Glucuronidation of the broad-spectrum antiviral drug arbidol by UGT isoforms

Objectives The aim of this work was to identify the uridine glucuronosyltransferase (UGT) isoforms involved in the metabolism of the broad-spectrum antiviral drug arbidol. Methods A human liver microsome (HLM) incubation system was employed to catalyse the formation of arbidol glucuronide. The glucuronidation activity of commercially recombinant UGT isoforms towards arbidol was screened. A combination of kinetic analysis and chemical inhibition study was used to determine the UGT isoforms involved in arbidol's glucuronidation. Key findings The arbidol glucuronide was detected when arbidol was incubated with HLMs in the presence of UDP-glucuronic acid. The EadieHofstee plot showed that glucuronidation of arbidol was best fit to the MichaelisMenten kinetic model, and Km and apparent Vmax were calculated to be 8.0 +/- 0.7m and 2.03 +/- 0.05nmol/min/mg protein, respectively. Assessment of a panel of recombinant UGT isoforms revealed that UGT1A1, UGT1A3 and UGT1A9 could catalyse the glucuronidation of arbidol. Kinetic analysis and chemical inhibition study demonstrated that UGT1A9 was the predominant UGT isoform involved in arbidol glucuronidation in HLMs. Conclusions The major contribution of UGT1A9 towards arbidol glucuronidation was demonstrated in this study.