Saponin, Polyphenol, Flavonoid content and α-glucosidase Inhibitory Activity, Antioxidant Potential of Launaea sarmentosa Leaves grown in Ben Tre province, Vietnam

Launaea sarmentosa (Willd) Schultz-Bip.ex Kuntze, a creeping herb, belongs to family Asteraceae. It is distributed in sandy coasts of India, Sri Lanka, Malaysia, East Africa and Vietnam. In Vietnamese folk medicine, whole plant possess tonic, soporific, diuretic, laxative properties and the roots are used to benefit milk for mothers after childbirth, instead of Lactuca indica. Up to now, the phytochemicals and bioactivities of this plant are not yet been examined. The present study was designed to investigate the saponin, polyphenol and flavonoid contents as well as α-glucosidase inhibitory and antioxidant activities of the leaves of L. sarmentosa. Preliminary phytochemical screening of this plant were found to give positive reactions for flavonoid, saponin, alkaloid, tannin, and steroid compounds. The result of quantitative determination showed that the leaves contains high amount of polyphenol compounds (290.90 mg GAEs/g extract), lower amount of flavonoids (85.47 mg QEs/g extract) and the saponin content was found to be 10.8 % (per dry weight). As expected, the ethanol extract had a antioxidant potential with IC₅₀ value of 24.15 μg/mL in DPPH experiment, compared to that of vitamin C. Meanwhile, the α-glucosidase inhibitory assay showed inhibited enzyme activity with IC₅₀ value of 67.09 μg/ml.