Biological Studies of Some Selected Medicinal Plants from Kathmandu Valley and Isolation of Chemical Compounds

Abstract

The aim of this study is to investigate the phytochemical and biological properties of some selected medicinal plants from Kathmandu valley and isolation of phytoconstituents from active plant extract. The methanolic extracts of Ageratina Adenophora, Cupressus sempervirens and Lantana camara aerial parts were analyzed for their phytochemical analysis, toxicity test, antioxidant activity, total phenolic and total flavonoid content, antidiabetic properties and isolation of chemical constituents from active plant fraction and FTIR analysis. The toxicity test was studied by brine shrimp lethality test. The antioxidant potential was evaluated by DPPH radical scavenging assay. The amount of total phenolic and flavonoid was estimated with the Folin-Ciocalteu reagent and aluminium chloride method, respectively. The α amylase enzyme inhibition activity was performed to evaluate the inhibition percentage for each extract. The phytochemical analysis showed the presence of various secondary metabolites like alkaloids, flavonoids, carotenoids, coumarins, glycosides, polyphenol, carbohydrate, saponin, tannins, terpenoids, quinones, and volatile oil & fats. The methanolic extracts of Ageratina adenophora was found to be cytotoxic against brine shrimp as shown by its LC50 value of 833.68 µg/mL. The methanolic extracts of Lantana camara (106.179 ± 11.390 µg/mL) showed the strongest DPPH radical scavenging activity as its IC50 values were close to standard ascorbic acid (17.456 ± 0.822 µg/mL). Lantana camara showed the highest phenolic (10.2 ± 0.343 mg GAE/g) and flavonoid content (1.872 ± 0.16 mg QE/g) respectively. In addition, Ageratina adenophora methanolic extracts were found to inhibit enzymatic activity of α-amylase under in-vitro starch digestion bioassay with the IC50 value of 1.843 ± 0.007 mg/mL. The FTIR measurement revealed the presence of C=O, O-H and C-H stretching bands at the functional group region. Keywords: Phytochemical, antioxidant, phenolic, flavonoid, antidiabetic, αamylase.