Determination of YZG-331 in mouse plasma using liquid chromatography-tandem mass spectrometry

Simultaneous determination of YZG-331 and its metabolites in monkey blood by liquid chromatography-tandem mass spectrometry

N6-[(S)-1- (phenyl)-propyl]-adenine riboside (YZG-331) is being developed as a novel sedative and hypnotic agent. The hydroxylated metabolites of YZG-331 have the same mass transition ion pair, making their determination in blood challenging. In this study, a rapid and sensitive liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of YZG-331 and its metabolites M1 (hydrolysis), M2 and M4 (hydrolysis and hydroxylation), M3, M5 and M6 (hydroxylation) in monkey blood. Propranolol was used as the internal standard (IS). Blood samples were prepared using a simple protein precipitation with acetonitrile. The chromatographic separation was performed on an Eclipse Plus C18 column (2.1 × 50 mm, 3.5 μm) at a flow rate of 0.3 mL/min with a gradient mobile phase of methanol/water containing 0.5 % formic acid (v/v). Detection was carried out on a triple quadrupole mass spectrometer in positive ion multiple reaction monitoring mode. The optimized mass transition ion pairs for quantitation were 386→254 for YZG-331, 254→136 for M1, 270→136 for M2 and M4, 402→136 for M3, M5 and M6 and 260→183 for IS. Acceptable linearity was obtained for the analytes over the range of 15-2000 ng/mL for YZG-331, 3-400 ng/mL for M1-M6. The lower limits of the quantification were 15 ng/mL for YZG-331, 3 ng/mL for M1-M6. The intra- and inter-day precisions wre within 10.5 % for all analytes, while the accuracy ranged from -8.3 %-8.8 %. There was no obvious matrix effect and the recoveries of the analytes were 90.6 %-118.2 %. The analytes were proved to be stable during all sample storage, preparation and analytic procedures. The sensitive and rapid LC-MS/MS method for YZG-331 in monkey blood has been applied to pharmacokinetic studies of YZG-331 in monkeys. The oral bioavailability of YZG-331 in monkeys is 74.1 %.

Interspecies Variation of In Vitro Stability and Metabolic Diversity of YZG-331, a Promising Sedative-Hypnotic Compound

YZG-331, a synthetic adenosine derivative, express the sedative and hypnotic effects via binding to the adenosine receptor. The current study was taken to investigate the metabolic pathway of YZG-331 as well as species-specific differences in vitro. YZG-331 was reduced by 14, 11, 6, 46, and 11% within 120 min incubation in human, monkey, dog, rat, and mouse liver microsomes (LMs), respectively. However, YZG-331 was stable in human, monkey, dog, rat, and mouse liver cytoplasm. In addition, YZG-331 was unstable in rat or mouse gut microbiota with more than 50% of prototype drug degraded within 120 min incubation. Interestingly, the systemic exposure of M2 and M3 in rats and mice treated with antibiotics were significantly decreased in the pseudo germ-free group. YZG-331 could be metabolized in rat and human liver under the catalysis of CYP enzymes, and the metabolism showed species variation. In addition, 3 phase I metabolites were identified via hydroxyl (M1), hydrolysis (M2), or hydrolysis/ hydroxyl (M3) pathway. Flavin-containing monooxygenase 1 (FMO1) and FMO3 participated in the conversion of YZG-331 in rat LMs. Nevertheless, YZG-331 expressed stability with recombinant human FMOs, which further confirmed the species variation in the metabolism. Overall, these studies suggested that YZG-331 is not stable in LMs and gut microbiota. CYP450 enzymes and FMOs mediated the metabolism of YZG-331, and the metabolic pathway showed species difference. Special attention must be paid when extrapolating data from other species to humans.

Analytical Techniques and Pharmacokinetics of Gastrodia elata Blume and Its Constituents

Gastrodia elata Blume (G. elata), commonly called Tianma in Chinese, is an important and notable traditional Chinese medicine (TCM), which has been used in China as an anticonvulsant, analgesic, sedative, anti-asthma, anti-immune drug since ancient times. The aim of this review is to provide an overview of the abundant efforts of scientists in developing analytical techniques and performing pharmacokinetic studies of G. elata and its constituents, including sample pretreatment methods, analytical techniques, absorption, distribution, metabolism, excretion (ADME) and influence factors to its pharmacokinetics. Based on the reported pharmacokinetic property data of G. elata and its constituents, it is hoped that more studies will focus on the development of rapid and sensitive analytical techniques, discovering new therapeutic uses and understanding the specific in vivo mechanisms of action of G. elata and its constituents from the pharmacokinetic viewpoint in the near future. The present review discusses analytical techniques and pharmacokinetics of G. elata and its constituents reported from 1985 onwards.