Microbial Metabolism Part 9.1) Structure and Antioxidant Significance of the Metabolites of 5,7-Dihydroxyflavone (Chrysin), and 5- and 6-Hydroxyflavones

5,7-Dihydroxyflavone (chrysin) (1) when fermented with fungal cultures, Aspergillus alliaceous (ATCC 10060), Beauveria bassiana (ATCC 13144) and Absidia glauco (ATCC 22752) gave mainly 4'-hydroxychrysin (4), chrysin 7-O-β-D-4-O-methylglucopyranoside (5) and chrysin 7-sulfate (6), respectively. Mucore ramannianus (ATCC 9628), however, transformed chrysin into six metabolites：4'-hydroxy-3'-methoxychrysin (chrysoeriol) (7), 4'-hydroxychrysin (apigenin) (4) 3',4'-dihydroxychrysin (luteolin) (8), 3'-methoxychrysin 4'-O-α-D-6-deoxyallopyranoside (9), chrysin 4'-O-α-D-6-deoxyallopyranoside (10), and luteolin 3'-sulfate (11). Cultures of A. alliaceous (ATCC 10060) and B. bassiana (ATCC 13144) metabolized 5-hydroxyflavone (2) into 5,4'-dihydroxy-flavone (12) and 4'-hydroxyflavone 5-O-β-D-4-O-methylglucopyranoside (13), respectively. 6-Hydroxyflavone (3) was transformed into 6-hydroxyflavanone (14), flavone 3-O-β-D-4-O-methylglucopyranoside (15) and (±)-flavanone 6-O-β-D-4-O-methylglucopyranoside (16) by cultures of Beauveria bassiana (ATCC 13144). The struc-tures of the metabolic products were elucidated by means of spectroscopic data. The significance of the metabo-lites as antioxidants in relation to their structure is briefly discussed.