International Journal of Drug Development and Research

INTRODUCTION

Plants have an almost limitless ability to synthesize aromatic substances mainly secondary metabolites, of which at least 12,000 have been isolated, a number estimated to be less than 10% of the total. In many cases, these substances serve as the molecules of plant defence against predation by microorganisms, insects, and herbivores. Further, some of which may involve in plant odour (terpenoids), pigmentation (tannins and quinines), and flavour (capsaicin). However, several of these molecules possess medicinal properties1.

Plants are endowed with free radical scavenging molecules, such as vitamins, terpenoids, phenolic acids, lignins, stilbenes, tannins, flavonoids, quinones, coumarins, alkaloids, amines, betalains, and other metabolites, which are rich in antioxidant activity. Studies have shown that many of these antioxidant compounds possess anti-inflammatory, anti-atherosclerotic, antitumor, anti-mutagenic, anticarcinogenic, antibacterial, and antiviral activities. The ingestion of natural antioxidants has been associated with reduced risks of cancer, cardiovascular disease, diabetes, and other diseases associated with ageing, and in recent years, there has been a worldwide trend towards the use of the natural phytochemical present in berry crops, teas, herbs, oilseeds, beans, fruits and vegetables2.

Pavonia zeylanica is a plant that has shown potential as a source of chemotherapeutic compounds. Phytochemical studies have revealed that the plant is rich in flavonoids and other water soluble polyphenolic compounds. This present study, therefore investigated the physicochemical and phytochemical compositions of this plant.

MATERIALS AND METHODS

Plant Material

A survey was conducted during 2007 to 2008 in Nanjangud area of Karnataka to collect the plant material of Pavonia zeylanica. Botanical species were collected from the forests of Nanjangud area, Mysore district, Karnataka, voucher specimens were collected, identified properly consulting a flora and the same has been deposited in the Department of Botany, University of Mysore, Mysore-06.

Leaves were shade dried and powdered to 40-mesh size. The physicochemical parameters like extractive values, florescence characteristics of powdered leaf and leaf extract, preliminary phyto-profiling and phytochemical analysis, were determined as per WHO guidelines1. The average percentage w/w of the ash content and the extractive values were determined. The Fluorescence analysis was carried out according to the reported method3,4 wherein the colour of the powdered leaf and leaf extract were also studied under ordinary and ultra-violet light at 366nm. Powdered leaf material was successively extracted with Petroleum ether, Benzene, Chloroform, Acetone, methanol, ethanol and water in soxhlet apparatus and was subjected for identification of various plant constituents5,6.

Extraction of plant leaf material

The powdered plant leaf material was subjected to successive solvent extraction taking from polar to non-polar solvents like water, ethanol, methanol, acetone, chloroform, benzene and petroleum ether. 20gms of powdered plant material was subjected to soxhlet extraction for 8 hrs with 250ml of the various solvents. The extracts obtained were later kept for evaporation to remove the excessive solvents. These extracts were stored in a cool dry place for the analysis for the presence of preliminary phytochemicals.

Analysis of primary and secondary metabolites in the extracts of Pavonia zeylanica

The primary metabolites like; proteins, carbohydrates and fixed oils and fats, were analyzed for their presence as per the standard procedures7, 8. Similarly, the secondary metabolites like, alkaloids, flavonoids, saponins, phenolics, tannins volatile oils, terpenoids and glycosides were also assessed in the leaf extracts of Pavonia zeylanica. All the data generated from the study were subjected to arithmetic mean with standard deviation for statistical analysis.

RESULTS AND DISCUSSIONS

The extracts of P.zeylanica was also analyzed for Physicochemical values which were determined and the observed results were tabulated and statistically analyzed (Table No. 1,2,3,4,5 & 6). The determination of ash value for percentage of total ash, acid insoluble ash, sulphated ash and water soluble ash were 5.66, 0.64, 6.99 and 1.09 %w/w of leaves respectively. Extractive values of water soluble and alcohol soluble were observed to be 11.21 and 22.51 %w/w of leaves respectively (Table.1).

