Microbial transformations of (±)-7-O-prenylnaringenin (7-PN, 1) and (±)-7-O-allylnaringenin (7-AN, 2) have isolated four metabolites (3-6). Structures of these novel compounds were identified as 5,4'-dihydroxy-7-O-[(2E)-4-hydroxy-3-methyl-2-buten-1-yl]flavanone (3), 5,4'-dihydroxy-7-O-(2,3-dihdroxy-3-methylbutyl)flavanone (4), 5,4'-dihydroxy-7-O-(2,3-dihdroxypropyl)flavanone (5), and 5-O-β-D-glucopyranosyl-7-O-allyl-4'-hydroxyflavanone (6) based on spectroscopy. Compounds 1-6 were evaluated for their radical scavenging capacity using DPPH (2,2-diphenyl-1-picrylhydrazyl). The derivatives 3-6 exhibited more potent antioxidant activity than their corresponding substrates 1 and 2.
Keywords: 7-O-allylnaringenin; 7-O-prenylnaringenin; DPPH; Microbial transformation.