Effects of Extraction Solvents on Phytochemical Screening, Cytotoxicity and Anti-Obesity Activities of Selected Sri Lankan Medicinal Plants

Background: Phytoconstituents are known to have an arena of health benefits. The choice of extraction solvents for a desired pharmacological activity is poorly characterized. Objectives: The present study compared the use of different solvents to extract phytoconstituents, evaluate cytotoxicity and anti-obesity activities. Materials and Methods: Leaves, bark, flowers or tubers of fourteen commonly utilized plants in the Sri Lankan Ayurvedic system were used to prepare extracts of distilled water (DW), ethanol or n-hexane. Phytochemical screening, total phenolic and flavonoid contents (TPC and TFC), cytotoxicity and triglyceride assays were performed. Results: DW served as the best solvent to extract the highest yield of phytochemicals followed by ethanol marking hexane as the least efficient solvent. The water extract (WE) of Averrhoa bilimbi leaves and ethanol extract (EE) of Cassia auriculata showed the highest TPC. The TFC was lowest in the hexane extract (HE) of all plants. The WE of plants showed ≥75% cell viability below 500 μg/mL with no potential anti-adipogenic activity. The EE of Justicia adhathoda showed maximum lipid inhibition (88.31%), followed by Aerva lanata (74.65%), and Cyperus rotundus (74.04%) at 100 μg/mL. The EE of Ipomoea aquatica (45.11%), Murrya koenigii (41.04%), and Hemidesmus indicus (32.97%) showed the highest viable anti-adiposity activity at 50 μg/mL. Conclusion: The WE of most plants provided a greater yield of phytoconstituents enabling their safe usage in higher doses during Ayurvedic medication. Ethanol served as a better solvent to extract constituents responsible for anti-adipogenesis and no possible correlation was found between the phenolic content and anti-adiposity.