Antioxidant activity of the fractions from water lettuce (Pistia stratiotes) extract

Abstract

Free radicals including reactive oxygen species are continuously increasing in the human body. This condition causes the unbalance between free radicals and antioxidants in the human body. An antioxidant is a compound with the ability to reduce the harmfulness of the free radical. This study aimed to determine the antioxidant activity of fractions and analyzed the functional groups of water lettuce (Pistia stratiotes) methanol extract. The separation process was performed by using thin-layer chromatography (TLC) and column chromatography. The separated fractions were measured for their antioxidant activity by using the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) assay. The functional groups of each fraction were determined by using Fourier-transform infrared (FT-IR) spectroscopy. The separation of water lettuce extract by using column chromatography produced seven fractions with different colors and confirmed by using TLC. The antioxidant activity showed the highest activity in the third fraction with a half-maximal inhibitory concentration (IC50) value of 131.66 ppm. The fifth fraction with the IC50 was about 184.62 ppm. Whereas, the first, second, fourth, sixth, and seventh fractions were relatively weak with the IC50 more than 200 ppm. The FT-IR spectrum also showed that the intensity hydroxyl group in the third fraction higher than the seventh fraction.