Comparative investigation of in vitro biotransformation of 14 components in Ginkgo biloba extract in normal, diabetes and diabetic nephropathy rat intestinal bacteria matrix

Most herbal medicines will be metabolized by intestinal bacteria in the gastrointestinal tract before absorbed by the small intestine. Ginkgo biloba extract (GBE) possesses protective effects on the glomerulosclerosis of diabetic nephropathy (DN), but its biotransformation in diabetes and DN intestinal bacteria has not yet been recognized. In this work, a validated liquid chromatography-tandem mass spectrometry (LC-MS) method was established for the simultaneous quantification of 14 components in GBE in rat intestinal bacteria matrix, namely ginkgolides A, ginkgolides B, ginkgolides C, bilobalide, rutin, myricetin, quercitrin, quercetin, luteolin, genistein, kaempferol, apigenin, isorhamnetin and genkwanin. Chromatographic separation was performed on a Kromasil-C-18 (4.6 mm x 250 mm i.d., 5.0 mu m) analytical column maintained at 35 degrees C. The mobile phase was a mixture of methanol (A) and 0.1% formic acid in water (B) with a step linear gradient at a flow rate of 1.0 ml min(-1). The calibration curves of these 14 analytes demonstrated good linearity within the test range (R > 0.99). This validated method has successfully been applied into the pharmacokinetic study of the 14 components. More importantly, in the pharmacokinetic study, by comparing the time course of the biotransformation by normal, diabetes and DN rat intestinal bacteria, we found that the biotransformation speed and residence time of the 14 compounds in diabetes and DN rats differed obviously from that obtained in normal group, which provided valuable chemical information for further pharmacology and active mechanism research on GEE. (C) 2014 Elsevier B.V. All rights reserved.