Determination of Paeoniflorin in Rat Plasma by Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry and its Application to a Pharmacokinetic Study.
In this study, a rapid and highly sensitive ultra-high performance liquid chromatography-tandem mass spectrometry method was established for the quantification of paeoniflorin in rat plasma. The analyte and the internal standard (IS), hyperoside, were extracted from rat plasma via liquid-liquid extraction with ethyl acetate. LC separation was carried on a Phenomenex Luna C18 column within 2.5 min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization and operated in the multiple reaction monitoring and negative ion modes. The precursor to product ion transitions monitored for paeoniflorin and the IS were m/z 524.8→449.0 and 463.1→300.0, respectively. The assay was validated with a linear range of 0.02~25.6 μg/mL for paeoniflorin. The intra- and inter-day precisions (relative standard deviation%) were within 9.7%, and the recoveries were greater than 65.2%. Paeoniflorin was proven to be stable during all sample storage, preparation and analytical procedures. The method was successfully applied to a pharmacokinetic study of the Baixiangdan Capsule in eight female rats.
Pharmacokinetic comparisons of albiflorin and paeoniflorin after oral administration of Shaoyao-Gancao-Tang and single herb Paeony decoction to rats.
Shaoyao-Gancao-Tang (SGT) is a traditional Chinese prescription containing Radix Paeoniae alba and Radix Glycyrrhizae and is commonly used to relieve pains. Albiflorin and paeoniflorin are the main effective compounds of Radix Paeoniae alba, and the pharmacokinetic differences of the two compounds in rats after oral administration of SGT and single herb Paeony decoction were studied. At different time points (5, 10, 15, 20, 30, 45, 60, 90, 120, 180, 240, 360, and 540 min) after administration, plasma concentrations of albiflorin and paeoniflorin were determined using a simple and reliable UPLC method, and main pharmacokinetic parameters were evaluated. It was found that there were significant differences (p < 0.05 or p < 0.01) between the two groups. The results indicated that some components in the other ingredient herb of SGT (Radix Glycyrrhizae) had a pharmacokinetic interaction with albiflorin and paeoniflorin and hence reduced their systematic exposure level.
Glycogen phosphorylase in lobster hepatopancreas: action of proteases on the enzyme
Abstract 1. 1. In lobster hepatopancreas, extracellular protreases cause the inactivation of glycogen phosphorylase. 2. 2. The proteolysis of glycogen phosphorylase purified from rabbit muscle by these proteases has been shown by SDS-polyacrylamide gel electrophoresis. 3. 3. A cell isolation technique has allowed us to remove proteases of extracellular digestion and to measure glycogen phosphorylase activity in lobster hepatopancreas. 4. 4. The glycogen phosphorylase activity seems to be mainly associated with R cells while it could not be detected in B cells.