Pharmacokinetics, tissue distribution, in vivo metabolism and liver microsomal metabolism of GK-A, GK-2 and Eucomic acid in rats were studied by liquid chromatography-tandem mass spectrometry and mass spectrometry imaging of Ginkgo Semen extract

Ethnopharmacological relevance N-[2-(1-β-D-Glucopyranosyl-1H-indol-3-yl)acetyl]-L-aspartic acid (GK-A), N-[2-(1-β-D-Glucopyranosyl-1H-indol-3-yl)acetyl]-L-glutamic acid (GK-2) and Eucomic acid are the main active components of Ginkgo Semen , which have strong antitussive effects. However, the pharmacokinetics, tissue distribution, metabolism, and in vitro liver microsome stability of these components in rats remain unstudied. Aim of the study Comprehensive evaluation of the pharmacokinetics, tissue distribution, in vitro liver microsomal stability, and in vivo metabolic behavior of GK-A, GK-2, and Eucomic acid in Ginkgo Semen extract (GSE). Materials and methods A very rapid and highly sensitive LC-MS/MS approach was established to study the pharmacokinetics of orally administered GSE (80 mg/kg) and quantify GK-A, GK-2, and Eucomic acid in various tissues. DESI-MSI was utilized to clearly visualize the spatial distribution of GK-A, GK-2, and Eucomic acid in lung tissue, while UPLC-Q-TOF-MS analyzed the metabolic profiles of GK-A, GK-2, and Eucomic acid in rat plasma and excreta. Results GK-A, GK-2, and Eucomic acid reached T max within 2 h, with MRT 0-t under 4 h following oral GSE administration. GK-A and GK-2 were present in all tissues except the brain, while Eucomic acid was also detected in brain tissue. All three compounds showed high concentrations in the small intestine, kidneys, stomach, and liver. They were metabolized slowly and poorly in liver microsomes from cynomolgus monkeys, rats, dogs, and humans. In total, 14 GK-A metabolites, 8 GK-2 metabolites, and 8 Eucomic acid metabolites were identified in plasma, urine, and feces. Conclusions GK-A, GK-2 and Eucomic acid were all rapidly absorbed by plasma and widely distributed in tissues after oral administration of GSE. There was no accumulation of GK-A, GK-2 and Eucomic acid in the tissues, and the content in the small intestine, kidney, stomach and liver was higher. And Eucomic acid was able to cross the blood-brain barrier, and CYP450 enzyme in the liver was not the main metabolizing enzyme of the extract. GK-A, GK-2 and Eucomic acid were excreted in the feces and urine of the rats, and at the same time, were converted into other metabolites by the rats to be eliminated from the body. The results of this study lay a foundation for the further development and application of GSE.