Bioassay-Guided Isolation and Antioxidant Evaluation of Flavonoid Compound from Aerial Parts of Lippia nodiflora L.

The present study was designed to identify the DPPH (2, 2-diphenyl-1-picrylhydrazyl) free-radical scavenging constituents from methanol extract of L. nodiflora using bioassay-guided fractionation. The ethyl acetate fraction (EAF) revealed a strong antioxidant activity, compared to other fractions through in vitro DPPH radical-scavenging assay. The repeated fractionation of active EAF by silica gel column chromatography yielded a compound with strong antioxidant potential. The isolated bioactive compound was determined as 2-(3, 4-dimethoxyphenyl)-5-hydroxy-7-methoxy-4H-chromen-4-one (5-hydroxy-3', 4', 7-trimethoxyflavone), by comparing spectral data (UV, IR, H-1 NMR, C-13 NMR, and MS) with literature reports. The isolated compound demonstrated an excellent antioxidant activity through all antioxidant assays and also significantly inhibited lipid peroxidation at a concentration of 50 mu g/mL. The results obtained suggested that extracts from L. nodiflora or its derived phytocompound can be used potentially as a bioactive source of natural antioxidants by contributing beneficial health effects.