Effects of an aqueous-ethanolic extract of ginger on cytochrome P450 enzyme-mediated drug metabolism.

Ginger has been extensively used as a herbal medicine for thousands of years in Asia; it has also been used as a seasoning agent in several foods and beverages worldwide. In this study, the effect of an aqueous-ethanolic extract of ginger on CYP450-mediated drug metabolism was investigated in vitro to elucidate the herb-drug interactions. A CYP450-specific substrates mixture was incubated with an aqueous-ethanolic extract of ginger in human liver microsomes fortified with an NADPH-generating system, and the metabolites generated from each of the CYP450-specific metabolic reactions were measured by liquid chromatography-tandem mass spectrometry. The ginger extracts were tested at concentrations of 0.05-5 microg/mL. The resulting data showed that the ginger extract inhibited CYP2C19-mediated drug metabolism in a concentration-dependent manner with an IC50 value of 3.8 microg/mL. When the ginger extract was pre-incubated and assessed, the inhibition pattern did not change, indicating that the inhibition of CYP2C19 was competitive rather than mechanism-based. The effects on other CYP isozyme activity were negligible at the concentrations tested. In conclusion, this inhibitory effect of ginger extract could affect the pharmacokinetics and lead to interactions with drugs that are metabolized by CYP2C19.