Search

Abstract Ginkgo biloba leaves extract (GBE), one of the most widely used traditional Chinese medicines worldwide, can be used for the treatment of diabetes mellitus (DM). However, its biotransformation in liver is not fully known under the state of DM. In this study, an off-line hydrophilic interaction × reversed-phase two-dimensional liquid chromatography (HILIC × RP 2D-LC) system coupled with diode array detection (DAD) and quadrupole time-of-flight mass spectrometry (q/TOF-MS) was established for the qualification and quantification of the biotransformation of GBE in normal and diabetic rat liver microsomes (RLMs). 6 metabolites were tentatively identified according to the exact molecular weights and the characteristic fragment ions provided by q/TOF-MS data. The results of metabolic stability showed that the metabolic ratio of four target compounds including quercetin, genistein, kaempferol and isorhamnetin in diabetic RLMs were significantly enhanced when comparing with normal RLMs. The results of enzyme kinetics showed that compared with normal RLMs, the Michaelis-Menten constant (K m) value of genistein was obvious increased while its maximal velocity (V max) and intrinsic clearance (CL int) values were significantly decreased by diabetic RLMs, and the V max and CL int values of kaempferol and isorhamnetin were notably enhanced while their K m values were markedly reduced. For the half-time (t 1/2) values of four target compounds and the K m , V max and CL int values of quercetin, there were not statistically significant changes between normal and diabetic RLMs. The results suggest that the developed off-line 2D LC-DAD-q/TOF-MS method is an easy and accurate approach for the study of GBE biotransformation in RLMs and may provide the essential data for further pharmacological and clinical studies of GBE. Highlights • The biotransformation of GBE in diabetic rat liver microsomes (RLMs) was first investigated. • An off-line 2D LC-DAD-q/TOF-MS was first developed and optimized for the analysis. • 6 mono-glucuronide conjugation metabolites were tentatively characterized. • The metabolic stability of quercetin, genistein, kaempferol and isorhamnetin in diabetic RLMs was obtained. • The enzyme kinetics of quercetin, genistein, kaempferol and isorhamnetin in diabetic RLMs was first reported. [ABSTRACT FROM AUTHOR]

The mesangial cell (MC) cultured with high glucose has been used to observe the protective effect of Ginkgo biloba extract (GBE) against diabetic nephropathy (DN), but the compounds interacting with cell are still unknown, which may be potential bioactive components. Based on this, the determination of GBE in MC lysates was proposed by high performance liquid chromatography tandem mass spectrometry (LC–MS/MS) in this study. The MC was cultured with normal or high glucose with GBE for 4, 8, 12, 16, 24 and 48 h. The harvested cell was extracted with 40% acetic acid in water and further analyzed by LC–MS/MS. All the validation data including linearity, intra-day and inter-day precision, limit of detection and quantification, matrix effect, and stability were within the required limits. The validated method was successfully applied to quantify 11 compounds of GBE in cell lysates. The results showed that high glucose prolonged the peak time of all observed 11 compounds and peak concentrations of bilobalide, ginkgolide C, ginkgolide B, quercetin, luteolin, kaempferol, isorhamnetin and genkwanin in cell lysates, which hinted that these compounds may be the potential bioactive components of GBE with preventive effect against DN. [ABSTRACT FROM AUTHOR]

In this study, two independent and complementary liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were respectively developed and validated for the determination of edaravone or taurine in rat urine, feces and bile after intravenous administration, using 3-methyl-l- p -tolyl-5-pyrazolone and sulfanilic acid as the internal standards (IS). Edaravone was separated on an Agilent Eclipse Plus C 18 column (100 × 2.1 mm, 3.5 μm) using methanol and water (containing 5 mM ammonium formate and 0.02% formic acid) as mobile phase, while taurine was performed on a Waters Atlantis HILIC Silica column (150 × 2.1 mm, 3 μm) using acetonitrile and water (containing 5 mM ammonium formate and 0.2% formic acid) as mobile phase. The mass analysis was performed in a Triple Quadrupole mass spectrometer via multiple reaction monitoring (MRM) with negative ionization mode. The optimized mass transition ion pairs ( m/z ) for quantification were 173.1→92.2 and 187.2→106.0 for edaravone and its IS, 124.1→80.0 and 172.0→80.0 for taurine and its IS, respectively. The validated methods have been successfully applied to the excretion and metabolism interaction study of edaravone and taurine in rats after independent intravenous administration and co-administration with a single dose. The results demonstrated that there were no significant alternations on the metabolism and cumulative excretion rate of edaravone and taurine, implying that the proposed combination therapy was pharmacologically viable. [ABSTRACT FROM AUTHOR]