Potential Determinants for Metabolic Fates and Inhibitory Effects of Isobavachalcone Involving in Human Cytochrome P450, UDP-Glucuronosyltransferase Enzymes, and Efflux Transporters

Isobavachalcone, a naturally occurring chalcone in Psoralea corylifolia, posses many biological properties including anticancer, antiplatelet, and antifungal. However, its glucuronidation, glucuronides excretion, and drug-drug interaction (DDI) involving in human cytochrome P450 (CYP), UDP-glucuronosyltransferase (UGT) enzymes, and efflux transporters (BCRP and MRPs) remains unclear so far. After incubation, three glucuronides were produced by HLM and HIM with total intrinsic clearance (CLint) of 236.71 and 323.40 μL/min/mg, respectively. Reaction phenotyping proved UGT1A1, 1A3, 1A7, 1A8, and 1A9 played important roles in glucuronidation with total CLint values of 62.69-143.00 μL/min/mg. Activity correlation analysis indicated UGT1A1 and UGT1A3 participated more in the glucuronidation. In addition, the glucuronidation showed marked species differences, and rabbits and dogs were probably appropriate model animals to investigate the in vivo glucuronidation. Furthermore, BCRP, MRP1, and MRP4 transporters were identified as the most important contributors to glucuronides excretion in HeLa1A1 cells based on gene silencing method. Moreover, isobavachalcone demonstrated broad-spectrum inhibitory effects against CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, UGT1A1, UGT1A9, UGT2B7 with IC50 values of 1.08-9.78 μM. Except CYP2B6 and CYP2D6, the calculated [I]/Ki values for other enzymes were all greater than 0.1, indicating the inhibition of systemic metabolism or elimination for these enzyme substrates seems likely. Taken together, we summarized metabolic fates of isobavachalcone including glucuronidation and efflux transport as well as inhibitory effects involving in human CYP and UGT enzymes.