose a health risk or pollute the environment [111]. The lack of viable treatment choices, as well as pathogen cross-resistance to the earlier medications fluconazole and itraconazole, has required the search for novel antifungal agents from a variety of sources, including medicinal plants [110]. The following study found the extract exhibited the growth of fungal strains (Table 1). Several research projects have highlighted the antifungal properties of the species (Table 1). It was sensitive at 600 mg/mL and was not inhibited at low dosages, showing that the extract possesses antifungal activity [95]. At a concentration of 128 mg/mL, there was no evidence of any action against the Candida species [82]. At a dosage of 100 mg/mL, it showed considerable action with a 20 mm inhibitory zone. These findings might help in the treatment of fungal infections [102]. At a dosage of 500 mg/mL, both ethanolic and aqueous extracts inhibited Candida albicans with inhibition diameters of 32 mm and 18 mm, respectively [94]. As a result, it has been reasonable to conclude that the rise in extract concentration has antifungal action is due to the compounds’ synergistic impact, which increases the contact area and extract access to the fungal strain.

3.2.5. Antidiarrhoeal Effects

Diarrhoea can be described as an adult’s daily bowel movement that surpasses 200 g and contains between 60 and 95% of water. Diarrhoea caused by an infectious agent is the leading cause of newborn mortality in underdeveloped countries [154]. Children under the age of two have been found to have the greatest mortality rates, with a mortality rate of 20 fatalities per 1000 people [154]. Diarrhoea is responsible for more illnesses and deaths in children than any other disease combined in some regions of the world [155]. The World Health Organization has established a Diarrhoeal Disease Control (DDC) program to address the issues of diarrhoea in poor countries. This program involves investigations of traditional medicinal practices [155]. According to the findings, the extract of Z. spina protected rats from castor oil-induced diarrhoea and reduced intraluminal fluid collection and gastrointestinal transit. The LD50 values for intraperitoneal and oral administration in mice were 3465 and 1200 mg/kg, respectively (Table 1). The findings revealed that the extract may include physiologically active components that are antidiarrhoeal, which could explain its traditional use for gastrointestinal disorders.

3.2.6. Antiparasitic

A major public health problem is parasitic infections, which can cause morbidity and even death in their victims. The use of chemical drugs to combat parasites is effective, but there are drawbacks, such as drug resistance, drug residues, and undesirable side effects. Alternative remedies need to be studied [156]. The leaf extract is effective against Egyptian species of schistosomes at concentrations of 6, 25, 12.5, 25, 50, 100, and 200 mg/mL [118]. The extract of the leaves dramatically reduced the viability of leishmanial parasites at , while inducing NO generation and release, apoptosis, and plasma membrane permeability in macrophage cells without causing injury (Table 1). Methanol and aqueous extracts had IC50 values of 60 and 80 g/mL, respectively. The extracts had a devastating effect on the parasites (Table 1). Traditional usage of the leaf extract for antiparasitic ailments may have been based on the discovery of physiologically active components in the leaves.

3.2.7. Antiviral

Since the Stone Age, medicinal plants have played an important role in addressing human health difficulties. They help the human body by acting as restorative, defensive, and supporting agents. Because antiviral medications are frequently ineffective in treating viral infections, there is a growing demand for new antiviral agents that can combat viral resistance. New and better antiviral medicines are needed to combat viral infections. Antiviral medications currently on the market are frequently ineffective in treating viral infections because of the issue of viral resistance [157]. A 50-year-old guy was successfully treated with the leaf extract for rashes (Table 1). When compared with the control group, there was a significant reduction in the growth of the rashes [125]. There is a growing demand for the discovery of novel antiviral substances. Only one research was shown to substantially suppress the development of the virus, according to the study (Table 1). Because of this, the study recommended more research into viral disorders.

