Biotransformation of Natural and Synthetic Isoflavonoids by Two Recombinant Microbial Enzymes

<jats:title>ABSTRACT</jats:title> <jats:p> Isolation and synthesis of isoflavonoids has become a frequent endeavor, due to their interesting biological activities. The introduction of hydroxyl groups into isoflavonoids by the use of enzymes represents an attractive alternative to conventional chemical synthesis. In this study, the capabilities of biphenyl-2,3-dioxygenase (BphA) and biphenyl-2,3-dihydrodiol 2,3-dehydrogenase (BphB) of <jats:italic>Burkholderia</jats:italic> sp. strain LB400 to biotransform 14 isoflavonoids synthesized in the laboratory were investigated by using recombinant <jats:italic>Escherichia coli</jats:italic> strains containing plasmid vectors expressing the <jats:italic>bphA1A2A3A4</jats:italic> or <jats:italic>bphA1A2A3A4B</jats:italic> genes of strain LB400. The use of BphA and BphB allowed us to biotransform 7-hydroxy-8-methylisoflavone and 7-hydroxyisoflavone into 7,2′,3′-trihydroxy-8-methylisoflavone and 7,3′,4′-trihydroxyisoflavone, respectively. The compound 2′-fluoro-7-hydroxy-8-methylisoflavone was dihydroxylated by BphA at <jats:italic>ortho</jats:italic> -fluorinated and <jats:italic>meta</jats:italic> positions of ring B, with concomitant dehalogenation leading to 7,2′,3′,-trihydroxy-8-methylisoflavone. Daidzein (7,4′-dihydroxyisoflavone) was biotransformed by BphA, generating 7,2′,4′-trihydroxyisoflavone after dehydration. Biotransformation products were analyzed by gas chromatography-mass spectrometry and nuclear magnetic resonance techniques. </jats:p>