Structure identification and content analysis of active components in Xiaoyao pills / 药学学报

Xiaoyao pills are a famous traditional Chinese medicine collected in Welfare Pharmacy, which is a classic prescription for treating liver depression and spleen deficiency. However, its composition is complex. In order to better control the quality of Xiaoyao pills, in this study, HPLC-ion-trap time-of-flight mass spectrometry (LC-IT-TOF/MS) was used to identify the main ingredients of Xiaoyao pills, paeoniflorin, albiflorin, glycyrrhizic acid, saikosaponin A and saikosaponin B2. Then a liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed for simultaneous determination and quantification of the main compounds. Fragmentation pathways of five active components were obtained. The method was validated. Five active ingredients in Xiaoyao pills had a good linear relationship, and the values of RSD (%) of repeatability were all less than 5%, the recovery ranges were between 90% and 115%, and the values of RSD (%) of each substance were less than 10% after the sample solution is placed for 24 hours. Three batches of Xiaoyao pills (concentrated pellets) and two batches of Xiaoyao pills (water pellets) were determined, the contents of paeoniflorin in concentrated pills were more than 4.0 mg·g-1, and those in water pills were more than 2.5 mg·g-1, which was accordance with Chinese Pharmacopoeia. However, other compounds behave differently. This method has high sensitivity and reliable measurement results, which provides basis for quality control of Xiaoyao pills and material basis for pharmacology research.

Research on in vivo metabolites of Longxue Tongluo Capsules by liquid chromatography coupled with hybrid ion trap/time-of-flight mass spectrometry / 中国中药杂志

Longxue Tongluo Capsules(LTC) has good efficacy against blood stasis syndrome during the recovery period of ischemic stroke. Its main active ingredient is the phenolic extract of Chinese dragon's blood. In our previous study, the primary mass fragmentation pathways of phenolic derivatives from LTC were clarified. Herein, the metabolites in rat plasma were characterized following the oral administration of loureirin A and loureirin C using liquid chromatography coupled with hybrid ion trap/time-of-flight mass spectro-metry(LC-IT-TOF-MS), with 18 and 55 metabolites identified, respectively. On this basis, with the help of the obtained accurate molecular weight, characteristic fragment ions, reference comparison, combined with LTC database and natural products database self-created in our group, 18 prototypes and 106 metabolites were tentatively identified in rat plasma after oral gavage of LTC at a dose of 500 mg·kg~(-1). Glucuronidation, sulfonation, and methylation were major biotransformation pathways of LTC. This study preliminarily clarified the LTC constituents absorbed into blood and laid the foundation for clarifying the effective substances of LTC.

Identification of major constituents from propolis by LC-IT-TOF-MS / 中国药科大学学报

A qualitative analytical method of liquid chromatography coupled with ion trap time-of-flight mass spectrometry (LC-IT-TOF/MS) was developed for identification of major constituents in propolis from China (Shandong).The LC-IT-TOF-MS was performed on a Shim-pack VP-ODS column (2.0 mm× 150 mm,5 μm) with the mobile phase consisting of acetonitrile and water containing 0.2％ formic acid in gradient mode,and the flow rate was set at 0.3 mL/min.Negative ion mode was used for IT-TOF-MS.According to the accurate molecular weight,MS fragment pathway,comparison with the retention time of reference compounds,total 31 compounds,including twenty-five phenolic acids and six flavonoids were identified.The LC-IT-TOF-MS qualitative analysis method can be used for analyzing major components of propolis quickly and accurately.

Structure identification of related substances in doxycycline hyclate by 2D-LC-IT-TOF/MS / 中国药学杂志

OBJECTIVE: To rapidly identify the related substances in doxycycline hyclate tablets and investigate the possible degradation pathways of doxycycline hyclate solution by 2D-LC-IT-TOF/MS. METHODS: Firstly, the chromatography was carried out using the 1stD InertSustain ™C18 (4.6 mm×150 mm, 5 μm) column and a mobile phase containing a mixture of buffer solution (0.25 mol·L-1 ammonium acetate solution-0.1 mol·L-1 ethyldiaminetetraacetic acid disodium; triethyiamine=100:10:1)-acetonitrile (85:15). Solution pH was adjusted to 8.8 with glacial acetic acid. Then a InertSustain C18 (2.1 mm×50 mm, 2 μm) column was used with 0.1% formic acid-water as mobile A and 0.1% formic acid-acetonitrile as mobile B in a gradient elution mode in 2ndD. Electrospray ionization (ESI) source was tested in both positive and negative ion modes. Nebulized gas flow was 1.5 L·min-1. Dry gas flow was 10 L·min-1. The desolvation tube temperature was kept at 200℃. Related substances were characterized according to multi-level MS behaviors. The 2D-LC-IT-TOF/MS method was employed to identify the structures of impurities in forced degradation solutions and illuminate the degradation pathways of doxycycline hyclate solution. RESULTS: A total of eight related substances were detected in doxycycline hyclate tablets. Four of them had a content of more than 0.1%, and their structures were identified to be 4-epidoxycycline, metacycline, β-epidoxycycline and 2-acetyl-2-decar-bamoyldoxycycline. The solution of doxycycline hyclate easily degraded under alkaline condition and generated an open loop compound taken off the keto group. The solution was sensitive to heat, and generated 4-epidoxycycline with a little amount of 4-epi-6-epidoxycycline; but the solution was stable under illumination and acidic condition. CONCLUSION: The established method is suitable for rapid identification of impurities in doxycycline hyclate, which can be applied as a useful analytical tool for quality control and drug process optimization of doxycycline hyclate.

Study on the plasma protein binding rate of Schisandra lignans based on the LC-IT-TOF/MS technique with relative quantitative analysis / 中国天然药物

The main objective of the current study was to develop a universal method for a protein binding assay of complicated herbal components, and to investigate the possible relationship between compound polarity and protein binding using Schisadra lignans as an example. Firstly, the rat, dog and human plasma were spiked with three different concentrations of Schisandra chinensis extract (SLE), and ultramicrofiltration was used to obtain the unbound ingredients. Secondly, thirty-one Schisandra lignans in total plasma and ultrafiltered fluid were measured by LC-IT-TOFMS. Lastly, a relative exposure approach, which entailed calculating the relative concentrations of each Schisandra lignan from the corresponding calibration equation created from the calibration samples spiked with the stock solution of SLE, was applied in order to overcome the absence of authentic standards. The results showed that Schisandra lignans exhibited a high capability to bind with plasma protein, furthermore, the protein binding ratio of the lignan components increased proportionally with their individual chromatographic retention time, which indicated that the ratio of protein binding of lignans might increase accordingly with decreasing polarity. This study suggested that the compound polarity might be an important factor affecting the plasma protein binding of herbal components.