Thymoquinone Increased Warfarin 7-hydroxylation in Human Liver Microsomes and Induced the Expression of CYP2C9 in HepG2 Cells

The herbal-drug interaction is an interesting phenomenon that can induce therapeutic complications in patients. Warfarin is widely used as an anticoagulant, which has a narrow therapeutic index. The combination of herbal and warfarin has consequences in the outcome therapy on the attenuation of drug efficacy or increased toxicity. This study aims to investigate the effect of thymoquinone on warfarin 7-hydroxylation activity in human liver microsome (HLM) and the expression of CYP2C9 in HepG2 cells. To investigate the co-administration of thymoquinone on warfarin 7-hydroxylation was conducted using HLM and HepG2 cells. The study was divided into three groups: control, warfarin, and combination of warfarin-thymoquinone. The metabolite of 7-hydroxywarfarin (7-OH warfarin) in HLM was determined using HPLC-MS/MS. Furthermore, the induction effect of thymoquinone on the expression of CYP2C9 in HepG2 cells was determined by RT-PCR. The results of the validated method used were selective for HLM 7-hydroxywarfarin, with an LLOQ of 0.62 μM, and it meets the criteria for accuracy and precision for metabolite analysis. The results showed that the co-incubation of thymoquinone at 0.37mM significantly increased warfarin 7-hydroxylation activity (P < 0.05). In addition, the incubation for 72 hours of thymoquinone also significantly induced the expression of CYP2C9 in HepG2 cells (P < 0.05). These findings provide valuable insights that the combination of thymoquinone with warfarin significantly increased the warfarin 7-hydroxylation activity in human liver microsomes and expression of the CYP2C9 in HepG2 cells, which may have an impact on the clinical outcomes of warfarin in patients.