The parameters for the analysis of leaf of P.zeylanica were also carried out wherein the hemolytic activity for methanolic extract showed less than 100mg/ml of activity whereas water extract showed 8.05mg/ml of activity. The foaming index was found to be less than 100. The total tannin content was 1%. The total bacterial and fungal count was 7×103 and 6×104 respectively. E.coli was present showing 5×103 whereas Salmonella typhii was absent (Table 2).

The fluorescence characteristics for the leaf powder with different acids and bases varied from a range of yellow to dark green under the ordinary light whereas for UV light it ranged from yellowish brown to brownish red. The leaf extract also showed a varied range of colors from pale green to greenish brown whereas under UV light it ranged from greenish brown to brownish red (Table 3& 4).

The preliminary phyto–profiling for the leaves extracts of P.zeylanica was carried out wherein the consistency was found to be sticky in the non polar to not so polar solvent extracts whereas the polar solvent extracts were found to be non-sticky (Table 5). The percentage yield w/w of the extracts was analyzed wherein the highest yield was found to be in the ethanolic extract.

P.zeylanica when subjected to phytochemical analysis showed the presence of proteins in ethanolic extract alone and carbohydrates in all the extract. Proteins were present only in ethanolic extract and carbohydrates were present in all the extract. Flavonoids and phenols were present only in ethanolic extract. Alkaloids and terpenoids were present in ethanolic and aqueous extract. Steroids and saponins were absent in all the extracts. Tannins were absent in ethanolic and chloroform extracts (Table 6).

The presence of phyto-chemicals in P.zeylanica extract revealed that, tannins are known to be useful in the treatment of inflamed or ulcerated tissues and they have remarkable activity in cancer prevention and anticancer; similar reports were also made by previous Researchers11. Flavonoids have been shown to exhibit their actions through effects on membrane permeability, and by inhibition of membrane-bound enzymes such as the ATPase and phospholipase A2. Flavonoids serve as health promoting compound as a results of its anion radicals12. These observations support the usefulness of this plant in folklore remedies in the treatment of stress-related ailments and as dressings for wounds normally encountered in circumcision rites, bruises, cuts and sores13.

Saponins, which are present in plants, have been suggested as possible anti-carcinogens. They possess surface-active characteristics that are due to the amphiphilic nature of their chemical structure. The proposed mechanisms of anti-carcinogenic properties of saponins include direct cytotoxicity, immuno-modulatory effects, bile acid binding and normalization of carcinogen-induced cell proliferation. However, the anti-carcinogenic effects of saponins from commonly consumed plant foods have not been studied. Soybeans are one of the most important sources of dietary saponins. They are the main protein supplier in many vegetarian diets14.

The plant extract was also positive for steroids which are very important compounds especially due to their relationship with compounds such as sex hormone15. The presence of these phenolic compounds in this plant contributed to their anti-oxidative properties and thus the usefulness of these plants in herbal medicament. Phenols have been found to be useful in the preparation of some antimicrobial compounds such as dettol and cresol. This plant is used routinely among many tribes in Africa for the treatment of various diseases. for centuries and one of their common biological properties is their cytotoxicity 16, and their absence in this plant tend to lower the risk of poisoning by the plant. Banerjee (2009) in his present investigation has stated the importance of standardization of parameters of Bridelia retusa bark, qualitative and quantitative microscopic characters, ash values, extractive values, and phytochemical profiles of petroleum ether, chloroform, ethyl acetate, methanol and aqueous extracts of the plant. These standardized parameters would be of immense help in authenticating Bridelia retusa17.

Thus, P.zeylanica containing these compounds may serve as a potential source of bioactive compounds in the treatment of cancer.

Conclusions

New anticancer drugs derived from research on plant will be continuously discovered. The activities of phytochemicals and the synergistic action shown by them make them ideal in alternative cancer therapies. The chemopreventive effects that most phytochemicals exert are likely to be the sum of their effect on several distinct mechanisms working inside the cell. The phytochemicals have been focused for the research since 1930’s but many of them have been used in traditional medicines for thousands of years. Proper identification of drugs and their evaluation on a scientific basis is therefore of prime significance. This can certainly help to rejuvenate the ancient system of medicine like ayurveda.

Tables at a glance

Table 1 Table 2 Table 3 Table 4 Table 5 Table 6

References

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