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, (1)H NMR, (13)C 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 μg/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.