3.2.8. Antimalarial

Malaria has long been seen as a public health threat around the globe. More than 3.2 billion individuals are in danger of contacting malaria parasites, according to estimates [3]. The histology investigations of the liver and spleen indicated serious abnormalities. Improved histopathology results were shown in animals that had been treated. Biochemical tests showed a considerable recovery to normal levels of oxidative markers after treatment [126]. Liver function enzymes and histological pictures of the liver were significantly impacted. Because of the significant improvements in hepatic oxidative markers, it has been reasonable to assume that the extracts provide protection against Plasmodium infection [128].

3.2.9. Antidiabetic

Diabetes mellitus is the most common endocrine illness in the world, affecting an estimated 200 million individuals. In 2030, the population is expected to reach 366 million [158]. The highest levels of activity at 25.59 and 39.48%, respectively, at were seen after 7 and 15 days of treatment with 500 mg/kg. At 29.07 and 35.56% after 7 and 15 days, the 500 mg/kg treatment provided the highest hypoglycaemic impact [44]. The extract inhibited alpha-amylase and glucosidase by 54 and 43%, respectively, at doses of 100 g/mL [129]. Diabetic rats exhibited much lower glucose levels and significantly higher blood insulin levels than the control group. The treatment group showed a significant reduction in triglycerides when compared with diabetic control and nondiabetic control rats, showing that it had a hypolipidemic effect (Table 1). The enzyme had high activity against alpha-amylase and glucosidase in methanolic extract, with 8.9 and 39.12 g/mL, respectively [50]. All preliminary research on the plant extract’s ability to inhibit alpha-glucosidase and alpha-amylase showed the species has been shown to be a promising antidiabetic source in both in vitro and in vivo studies (Table 1). Diabetes-related disorders may benefit from the plant extract’s preventive and therapeutic properties. Clinical trials are important because the investigations on this plant were done in vitro and in vivo.

3.2.10. Antiobesity

At pandemic levels, obesity is a key factor in the worldwide burden of chronic disease and disability. There are currently over one billion overweight adults in the globe, with at least 300 million of those individuals being classified as clinically obese [159]. Obesity management and therapy necessitates further research on medicinal plants, given the present conditions. In hypercholesterolemic male rats, the extract improved liver and kidney functions and reduced lipid peroxidation. The antihyperlipidemic actions of this extract may be connected with a suppression of oxidative stress because of its high content of phenolic compounds (Table 1).

3.2.11. Antianxiety

Anxiety is a medical condition that affects both our mental and physical health, and it has a variety of characteristics, including cognitive, emotional, behavioural, and somatic. About one-eighth of the global population is affected by anxiety, making it an essential research topic [160]. A number of studies show Z. spina to have a significant effect on anxiety (Table 1). Compared with the induction group, the data show that the extract considerably suppresses the expression of the markers investigated. The extract may help protect males from the harmful effects of pentylenetetrazole (Table 1). Administering the extract after HgCl2 exposure stopped mercury build-up in the cortical slices. As a result, the levels of malondialdehyde were reduced, as were those of nitrite and nitrate production and nitrite and nitrate creation enzymes. Glutathione levels were also boosted, as were those linked to the antioxidant enzymes glutathione reductase and glutathione peroxidase. Hence, the extract might be used to reduce the damage to neurons caused by HgCl2 poisoning. [133].

3.2.12. Anticancer

Cancer is a disease in which cells divide improperly and uncontrolled. In 2012, around 14 million new cancer cases were reported worldwide, with 8.2 million cancer-related deaths [161]. The development and spread of the contemporary healthcare system has been supported by medicinal plants. As their acceptability and acknowledgment spread over the world, medicinal plants remain the only path ahead. According to the findings of this investigation, the leaf extract contains compounds that have anticancer properties, making it a promising target for future research to create novel anticancer medications (Table 1). If extensive scientific research is conducted, the leaf extract of Z. spina will aid in the development of novel anticancer drugs. There are certain drawbacks to utilizing natural alternatives to pharmaceutical medications. They can be quite poisonous if they are not properly selected and prepared.

