Abstract

• Stephania venosa (Bl.) Spreng (Taung-kya), belonging to the family Menispermaceae and is a rich source of alkaloids commonly found as herbaceous perennial vine with a large tuber. The aim of the research includes preliminary phytochemical investigations, isolation and identification of bioactive chemical constituent and in vitro antimicrobial and antioxidant activities of different crude extracts from the tuber of S. venosa. The preliminary phytochemical screening revealed the presence of alkaloids, α-amino acid, carbohydrates, glycosides, flavonoids, organic acids, phenolic compounds, reducing sugars, steroids, saponins and tannins in the samples by using the standard methods. The air-dried powder plant sample was subjected to cold percolation with 80 % methanol and fractionation with petroleum ether only, petroleum ether and ethyl acetate, ethyl acetate only, and ethyl acetate and methanol. The isolated compound (0.03 g, 0.06%) was separated from ethyl acetate fraction by using silica gel column chromatographic separation method. It was identified by using modern spectroscopic methods such as UV-visible, FT IR, 1H NMR, 13C NMR and mass spectrometry and also by comparing with the reported data. The antimicrobial activity of different crude extracts (PE, EtOAc, EtOH, MeOH and Watery) from tuber of S. venosa was tested by the agar well diffusion method. Ethyl acetate extract has the most potent antimicrobial activity (the inhibition zone diameter range between 17 to 22 mm) against tested microorganisms except as Bacillus pumilus. The antioxidant activity was investigated by using DPPH free radical scavenging assay method. The IC50 values of watery and ethanol extracts were found to be 173.61 and 134.93 μg/mL, respectively. The IC50 value of isolated compound was also observed as 24.43 μg/mL. Therefore, the isolated compound possesses higher potent antioxidant activity than the extracts.