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Title: Bioconversion of 7-hydroxyflavanone: isolation, characterization and bioactivity evaluation of twenty-one phase I and phase II microbial metaboites

Author
item MIKELL, JULIE - University Of Mississippi
item KHAN, IKHLAS - University Of Mississippi

Submitted to: Chemical and Pharmaceutical Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2012
Publication Date: 9/2/2012
Citation: Mikell, J.R., Khan, I.A. 2012. Bioconversion of 7-hydroxyflavanone: isolation, characterization and bioactivity evaluation of twenty-one phase I and phase II microbial metaboites. Chemical and Pharmaceutical Bulletin. 60(9):1139-1145.

Interpretive Summary: Flavonoids, including 7-hydroxyflavanone are important phytochemicals found in fruits, vegetables and beverages. They are also in many dietary supplements and have been described as health-promoting and disease-preventing. However, flavonoids are known to interact with cytochromes P450 drug-metabolizing enzymes by inducing biosynthesis of CYP’s, modulating their activity (inhibition or stimulation) and bringing about transformation of flavonoids to metabolites, which in turn interact with CYP’s and modify their activities. From studies conducted over the last decade the bioactive forms of flavonoids may not necessarily be the naturally occurring forms, such as the aglycone or their glycosidic forms but instead their conjugates and metabolites. Microorganisms are good predictors of mammalian drug metabolites with the ability to yield sufficient quantities of metabolites for structure analysis and further pharmacological evaluation. In this study, microbial metabolism of 7-hydroxyflavanone resulted in the formation of twenty-one metabolites from 7 fungal cultures, Cunninghamella blakesleeana,Mortierella zonata, Beauveria bassiana, Chaetomium chocloides, Mucor ramannianus, Aspergilus allaiceus, and Rhizopus oryzae. The structures of the metabolites were determined by spectroscopic data. None of the metabolites showed antibacterial, antifungal and antimalarial activities against selected organisms. Metabolites 4 and 16 showed weak antileishmanial activity.

Technical Abstract: Microbial metabolism of 7-hydroxyflavanone (1) with fungal culture Cunninghamella blakesleeana (ATCC 8688a), yielded flavanone 7-sulfate (2), 7,4’-dihydroxyflavanone (3), 6,7-dihydroxyflavanone (4), 6-hydroxyflavanone 7-sulfate (5), and 7-hydroxyflavanone 6-sulfate (6). Mortierella zonata (ATCC 13309) also transformed 1 to metabolites 2 and 3 as well as 4’-hydroxyflavanone 7-sulfate (7), flavan-4-cis-ol 7-sulfate (8), 2’,4’-dihydroxychalcone (9), 7,8-dihydroxyflavanone (10), 8-hydroxyflavanone 7-sulfate (11), and 8-methoxy-7-hydroxyflavanone (12). Beauveria bassiana (ATCC 7159)metabolized 1 to 2, 3, and 8, flavanone 7-O-ß-D-O-4-methoxyglucopyranoside (13), and 8-hydroxyflavanone7-O-ß-D-O-4-methoxyglucopyranoside (14). Chaetomium cochloides (ATCC 10195) also transformed 1 to 2, 3, 9, together with 7-hydroxy-4-cis-ol (15). Mucor ramannianus (ATCC 9628) metabolized 1 in addition to 7, to also 4,2’,4’-trihydroxychalcone (16), 7,3’,4’-trihydroxy-flavanone (17), 4’-hydroxyflavanone 7-O-a-L- rhamnopyranoside (18), and 7,3’,4’-trihydroxy-6-methoxyflavanone (19). The organism Aspergillus allaiceus (ATCC 10060) transformed 1 to metabolites 3, 16, 7,8,4’-trihydroxyflavanone (20), and 7-hydroxyflavanone 4’-sulfate (21). A metabolite of 1, flavanone 7-O-ß-D-O-glucopyranoside (22) was produced by Rizopus oryzae (ATCC 11145). 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. Metabolites 4 and 16 showed weak antileishmanial activity.