Abstract
Background. The plant kingdom is rich with a numerous number of plants with various medical properties which can be used to treat various medical issues. Sri Lanka is a country full of biodiversity which is gifted with many plant resources. It has a rich history of traditional medicine systems consisting of Ayurveda, Unani, and Deshiya Chikitsa, where these plant resources are used as remedies for the diseases. In the traditional medicine system, various plant parts such as leaves, roots, fruits, flowers, and bark are used to treat disease conditions. Although less attention is paid to the medicinal importance of the flowers, some of them have been used to treat many diseases from the ancient time. Some properties of the flowers may differ from the properties of the other plant parts. For example, Sesbania grandiflora (Katuru murunga) flowers have shown anticancer properties against various cell models whereas some flowers have shown antispermatogenic properties. Flowers of Woodfordia floribunda (Militta) are added as fermenting agents in the preparation of Arishtas in Ayurveda. Also the most popular Clove oil is obtained from the flower buds of Syzygium aromaticum (Karabu-neti) which is used to treat toothaches since it has antibiotic and antiseptic properties. This article gives an overview of herbal flowers used in the traditional medicine system of Sri Lanka and their pharmacological importance. Method. A comprehensive literature survey was done on the medicinally important flowers in Sri Lanka. Data was collected from Libraries of Ayurveda in Sri Lanka and from scientific databases. Results. According to the survey many flowers are used as astringent, cardiac tonic, and febrifuge. Also some flowers are used to treat dysentery, diarrhoea, and indigestion. Some flowers are useful in the treatment of bleeding piles while some are useful in the treatment of asthma and bronchitis. Conclusion. It was revealed that there are many flowers with valuable therapeutic effects. Traditional medicine systems prevailing in Sri Lanka have made use of these flowers with therapeutic effects to cure so many diseases. The review of medicinally important herbal flowers provides knowledge and pharmacological leads which will help for the wellbeing of the human beings. Although there are phytochemical studies done to identify the chemical compounds on some flowers, chemical composition of many flowers remains unrevealed. So further studies need to be done to identify the chemical composition of these flowers.
1. Introduction
Plants have been used by human beings to cure diseases from ancient time. Therefore herbal drugs play a major role in traditional medicine. According to the World Health Organization (WHO), herbal drugs are the best source to obtain a variety of drugs. In developing countries, about 80% of the population depends on traditional medicine [1]. The traditional medicine which is mainly based on plant sources consists of significant amounts of bioactive compounds. These compounds provide valuable health effects. Since modern medicine claimed to possess irreversible adverse events, herbal plants play a major role in delivering therapeutic effects with less adverse events to human beings [2].
Sri Lanka is a country full of biodiversity which is gifted with many plant resources. It has been reported that there are 3771 flowering plant species grown in Sri Lanka. Out of them about 927 (24%) are endemic to the country. Also, 1430 species are considered to have medicinal value. Out of these medicinal plants, 174 (12%) are endemic to Sri Lanka. Also, it is reported that around 250 species are commonly used in traditional medicine. Since there are a huge number of medicinal plants in Sri Lanka, it has a rich history of traditional medicine systems [72]. The main traditional medicine systems that prevail in Sri Lanka are Ayurveda, Siddha, Unani, and Deshiya Chikitsa. In Ayurveda, herbal preparations are used mostly to cure diseases while in Siddha mineral preparations are used mostly. Deshiya Chikitsa also uses herbal preparations. The Unani differs from these concepts. Ayurveda system of Sri Lanka nearly uses 2000 herbs [73]. These systems fulfill 60-70% of the rural populations’ primary health care needs. The knowledge regarding the use of these herbal plants has been passed from generation to generation in the traditional medicine systems. So there are numerous plants with valuable health benefits used in these traditional formulations where the knowledge regarding the therapeutic use is depleting day by day [72].
In the recent past, there has been a tremendous increase in the research done on herbal medicine and there has been an increase in the use of herbal products in the developing countries and in developed countries. Today nearly 51% of the approved drugs are directly or indirectly derived from the herbal plants [74]. Plants provide the constituents for the synthesis of new drugs and chemical compounds. The secondary metabolites, such as tannins, terpenoids, alkaloids, flavonoids, phenols, steroids, glycosides, volatile oils, etc., also are a major source of therapeutically valuable compounds [75]. These compounds of pharmacological importance can be obtained from various plant parts such as leaves, roots, flowers, bark, etc. [76]. Flowers are reproductive parts of a plant which are also used for nutritive and medicinal properties. Flowers are used either directly or as a decoction, tincture, or mixed with other ingredients to treat diseases [77]. Flowers such as Stereospermum suaveolens (Roxb.)/Bignonia suaveolens Roxb (Palol) are used to treat malaria and bronchitis [61]. Some flowers such as Woodfordia floribunda (Militta) are added as fermenting agents in the preparation of Arishtas in Ayurveda [3]. Also some flowers possess properties that are different from the pharmacological properties of the other parts of the plant. For example, flowers of Butea monosperma have diuretic, astringent, and tonic properties while the root of this plant has analgesic properties [18].
