Comparative Study on Transformation of Tecomin by Using Liver Microsomes and Liver S9 QIAO Shan-shan, / 中国中医药信息杂志

Objective To compare the difference of transformation profile and transformation rate of tecomin by using two in vitro liver metabolism models. Methods Liver microsomes and liver S9 fraction models were employed to transform tecomin. HPLC was used to determine the contents of tecomin and its metabolites at the detecting wavelength of 254 nm. The gradient elution (0–6 min, 5％–40％ A; 6–9 min, 40％–50％ A; 9–11 min, 50％–5％ A) was carried out by using mobile phase of acetonitrile (A) - 1％ acetic acid (B) at a flow rate of 1 mL/min. Results Both models could transform tecomin into veratric acid; however, the metabolites obtained with liver S9 were more than those obtained with liver microsomes, and the transformation rate of the former was higher than that of the latter. Conclusion The liver S9 fraction can more efficiently transform esters than liver microsomes.

Liquid Chromatography-Mass Spectrometry-Based In Vitro Metabolic Profiling Reveals Altered Enzyme Expressions in Eicosanoid Metabolism

BACKGROUND: Eicosanoids are metabolites of arachidonic acid that are rapidly biosynthesized and degraded during inflammation, and their metabolic changes reveal altered enzyme expression following drug treatment. We developed an eicosanoid profiling method and evaluated their changes on drug treatment. METHODS: Simultaneous quantitative profiling of 32 eicosanoids in liver S9 fractions obtained from rabbits with carrageenan-induced inflammation was performed and validated by liquid chromatography-mass spectrometry coupled to anion-exchange solid-phase purification. RESULTS: The limit of quantification for the devised method ranged from 0.5 to 20.0 ng/mg protein, and calibration linearity was achieved (R 2>0.99). The precision (% CV) and accuracy (% bias) ranged from 4.7 to 10.3% and 88.4 to 110.9%, respectively, and overall recoveries ranged from 58.0 to 105.3%. Our method was then applied and showed that epitestosterone treatment reduced the levels of all eicosanoids that were generated by cyclooxygenases and lipoxygenases. CONCLUSIONS: Quantitative eicosanoid profiling combined with in vitro metabolic assays may be useful for evaluating metabolic changes affected by drugs during eicosanoid metabolism.

Study on sulfation metabolism of scutellarein in FVB/NCrIVr mice / 中国药学杂志

OBJECTIVE: To investigate the characteristics of sulfation of scutellarein in FVB/NCrIVr (FVB) mice. METHODS: FVB mouse intestinal perfusion model and incubation system with FVB mouse liver S9 fractions were adapted to conduct the study. HPLC-MS/MS and HPLC-UV were used to identify and quantify scutellarein and its metabolites in the samples. RESULTS: One sulfation metabolite and one glucuronidation metabolite were detected in the small intestinal perfusate. There was no significant difference between the excretion rates of sulfation metabolite and glucuronidation metabolite in small intestinal perfusate (P=0.435), while only sulfation metabolite of scutellarein could be detected in colon perfusate, scutellarein, sulfation metabolite and glucuronidation metabolite of scutellarein could all be detected in biliary samples, indicating an entero-hepatic circulation of scutellarein. In the liver S9 fractions, sulfation rate at 20 μmol·L-1 was sig nificantly higher than those at 10 and 40 μmol·L-1 (P<0.05). CONCLUSION: Sulfation was found to be the most important metabolism route in the intestinal disposition of scutellarein. There is probably a substrate inhibition effect in the sulfation of scutellarein in liver S9 fractions.