Screening Test of 5 Thai Vegetable Alcohol Extracts on Rat CYP2D6 Enzyme Activity in-vitro

Introduction: Metabolism-based herbal-drug interaction now becomes high interested issue especially in tropical countries with variety of plants. CYP2D6 is a member of cytochrome P450 enzyme involved in biotransformation of many drugs such as antipsychotic drugs and opioids. Holy basil or Ka Prao (Ocimum sanctum L.), ivy gourd or Tam Leung (Coccinia grandis), Indian mulberry leaf or Bai Yoe (Morinda citrifolia), bamboo grass or Ya Nang (Tiliacora triandra) and star gooseberry or Pak Wan Ban (Sauropus androgynus) are Thai vegetables widely consumed in Thai North Eastern area. Chance of these vegetables to cause interaction with CYP2D6-mediat drugs metabolism should be investigated for patient safety and drug efficacy. The objective of this study was to preliminary test the effect of those 5 Thai vegetable crude alcohol extracts on function of rat CYP2D6 enzyme in vitro. Materials and Method: Metabolic tests were carried out in vitro using rat liver microsome. Dextromethorphan was used as a specific CYP2D6 prove substrate whereas positive control used was cimetidine. The amount of Dexthorphan, major metabolite of Dextromethorphan, obtained from each metabolic reaction with individual crude alcohol extracts was determined by using High Performance Liquid Chromatography (HPLC). Then, the percentage of inhibition was calculated. Results: It was found that the alcohol extract of holy basil, bamboo grass, ivy gourd, star gooseberry and Indian mulberry affected on CYP2D6 enzyme function in different degrees of inhibition ranking from low to high (4.86, 5.48, 11.74, 22.46 and 65.65 % inhibition respectively). Conclusion: It could be conclude that all 5 Thai vegetables inhibit CYP2D6 function in different degrees. The aqueous and hexane extracts of these herbs should be further investigated.