Biological Synthesis of Baicalein Derivatives Using .

Two baicalein derivatives, baicalin and oroxylin A, were synthesized in this study. These derivatives exhibit diverse biological activities, such as anxiolytic and anticancer activities as well as memory enhancement. In order to synthesize baicalin from aglycon baicalein using , we utilized a glycosyltransferase that regioselectively transfers glucuronic acid from UDP-glucuronic acid to the 7-hydroxy group of baicalein. To increase baicalin productivity, an deletion mutant, which accumulates UDP-glucuronic acid, was used, and , which converts UDP-glucose to UDP-glucuronic acid, was overexpressed. Using these strategies, approximately 720.3 µM baicalin was synthesized from 1,000 µM baicalein. Oroxylin A was then synthesized from baicalein. Two -methyltransferases (OMTs), ROMT-15 and POMT-9, were tested to examine the production of oroxylin A from baicalein. harboring and harboring produced reaction products that had different retention times, indicating that they are methylated at different positions; the structure of the reaction product from POMT-9 was consistent with oroxylin A, whereas that from ROMT-15 was 7--methyl baicalein. Using harboring , approximately 50.3 mg/l of oroxylin A (177 µM) was synthesized from 54 mg/l baicalein (200 µM).