Research On The Inhibition Of CYP3A4 By Flavonoids Derivatives And Their Inhibitory Relationship

Objective:1)To evaluated the potential inhibition of 44 different types of common flavonoids from herbal medicines and dietary supplements toward CYP3A4 and other CYPs isoforms in vitro;2)To investigate the inhibitory characteristics of flavonoids and explain the underlying mechanism of flavonoids inhibiting CYP3A4;3)To develop a quantitative structure-activity relationship(QSAR)model for illustrating the vital relationship between the chemical structures and their inhibitory activity toward CYP3A4,and further predict the potential DDI.Methods:1)Use in vitro incubation system,to evaluate the potential inhibition of 44different types of common flavonoids toward CYP3A4 and other CYPs isoforms;2)Analysis the inhibition kinetics of CYP3A4 inhibited by flavonoids;3)Evaluate the DDI between flavonoids and clinical drugs metabolized by CYP3A4 in pooled human liver microsomes(HLM)and human primary hepatocytes;4)Built a quantitative structure-activity relationship(QSAR)model for predicting the DDI risk.Results:A remarkable structure-dependent inhibition behavior toward CYP3A4 was observed in vitro and the screening of different CYP isoforms showed that they also inhibited CYP1A2,CYP2C9 and CYP2C19 to some extent.Some flavonoids such as icoflavone(12)and irilone(30)exhibited the selective inhibition toward CYP3A4rather than other major human CYPs.Sophoranone(1),apigenin(10),baicalein(11),5,4’-dihydroxy-3,6,7,8,3’-pentamethoxyflavone(15),myricetin(23)and kushenol K(38)remarkably inhibited the CYP3A4-catalyzed bufalin 5’-hydroxylation reaction,with K_i values of 2.17±0.29μM,6.15±0.39μM,9.18±3.40μM,2.30±0.36μM,5.00±2.77μM and 1.35±0.25μM,respectively.Importantly,compounds 1、11、15、23 and38 could significantly inhibit the metabolism of some clinical drugs(loratadine、gefitinib、midazolam、nifedipine、diazepam and tamoxifen)in vitro,and these herb-drug interactions(HDIs)of myricetin(23)or kushenol K(38)with clinical drug diazepam were further verified in human primary hepatocytes,respectively.Finally,a quantitative structure-activity relationship(QSAR)of flavonoids with their inhibitory effects toward CYP3A4 was established using computational methods.Our findings revealed the vital structures requirement of natural flavonoids for the HDIs with clinical drugs eliminated by CYP3A4.Conclusion:This study showed that flavonoid derivatives had significant inhibitory effects on CYP3A4.Among them,licoflavone(12)and irilone(30)had strong inhibitory effects on CYP3A4,which were highly selective inhibitors of CYP3A4.Additionally,the inhibitory type of sophoranone(1)toward CYP3A4 was verified to be competitive inhibition;apigenin(10)was uncompetitive inhibition;baicalein(11)、5,4’-dihydroxy-3,6,7,8,3’-pentamethoxyflavone(15)、myricetin(23)and kushenol K(38)toward CYP3A4 were mixed-type inhibition.These flavonoid derivatives could also significantly inhibit the metabolism of some clinical drugs eliminated by CYP3A4,which indicated herb-drug interactions would be occurred in the co-administration.Furthermore,the structure-activity relationship of flavonoids toward CYP3A4 was successfully established by the CoMFA(Comparative Molecular Field Analysis)model.Our findings could give some useful guidance for the rational use of common herbs or daily ingredients containing abundant flavonoids.