3.2.13. Toxicity

The increased interest in using plant extracts to treat human and animal diseases contributes to the current state of knowledge regarding the use of plant products in medicine. There are certain drawbacks to utilizing natural alternatives to pharmaceutical medications. They can be quite poisonous if they are not properly selected and prepared. Because of this, it is essential to determine the plant extracts’ safety. Many studies have proven that medicinal plants contain a wide array of compounds that have a positive biological effect [21, 151]. These components are only beneficial if they are confirmed to be nontoxic or have minimal toxicity. Quite a number of studies have been carried out on the toxicity of Z. spina parts (Table 1) both in vivo and in vitro. In both the short- and long-term experiments, all rats survived at a limit dose of 3000 mg/kg of the root extract. There was no mortality; however, the rats in all groups showed symptoms of tiredness for about 1 to 2 hours (Table 1). Prophage induction did not increase at concentrations of 5, 15, or 30 mg/mL of the leaf extract compared with the control. The pfu/mL did not rise due to the phage’s spontaneous release from lysogenic strains, according to the mutagenic index. As a result, no genotoxic potential was found in the plant extracts tested [64]. The leaf extract was discovered to contain a toxic level of 4050 mg/kg BW. When fed at doses below 1500 mg/kg BW, the leaf extract has no toxic effects on the liver (Table 1). Excessive use of the leaf extract may have toxicological consequences, according to the findings of this study; hence, it is recommended that only modest amounts be used.

