Highly regioselective glucosylation of alcoholic hydroxyls of protostane triterpenoids mediated by fungal biotransformation

Article history: Received 22 August 2016 Received in revised form 7 October 2016 Accepted 23 October 2016 Available online 24 October 2016 An efficient glucosylation of alcoholic hydroxyls in the structures of protostane triterpenoids catalyzed by fungus has been developed. Four protostanes 1–4 as the substrates have been transformed by Syncephalastrum racemosumAS 3.264 and generated corresponding 11-OHglucosylation derivatives. The regioselective characteristics were also identified by various highly oxygenated protostane substrates. The time-courses displayed the highest yields of 1a, 3a, and 4a at N50%, and 1a had the highest yield of 72%. All of the protostane analogues displayed hCE-2 inhibitory effects in an in vitro bioassay. This report describes a rare biocatalytic alcoholic hydroxyl glucosylation with considerable yield and regioselective characteristics. © 2016 Published by Elsevier B.V.