Flavonoids and Antioxidant Effects of Piper sarmentosum

Piper sarmentosum has long been a precious herb, used as a remedy for diseases such as gout, joint pain, etc. The chemical compositions mainly contain alkaloids, flavonoids, saponins, terpenoids, and phenols. However, up to date, there have been few studies on the chemical compositions and antioxidant activity in Vietnam. The experiments indicated that the ethyl acetate fraction had the highest content of polyphenols (254.1 mg GAE.g -1) and total flavonoids (132.2 mg QE.g -1), as well as strong antioxidant activity in DPPH and ABTS assays. From the ethyl acetate fractions, by chromatographic techniques, two substances named afzelin ( 1 ) and kaempferol ( 2 ) were isolated. Compound 2 exhibited strong antioxidant activity with IC 50 values of 6.37 and 4.93 μg/mL in the DPPH and ABTS models, respectively, while compound 1 had moderate activity.