Eleven Microbial Metabolites of 6-Hydroxyflavanone

6-Hydroxyflavanone (1) when fermented with fungal culture Cunninghamella blakesleeana (ATCC 8688a) yielded flavanone 6-O-β-D-glucopyranoside (2), flavanone 6-sulfate (3), and 6-hydroxyflavanone 7-sulfate (4). Aspergillus alliaceus (ATCC 10060) also transformed 1 to metabolite 3 as well as 4'-hydroxyflavanone 6-sulfate (5) and 6,4'-dihydroxyflavanone (6). Beauveria bassiana (ATCC 7159) metabolized 1 to 6 and flavanone 6-O-β-D-4-O-methyglucopyranoside (7). Mucor ramannianus (ATCC 9628) transformed 1 to 2,4-cis-6-hydroxyflavan-4-ol (8), 2,4-trans-6-hydroxyflavan-4-ol (9), 2,4-trans-6,4'-dihydroxyflavan-4-ol 5-sulfate (10), 1,3-cis-1-methoxy-1-(2,5-dihydroxyphenyl)-3-phenylpropane (11) and 2,4-trans-flavan-4-ol 6-sulfate (12). Structures of the metabolic products were elucidated by means of spectroscopic data. None of the metabolites tested showed antibacterial, antifungal and antimalarial activities against selected organisms. However, weak antileishmanial activity was observed for metabolite 11 when tested against Leishmania donovani.