Abstract
Ethnopharmacological relevance Flavokawain A, the major chalcone in kava extracts, was served as beverages for informal social occasions and traditional ceremonials in most South Pacific islands. It exhibited strong antiproliferative and apoptotic effects against human prostate and urinary bladder cancer cells. Aim of the study The current study was purposed to investigate the interaction between Flavokawain A and Cytochrome P450, including the inhibitory effects of Flavokawain A on predominant CYP450 isotypes and further clarified the inhibitory mechanism of FKA on CYP450 enzymes. Besides, study about identifying the key CYP450 isotypes responsible for the metabolism of FKA was also performed. Materials and methods In this study, probe-based assays with rat liver microsome system were used to characterize the inhibitory effects of FKA. Molecular docking study was performed to further explore the binding site of FKA on CYP450 isoforms. In addition, chemical inhibition experiments using specific inhibitors (a-naphthoflavone, quinidine, sulfamethoxazde, ketoconazole, omeprazole) were performed to clarify the individual CYP450 isoform that are responsible for the metabolism of FKA. Results FKA showed significant inhibition on CYP1A2, CYP2D1, CYP2C6 and CYP3A2 activities with IC50 values of 102.23, 20.39, 69.95, 60.22 μmol/L, respectively. The inhibition model was competitive, mixed-inhibition, uncompetitive, and noncompetitive for CYP1A2, CYP2D1, CYP2C6 and CYP3A2 enzymes. Molecular docking study indicated the ligand-binding conformation of FKA in the active site of CYP450 isoforms. The chemical inhibition experiments showed that the metabolic clearance rate of Flavokawain A decreased to 19.84%, 50.38%, and 67.02% of the control in the presence of ketoconazole, sulfamethoxazde and a-naphthoflavone. Conclusion The study showed that Flavokawain A has varying inhibitory effect on CYP450 enzymes and CYP3A2 was the principal CYP isoform contributing to the metabolism of Flavokawain A. Besides, CYP2C6 and CYP1A2 isoforms also play important roles in the metabolism of FKA. Our results provided a basis for better understanding the biotransformation of FKA and prediction of drug-drug interaction of FKA.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 350-359 |
| Number of pages | 10 |
| Journal | Journal of Ethnopharmacology |
| Volume | 191 |
| DOIs | |
| State | Published - Sep 15 2016 |
| Externally published | Yes |
Bibliographical note
Funding Information:FKA was provided by Sigma (St. Louis, MO). Dextromethorphan, phenacetin, diclofenac sodium, simvastatin and omeprazole were supplied by Aladdin Regent Company (Shanghai, China). A-naphthoflavone, quinidine, sulfamethoxazole, ketoconazole and omeprazole were supported by Tianjing technology company (Tianjing, China). The other reagents (potassium phosphate, NADPNa 2 , glucose-6-phosphate, glucose-6-phosphate dehydrogenase) were obtained from Beijing Dingguo Changsheng Company (Beijing, China). All the solvents used were HPLC grade and purchased from Chemical Reagent Company, Ltd. (Tianjin, China).
Funding Information:
This study was supported by National Natural Science Foundation of China (Project No. 21403200 ). The authors would like to thank Xia Xu for her experimental support.
Publisher Copyright:
© 2016 Elsevier Ireland Ltd
Keywords
- Cytochrome P450
- Flavokawain A
- Metabolism
- Molecular docking
- Rat liver microsome
