Isolation of free radical scavenging antioxidant from water spinach (Ipomoea aquatic Forsk)

Ipomoea aquatica Forsk, a green leafy vegetable that is a rich source of vitamins and amino acids with many health benefits, has been explored for the isolation and identification of its bioactive compounds. Activity-guided repeated fractionation of a methanol extract on a silica gel column followed by an XAD column yielded a compound that exhibited antioxidant activity with an EC50 value of 83 ± 1.02 µg ml−1 reaction mixture. It also showed very strong lipid peroxidation-inhibitory activity in a liposome model system with an EC50 value of 72.2 ± 0.9 µg ml−1. However, it showed negligible metal-chelating activity. Based on UV, 2D nuclear magnetic resonance and gas chromatography/mass spectrometry studies, the compound was tentatively identified to be 7-O-β-D-glucopyranosyl-dihydroquercetin-3-O-α-D-glucopyranoside. This is the first report on the antioxidant properties of I aquatica leaf extracts. Copyright © 2005 Society of Chemical Industry