According to the literature survey there were numerous review articles about medicinal plants. But only few research papers were focused on the particular parts of the medicinal plants. Therefore the study of pharmacological importance of the flowers is benefitted in the development of novel drugs.
2. Methodology
A comprehensive literature survey was done on the medicinally important herbal flowers in Sri Lanka. The data was obtained from the Libraries of Navinna Ayurveda Hospital, Maharagama, Sri Lanka, and Institute of Indigenous Medicine, University of Colombo, Rajagiriya, Sri Lanka. Books like Medicinal Herbs and Flowers [78], The Chemistry and Pharmacology of Ceylon and Indian Medicinal Plants [3], Medicinal Plants Used in Ceylon-Part I [7], Part II [25], Part III [24], Part IV [27], and Part V [51], Sri Lankawe Osu Shaka Saha Ewaye Wadagathkama [8], and Medicinal Herbal [5] were used. Further research was carried out based on the scientific names collected from the flowering ayurvedic plants from these books using scientific databases PubMed, Google Scholar, and Web of Science. Nine Ayurveda books and 69 journal articles were referred in this article.
3. Results and Discussion
Table 1 includes the information collected from the extensive literature survey and Figure 1 includes some of the chemical structures of the phytochemicals found in Sri Lankan herbal flowers.
(a) Vasicine
(b) Cynidin-3-glucoside
(c) Malvidin-3-glucoside
(d) Peonidin-3-glucoside
(e) α-inone
(f) β- ionone
(g) Kaempferol-3-galactoside
(h) 7-epi-eudesm-4(15),11(13)-diene-1β,3β-diol
(i) 7-epi-1β-hydroxy-β-eudesmol
(j) α-copaene
In this review an attempt has been taken to present the medicinally important flowers in Sri Lanka and their therapeutic uses. Generally, flowers have similar pharmacological properties as their other parts. But several flowers were reported to have special medicinal uses. Flowers such as Stereospermum suaveolens (Roxb.)/Bignonia suaveolens Roxb (Palol) flowers are used to treat malaria and bronchitis. Also the most popular Clove oil is obtained from the flower buds of Syzygium aromaticum (Karabu-neti) which is used to treat toothaches since it has antibiotic and antiseptic properties. Some flowers such as Woodfordia floribunda (Militta) are added as fermenting agents in the preparation of Arishtas in Ayurveda. Also powder of this flower is administered with honey in the treatment of leucorrhoea and water decoction of the fresh flowers of this plant either alone or in combination with ginger (Zingiber officinale) is used for the treatment of dysentery. Flowers of Wrightia antidysenterica Linn (Sudu idda/Wal-idda) are important for the treatment of Russell’s viper snake bite and to treat Gonorrhea. The leaf, flower, and seeds of Sphaeranthus hirtus/indicus (Mudamahana) plant are ground into a paste and applied topically to treat skin diseases. Juice of Saraca indica (Asoka) flowers are used as a cardiac tonic. Also some flowers possess properties that are different from the pharmacological properties of the other parts of the plant. For example Butea monosperma flowers have diuretic, astringent, and tonic properties while the root of this plant has analgesic properties. The flowers of Punica granatum had been used in traditional medicine to treat vaginal discharge and diarrhoea while the juice of fruit is used to treat gallbladder diseases.
4. Conclusion
An extensive literature survey done on the flowers with medicinal importance in Sri Lanka revealed that there are many flowers with valuable therapeutic effects. Some plants are endemic to Sri Lanka while some are distributed throughout the world. Traditional medicine systems prevailing in Sri Lanka have made use of these flowers with therapeutic effects to cure so many diseases. Considering these facts need was felt to collect details regarding the chemical composition and their ailments. Although there are number of phytochemical studies were carried out using these flowers, exact chemical composition is remain unrevealed. Hence, further studies are warrants on these flowers in order to identify their biological activities, mechanisms of action, and the chemical composition. Further, there is a possibility of developing novel formulations for various diseases for the betterment of the mankind. Thus the review of the medicinally important flowers in Sri Lanka provides details regarding the pharmacological leads for the wellbeing of the human society.
Conflicts of Interest
There are no conflicts of interest regarding the publication of this paper.