3.3. Chemical Composition

Generally, plants have been documented overtime as medicine and/or lead compound sources [162]. Although chemical and synthetic methods have made medicines easier to obtain, the incorporation of plants as sources of medicine or lead compounds in drug discovery has led to the introduction of new and promising lead compounds possessing eccentric biological activities on various diseases [162]. The remarkable biological activity and the traditional medical applications of Z. spina have prompted a lot of investigations into its chemical composition. A total of 431 compounds were reportedly isolated from its genus (Ziziphus) with alkaloids and flavonoids being reported as the major classes of compounds [163]. In Z. spina, saponins, fatty acids, and phenolics in addition to alkaloids and flavonoids have been reported from various parts. This section of this review provides a comprehensive analysis of the phytochemical composition reported from different parts of Z. spina. Different parts of Z. spina have been reported in several studies to contain diverse classes of phytochemicals. The leaves obtained from Indonesia [29, 83] as well as other parts of the world [70, 85], were reported to have shown the presence of flavonoids, alkaloids, saponins, tannins, steroids, and triterpenes. The presence of monosaccharides, reducing sugars, pentose, ketosis, deoxy sugars, and indole alkaloids were reported in the leaves collected from the Plateau state, Nigeria [122, 164]. The detection of glycosides in the aerial parts and cardiac glycoside in the leaves was also reported [85]. Preliminary phytochemical screening of the fruit, pulp, seeds, and almonds of Z. spina collected from Settat and Khouribga cities in Morocco revealed the presence of alkaloids, saponins, triterpenes, quinones, and steroids in the fruit. Alkaloid was reportedly absent in the seed and almonds, while steroid was reportedly absent in the pulp [165]. In contrast to these reports, alkaloids and cardiac glycosides were reportedly absent in the leaves collected from Niger state, Nigeria [93]. Difference in geographical location has been noted to influence the biosynthesis and accumulation of secondary metabolites in plants. In the aerial parts collected in Tabuk, Saudi Arabia [122], and fruits and seeds collected in Qena city, Egypt [75], saponin was reportedly absent. Studies on the bark, fruit, root, seed, and leaf extracts were reported to have shown the presence of steroids, flavonoids, tannins, and alkaloids, but absence of triterpenes [75]. In the same study, phlobatannin was reportedly detected only in the bark extract of the plant. Cyclopeptide alkaloids basically are compounds that are polyamidic in structure with 13-/14- or 15-member ring structure having a side chain that is either basic or neutral in terms of characteristics based on the absence or presence of a terminal nitrogen [163]. These cyclopeptide alkaloids have been reported to be widely distributed in the family Rhamnaceae, particularly the genus Ziziphus [166]. Tuenter et al. [167] reported the isolation of two integerrine-type cyclopeptide alkaloids—nummularine-E and nummularine-D—and three amphibine-B 5(14)-type cyclopeptide alkaloids coupled with β-hydroxy-proline moiety—spinanine-B, spinanine-C, and amphibine-D—from the stem bark of dichloromethane fraction of Z. spina. In another study, a 14-membered cyclopeptide alkaloid, spinanine-A, belonging to amphibian F type was also isolated from the stem bark [168]. From the leaf (80% methanol) extract, the isolation of a new cyclopeptide alkaloid named 4(13) nummularine-C was reported [2]. Many other cyclopeptide alkaloids have been isolated and characterized from different parts of Z. spina, and they are as presented in Table 2 and Figure 3. The high content of saponins in the leaves of Z. spina that has found commercial use in the making of shampoo and detergents [172] has attracted lots of attention to the phytochemistry of this plant. Using 1D, 2D, HRESIMS, and GC-MS (identification of sugar moieties), identification and characterization of dammarane-type saponins, jujuboside B1, 22α-acetoxy christinin A, christinin A1, christinin A2, lotoside III, and 15-acetoxy lotoside IV were reported from n-butanol fraction of the leaves [172]. Ziziphine-F, jubarine-A, and amphibine-H have been reportedly isolated from the stem bark [168]. A novel triterpenic acid, 13-dehydrobetulin, isolated from chloroform fraction, stem ethanolic extract [20], and 3 new dammarane triterpenoids, sidrigenin, konarigenin, and siconigenin, isolated from the leaves [172] have all been reported in Z. spina. Other triterpenic acids that have been reported from Z. spina are summarized in Table 2 and Figure 3. The UHPLC/PDA/ESI-MS analytical technique was used to identify and characterize four new O-flavonoids—myricetin-3-O-(6-rhamnosyl)-hexoside, kaempferol-3-O-(2,6-diharmnosyl)-hexoside, kaempferol-3-O-rhamnoside, and quercetin-3-O-[(2-hexonyl)-6-rhamnosyl]-hexoside—and six new acyl flavonoids—quercetin-3-O-p-coumaroyl (2,6-dirhamnosyl)-hexoside, 6′-caffeoyl 3′,5′-di-C-glucopyranosylphloretin, kaempferol-3-O-(4-O-p-coumaroyl)-2-rhamnosyl-[6-rhamnosyl]-galactoside, quercetin-3-O-(4-O-p-coumaroyl)-2-rhamnosyl-[6-rhamnosyl]-glucoside, kaempferol-3-O-(4-O-p-coumaroyl)-2-rhamnosyl-[6-rhamnosyl]-glucoside, and quercetin 3-O-[4-carboxy-3-hydroxy-3-methylbutanoyl]-(⟶6)-hexoside—isolated from the leaf methanol extract of Ziziphus spina-christi [2]. One new polyphenol, quercetin 3-O-(4-O-trans-p-coumaroyl)-α-L-rhamnopyranosyl-(1⟶2)-[α-L-rhamnopyranosyl-(1⟶6)]-β-D-galactopyranoside, was reportedly isolated from n-butanol fraction of the leaves [172]. LC-MS-ESI analysis of the root ethanol extract revealed the presence of epicatechin [41]. Spectra data from HPLC and UV-visible analysis revealed the presence of catechin, gallic acid, ellagic acid, chlorogenic acid, rutin, isoquercitrin, quercetin, and kaempferol in the methanolic extract of the fruit [31]. Moreover, from the fruit were isolated and characterized different flavonoids carrying different sugar moieties. These flavonoids include quercetin 3-O-robinobioside, quercetin 3-O-β-D-xylosyl-(1⟶2)-α-L-rhamnoside, quercetin 3-O-β-D-xylosyl-(1⟶2)-α-L-rhamnoside-4`-O-α-L-rhamnoside, quercetin 3-O-β-D-galactoside, and quercetin 3-O-β-D-glucoside [173]. A summary of other polyphenolic compounds isolated/detected in Z. spina are presented in Table 2 and Figure 3. Using head space solid-phase microextraction (HS-SPME) and GC-MS methods, identification of α-pinene, β-pinene, β-myrcene, β-phellandrene, L-menthone, carane, trans-caryophyllene, and bicyclogermacrene was achieved as the major constituents of the essential oils of Ziziphus spina-christi [180]. Odeh et al. [181] reported the presence of benzaldehyde, phenylacetyldehyde, phenylethylalcohol, benzene, acetonitrile, 2-ethyl hexanoic acid, octanoic acid, 2-methoxy-4-(1-propanol)-6-acetate phenol, nonanoic acid, decanoic acid, 1-hydroxy-2,4,6-trimethylbenzene, and 5-hydroxymethyl-2-furan carbonyldehyde in honey obtained from Z. spina using HS-SPME-GC-MS methods. In the same study, phenylacetonitrile and 5-hydroxymethyl-2-furan carbonyldehyde were identified as potential markers of honey based on the premise that the different ratios of components present in honey could be utilized as a characteristic to differentiate their floral origins. Said et al. [182] reported the presence of various volatile compounds in the fruits including hexanoic acid, octanoic acid, dodecanoic acid, tetradecanoic acid methyl ester, tetradecanoic acid, hexadecenoic acid methyl ester, oleic acid methyl ester, and oleic acid ethyl ester as the major constituents. GC-MS analysis of stem bark diethyl ether extract after ethyl acetate was reported to have shown the presence of butyl hydroxy toluene bicyclo(4,4,0)dec-2-ene-4-ol, 2-methyl-9-(prop-1-en-3-ol-2-yl), dotriacontane, phytol, and 14-a-H-pregna as the major constituents [66]. Table 2 shows the major constituents of volatile compounds reported from Z. spina. Other compounds such as dodecaacetyl prodelphinidin B3, acetyl betulinic acid, sitosterol-tetraacetyl-β-D-glucoside, pentaacetyl glucose, and octaacetyl sucrose [174] have all been reported from the leaves. NMR (1D and 2D) and GC-MS were used for the identification and characterization of two cyclic amino acids, namely, 4-hydroxymethyl-1-methyl pyrrolidine-2-carboxylic acid and 4-hydroxymethyl-4-hydroxymehtyl-1-methylpyrolidine-2-carboxylic acid, from the seeds of Z. spina. Quantitative phytochemical analysis on different parts of Z. spina has been studied. It is noteworthy that different parts of Z. spina accumulated different constituents with variations in their quantities. Table 3 presents the quantitative phytochemical analysis reported on Z. spina.

