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Li X.-J.,University of Sichuan | Li X.-J.,Chengdu BaiKang Institute of Pharmacology and Toxicology | Yang K.,Chengdu BaiKang Institute of Pharmacology and Toxicology | du G.,Sichuan Provincial Institute for Food and Drug Control | And 3 more authors.
Analytical and Bioanalytical Chemistry | Year: 2015

A liquid chromatography–mass spectrometry (LC–MS) method coupled with specialized sample-preparation strategies was developed to investigate the hydrolysis of ginkgolide B (GB) in physiological environments in comparison with that of ginkgolide A (GA). The rapid hydrolysis processes were captured by the direct injection of samples prepared in the volatile buffers. The LC–MS behavior of the hydrolyzed products, including three monocarboxylates and three dicarboxylates, was acquired. The monocarboxylates were identified by fragmentation analysis, and the dicarboxylates were accordingly tentatively identified by reaction sequences. The base-catalyzed hydrolysis of GB and GA was characterized at 4 °C within pH 7.0–10.7. The regioselective reactions on the lactone-C and lactone-F were revealed by thermodynamic studies at pH 6.8 and 7.4. It was revealed that the 1-hydroxyl group on the skeleton of GB blocks the reactivity of the lactone-E. On the basis of these results, a distinctive hydrolysis phenomenon of GB was confirmed in plasma of humans, rats, and dogs as a rapid degradation of the trilactone along with the only production of the lactone-F-hydrolyzed product. This phenomenon is also closely associated with the 1-hydroxyl group, because it was not observed in GA. More interestingly, the underlying mechanism was revealed not to be associated with any typical enzyme-catalyzed process, but to be potentially involved with a selective reaction of the intact or broken lactone-C moiety with endogenous small-molecule reactants in plasma. This in-depth knowledge of the hydrolysis of GB versus GA not only facilitated understanding of their pharmacological mechanisms but also provided potential routes to study the structure–activity relationships of ginkgolides. [Figure not available: see fulltext.] © 2015 Springer-Verlag Berlin Heidelberg Source


Lv G.,Chengdu University of Traditional Chinese Medicine | Lv G.,Hong Kong Baptist University | Cheng S.,Sichuan Provincial Institute for Food and Drug Control | Chan K.,Hong Kong Baptist University | And 2 more authors.
Zhongguo Zhongyao Zazhi | Year: 2010

Ferulic acid (FA) is one of the main bioactive compounds in Chuanxiong (CX), the dried rhizome of Ligusticum chuanxiong, but its amount in this herb is difficult to determine accurately. An accurate quantificational method was developed to investigate on the available amount of FA (free FA and total FA). Herbal samples were extracted in methanol-formic acid (95:5) and methanol-0.24 mol·L-1 sodium hydrogen carbonate in water (95:5), respectively and then quantitatively analyzed by HPLC method. Thirty three CX samples were quantified on free and total FA. Total FA was found more abundant than free FA with an average ratio of 2.38 (n=32) in the range of 1.03-4.98 in 32 CX herbs, and a highest ratio of 19.6 was estimated in a rhizome seedling. Results showed that total FA content would be a better marker for the quality assessment of CX herbs. Fifteen CX typical samples were collected from the trueborn cultivating areas in Sichuan province of China. The amount of total FA in these herbs was estimated to be 1.42 mg·g-1 (n=15). The proposed limit of total FA in CX samples should not less than 1.25 mg·g-1 calculated on the dried basis. It was also found that the level of total FA was related to the quality, processing method and store duration of CX samples. Source


Xue J.,Chinese National Institute for the Control of Pharmaceutical and Biological Products | Zou W.-B.,Chinese National Institute for the Control of Pharmaceutical and Biological Products | Cui X.-W.,Sichuan Provincial Institute for Food and Drug Control | Ma W.-L.,Beijing Pharmaceutical Association | And 2 more authors.
Chinese Journal of New Drugs | Year: 2011

