Simultaneous determination of seven active ingredients in rat plasma by UPLC-MS/MS and application in pharmacokinetic studies after oral administration of scutellaria-coptis herb couple

Pharmacokinetics of B-Ring Unsubstituted Flavones

B-ring unsubstituted flavones (of which the most widely known are chrysin, baicalein, wogonin, and oroxylin A) are 2-phenylchromen-4-one molecules of which the B-ring is devoid of any hydroxy, methoxy, or other substituent. They may be found naturally in a number of herbal products used for therapeutic purposes, and several have been designed by researchers and obtained in the laboratory. They have generated interest in the scientific community for their potential use in a variety of pathologies, and understanding their pharmacokinetics is important for a grasp of their optimal use. Based on a comprehensive survey of the relevant literature, this paper examines their absorption (with deglycosylation as a preliminary step) and their fate in the body, from metabolism to excretion. Differences among species (inter-individual) and within the same species (intra-individual) variability have been examined based on the available data, and finally, knowledge gaps and directions of future research are discussed.

Simultaneous Determination of Kirenol, Rosmarinic Acid and Caffeic Acid in Rat Plasma and Pharmacokinetic Study After Oral Administration of the Extract of Manxingshizhen Preparation by UPLC-MS/MS

Introduction:

A rapid, sensitive and convenient ultra-performance liquid chromatography with tandem mass spectrometric detection (UPLC-MS/MS) method has been validated and applied to the simultaneous determination of kirenol, rosmarinic acid and caffeic acid after oral administration of the extract of Manxingshizhen preparation in rat plasma.

Materials and Methods:

Puerarin was selected as the internal standard (IS). The plasma sample preparation was pretreated by liquid-liquid extraction of the mixture with ethyl acetate. All analytes were simultaneously detected in multiple reaction monitoring (MRM) mode via both the positive electrospray ionization (ESI+) and negative electrospray ionization (ESI). In the experiment, all calibration curves revealed good linearity (r > 0.999). The LLOQ were between 0.80-2.00 ng/mL, respectively.

Besides, the intra-day and inter-day precision ranged from 6.4 to 13.8%, respectively. Moreover, the accuracy was within - 11.4% and 12.8% for all the QC levels of all analytes. The extraction recoveries of the analytes and IS in plasma at three concentration levels ranged from 88.5 to 103.2%, moreover, the matrix effects of all the analytes and the IS were found to be satisfied with the acceptable range of 89.8%-101.7%. Meanwhile, the RSD values of stability met the requirement of not more than 15%. Furthermore, the pharmacokinetic parameters of three compounds were analyzed using concentrationtime profiles.

Conclusion and Results:

Plasma concentrations of the three compounds were determined up to 24 h after oral administration, and their pharmacokinetic parameters were in agreement with previous studies. The validated method was successfully applied in a pharmacokinetic study in rat plasma after oral administration of Manxingshizhen preparation.

A New Microextraction Technique for the Assay of Alkaloids in Chinese Compound Formula-Based Polyether Sulfone Membrane Fiber Decorated by TiO2 Nanoparticles

A new nanocomposite membrane was used to clean up impurities from complex samples and the obvious synergy was obtained in this paper. The nanocomposite membrane was prepared by dispersing TiO2 nanoparticles in chloroform and filled in the pores and lumen of polyether sulfone membrane fiber. The novel microextraction method showed the ideal selective extraction effect for alkaloids in the formulae composed of Rhizoma coptidis and the excellent clean-up efficiency compared with the single membrane method. The optimum extraction conditions were as follows: chloroform as accepted phase; the number of nanocomposite membrane fiber bars, 7; extraction time, 30 min; pH of the sample solution, 10.55; desorption solvent, methanol. The limit of detection for the described alkaloids was estimated at 0.122 μg mL-1. The recovery of the four alkaloids in complex samples ranged from 93.24% to 97.94% with relative standard deviation of <4.99 (n = 5). The validated method had been successfully applied to study the transfer rate of alkaloids in the producing process of Qihuang capsule and the ideal transfer rate of alkaloids was obtained in this paper.

Electrochemical behavior of palmatine and its sensitive determination based on an electrochemically reduced l-methionine functionalized graphene oxide modified electrode

A new, sensitive voltammetric sensor for palmatine is reported, based on an electrochemically reduced l-methionine functionalized graphene oxide modified glassy carbon electrode (l-Met-ERGO/GCE).