The Scientiﬁc World Journal Volume 2012, Article ID 254929, 8 pages doi:10.1100/2012/254929 The cientiﬁcWorldJOURNAL Research Article Microbial Transformations of 7-Hydroxyﬂavanone Edyta Kostrzewa-Suslow and Tomasz Janeczko Department of Chemistry, Wroclaw University of Environmental and Life Sciences, Norwida 25, 50-375 Wroclaw, Poland Correspondence should be addressed to Edyta Kostrzewa-Suslow, ekostrzew@gmail.com Received 11 October 2011; Accepted 22 December 2011 Academic Editor: Gabriella Marucci Copyright © 2012 E. Kostrzewa-Suslow and T. Janeczko. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Microbial transformations of racemic 7-hydroxyﬂavanone using strains of genus Aspergillus (A. niger KB, A. niger 13/5, A. ochraceus 456) and the species Penicillium chermesinum 113 were studied. The products of O-methylation, O-methylation along with hydroxylation at C-3 ′ and C-4 ′ , reduction of the carbonyl group, reduction of the carbonyl group along with hydroxylation at C-5, and dehydrogenation of C-2 and C-3 were obtained. Most of the products (with the exception of the O-methylation one) have stronger antioxidant properties than the initial substrate. 1. Introduction Flavonoids comprise a large group of secondary metabolites derived from phenylalanine. They are commonly found in plants, where their biogenesis takes place under normal phys- iological conditions (e.g., synthesis of pigments in ﬂowers), but also may be a part of environmental stress response (e.g., synthesis of phytoalexins) [1–3]. Although the presence of natural ﬂavonoids in animals and people has not been conﬁrmed so far, their multidirectional inﬂuence on many important processes in these organisms was proved and reported by several research institutes all over the world [4–7]. Among many review articles about ﬂavonoids, the following two: “The Flavonoids”[8] and “The Handbook of Natural Flavonoids”[1], are particularly rich in information. They present a couple of thousands of known compounds of this group, including their structures, separation methods, and identiﬁcation details. On the basis of many cited papers the authors describe chemical and biological properties of ﬂavonoids, including their inﬂuence on capillary vessels structure, on functioning of heart, liver, and kidneys. They also report diuretic, antibacterial, antiviral, immunomodu- latory, anticancer, hypoglycemic, and antioxidant properties of ﬂavonoids. Practical application of ﬂavonoids in pharmacy or in medicine is often considerably limited due to their low solu- bility, ineﬃcient transport across biological membranes or low stability. Biotransformation of ﬂavonoid compounds may be a natural method of modiﬁcation of their structures, aiming at greater structural diversity and better bioaccessibil- ity. It also gives a possibility to trace metabolic transforma- tion of ﬂavonoids [9–12]. Enzymatic systems of microorganisms are capable of dif- ferent reactions, including hydrolysis, carbonyl group reduc- tion, hydroxylation, O-methylation, oxidation, isomeriza- tion, and also formation or breakage of C–C and C–hetero- atom bonds [13, 14]. Ibrahim and Abul-Hajj described biotransformation of monohydroxyﬂavones with substituents in the A-ring us- ing the strain of Streptomyces fulvissimus (NRRL 1453B). They obtained products of hydroxylation at 4 ′ or both 3 ′ and 4 ′ positions in the B-ring. They have also observed that the distance between the carbonyl and hydroxyl groups in the A-ring has impact on the reaction speed and eﬃciency [15]. Herath and coworkers transformed 7-hydroxyﬂa- vone into 7,4 ′ -dihydroxyﬂavone by means of the strain of A. alliaceus (ATCC 10060), whereas, using the strain of Beauveria bassiana (ATCC 7159) led to formation of 7-O-β- D-4-O-Methylglucopyranoside and 4 ′ -hydroxyﬂavone 7-O- β-D-4-O-methylglucopyranoside. O-methylation of 7-hy- droxyﬂavone was catalyzed by Nocardia species (NRRL 5646). The other substrate—3-hydroxyﬂavone—was trans- formed by means of B. bassiana (ATCC 13144) into 3,4 ′ - dihydroxyﬂavone and ﬂavone 3-O-β-D-4-O-methylgluco- pyranoside [16]. The same strain metabolized 5-hydroxy- ﬂavone into 5,4 ′ -dihydroxyﬂavone and 4 ′ -hydroxyﬂavone 5-