No abstract

Cytochrome P450 (CYP) is a critical drug-metabolizing enzyme superfamily. Modulation of CYP enzyme activities has the potential to cause drug–drug/herb interactions. Drug–drug/herb interactions can lead to serious adverse drug reactions (ADRs) or drug failures. Therefore, there is a need to examine the modulatory effects of new drug entities or herbal preparations on a wide range of CYP isoforms. The classic method of quantifying CYP enzyme activities is based on high-performance liquid chromatography (HPLC), which is time- and reagent-consuming. In the past two decades, high-throughput screening methods including fluorescence-based, luminescence-based, and mass-spectrometry-based assays have been developed and widely applied to estimate CYP enzyme activities. In general, these methods are faster and use lower volume of reagents than HPLC. However, each high-throughput method has its own limitations. Investigators may make a selection of these methods based on the available equipment in the laboratory, budget, and enzyme sources supplied. Furthermore, the current high-throughput systems should look into developing a reliable automation mechanism to accomplish ultra-high-throughput screening in the near future.

Background: Mangiferin has been identified as one of the major active constituents of Aquilaria plants. It was reported to have several promising chemotherapeutic potentials. Our preliminary data suggested that Aquilaria plant water extracts inhibited several cytochrome P450 (CYP) isoenzymes in vitro. Objective: This study aimed to investigate the modulatory effects of mangiferin on six major drug metabolizing CYP enzymes including CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP3A4, and CYP3A5. Methods: The enzyme activities were measured using fluorescence-based assays and enzyme kinetic such as IC50 parameters and Ki values were calculated to evaluate inhibitory potencies and mechanisms. Moreover, for potent inhibitions, molecular docking studies were carried out to explore potential interactions of residues between mangiferin and CYP enzymes. Results: Our findings suggested that mangiferin could inhibit CYP2D6, CYP3A4, and CYP3A5 in vitro with IC50 values of 9.2, 8.7, and 4.3µM, and Ki values of 3.8, 10.8, and 9.6µM, in a non-competitive inhibition pattern. Molecular docking studies using AutoDock 4.2 identified potential residues contained in mangiferin that interacted with CYP2D6, CYP3A4, and CYP3A5, resulting in the observed inhibitory effects. Conclusion: Mangiferin should be used carefully, in particular, with conventional drugs metabolized mainly by CYP2D6, CYP3A4, and CYP3A5. Further in vivo studies are recommended to evaluate the clinical relevance of these inhibitions.