Objective: To compare the quality of generic drugs manufactured by domestic pharmaceuticals with the original product and list principles for quality evaluation of marketed drugs with metformin hydrochloride tablets as an example. Methods: Based on three basic elements of drugs (safety, efficacy and quality control), comparison and evaluation of the quality were performed on related substances, dissolution and content, which closely related to clinical efficiency. Results: In related substances and content, domestically produced generic drugs and the original product were equivalent, but there were differences on dissolution. Conclusion: Compared with the original product, the safety and quality control of domestically produced generic drugs are satisfactory. However, whether the in vivo bioavailability, clinical efficiency and side effects of some domestic samples are entirely consistent with the original product or not will be further explored. Source


Li X.-J.,University of Sichuan | Li X.-J.,Chengdu BaiKang Institute of Pharmacology and Toxicology | Yang K.,Chengdu BaiKang Institute of Pharmacology and Toxicology | Du G.,Sichuan Provincial Institute for Food and Drug Control | And 2 more authors.
Analytical and bioanalytical chemistry | Year: 2015

A liquid chromatography-mass spectrometry (LC-MS) method coupled with specialized sample-preparation strategies was developed to investigate the hydrolysis of ginkgolide B (GB) in physiological environments in comparison with that of ginkgolide A (GA). The rapid hydrolysis processes were captured by the direct injection of samples prepared in the volatile buffers. The LC-MS behavior of the hydrolyzed products, including three monocarboxylates and three dicarboxylates, was acquired. The monocarboxylates were identified by fragmentation analysis, and the dicarboxylates were accordingly tentatively identified by reaction sequences. The base-catalyzed hydrolysis of GB and GA was characterized at 4 °C within pH 7.0-10.7. The regioselective reactions on the lactone-C and lactone-F were revealed by thermodynamic studies at pH 6.8 and 7.4. It was revealed that the 1-hydroxyl group on the skeleton of GB blocks the reactivity of the lactone-E. On the basis of these results, a distinctive hydrolysis phenomenon of GB was confirmed in plasma of humans, rats, and dogs as a rapid degradation of the trilactone along with the only production of the lactone-F-hydrolyzed product. This phenomenon is also closely associated with the 1-hydroxyl group, because it was not observed in GA. More interestingly, the underlying mechanism was revealed not to be associated with any typical enzyme-catalyzed process, but to be potentially involved with a selective reaction of the intact or broken lactone-C moiety with endogenous small-molecule reactants in plasma. This in-depth knowledge of the hydrolysis of GB versus GA not only facilitated understanding of their pharmacological mechanisms but also provided potential routes to study the structure-activity relationships of ginkgolides. Graphical Abstract Regioselective hydrolysis of ginkgolide B in pH 7.4 buffers and plasma. Source


Wang A.-Q.,University of Sichuan | Wei B.-P.,Sichuan Provincial Institute for Food and Drug Control | Zhang Y.,University of Sichuan | Wang Y.-J.,University of Sichuan | And 2 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2011

For the endogenous substances with an ultra-low level in biological fluids, such as melatonin, the blank biological matrix is obviously not " blank" This problem leads to a serious issue of the bioanalytical methods development and validation by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This work developed and validated an ultra-high sensitive bioanalytical method for plasma melatonin by LC-MS/MS using water as calibration matrix. The lower limit of quantitation of the method was verified to be 1.0. pg/mL and the method exhibited a linear range of 1-5000. pg/mL. Potential matrix effects, accuracy and precision were fully monitored and validated by two complementary quality control approaches respectively using water and the pooled plasma as matrix. The intra-run and inter-run precisions were less than 11.5% and 12.2%, respectively, and the relative error was below ±13.8% for all of 5 quality control levels. The method was successfully applied to investigate the daytime (8:00. AM-8:00. PM) baseline level of endogenous plasma melatonin, as well as the pharmacokinetic profiles of exogenous melatonin after oral administration in beagle dogs. © 2011 Elsevier B.V. Source

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