4. Conclusion and Future Research

This review attempts to summarize the key findings of numerous research groups involved in the hunt for naturally occurring active principles from Z. spina against a variety of human diseases, the objective of which has been to get new effective medications. In this review, the ethnobotanical, pharmacological, and chemical content of the abundantly diversified species have been emphasized. The study found traditionally the plant parts especially the leaves were used for the treatment of diabetes, malaria, digestive issues, typhoid, liver complaints, weakness, skin infections, urinary disorders, obesity, diarrhoea, and sleeplessness. Preclinical investigations have already been conducted on a variety of biological activities. The leaves were found to have significant biological activity, and this is due to the presence of high contents of polyphenol compounds. There is a lot of room for fresh scientific and developmental research. The evidence reported in this analysis provides a foundation for future investigations that are desperately required. Detailed examinations of the following topics are among the top objectives for future research: (1) identification of species based on micromorphology and anatomy in each region of the world, (2) mechanism of action of the isolated compounds, (3) clinical trial, (4) the standard dose and safety of the leaf be established, and (5) formulation of herbal medicine from the leaf.

Data Availability

The data are available within the manuscript.

Conflicts of Interest

The authors do not have any potential conflicts of interest to declare.

Authors’ Contributions

All the authors contributed equally to data search, analysis of the retrieved data, and drafting the manuscript.