Abstract
A novel quantitative 1H NMR (Q-NMR) combined with HPLC-MS method has been proposed for investigating the degradation process of traditional Chinese medicine (TCM) components. Through this method, in-situ monitoring of dynamics degradation process of lithospermic acid (LA), one of the popular polyphenolic acids in TCM, was realized under low oxygen condition. Additionally, this methodology was proved to be simple, rapid and specific. Degradation kinetic runs have been carried out to systematically investigate the effects of two key environmental factors, initial pH values and temperatures. Eight main degradation products of LA were detected, seven of which were tentatively structural elucidated with the help of both NMR and LC-MS in this work and salvianolic acid A (Sal A) was the primary degradation product of LA. A possible degradation pathway of LA was proposed, subsequently. The results showed that the degradation of LA followed pseudo-first-order kinetics. The apparent degradation kinetic constants increased as the initial pH value of the phosphate buffer increased. Under the given conditions, the rate constants of overall degradation as a function of temperature obeyed the Arrhenius equation. Our results proved that the Q-NMR combined with HPLC-MS method can be one of the most promising techniques for investigating degradation process of active components in TCM.
Highlights
The chemical complexity and vagueness of effective compounds are major impediments to the development of traditional Chinese medicine (TCM) into modern medicine in comply with pharmaceutical standards accepted worldwide
A tentative assignment of the degradation products was made on basis of quasi-molecular ion [M−H]− and fragment ions obtained from LC—MSn experiments
MS quasi-molecular ion of peak 4 was the same as peak 5, according to the results in previous work [4], peak 4 was identified as iso-salvianolic acid C
Summary
The chemical complexity and vagueness of effective compounds are major impediments to the development of traditional Chinese medicine (TCM) into modern medicine in comply with pharmaceutical standards accepted worldwide. Multi-components and multi-species of many TCMs are accountable for most of these challenges, the deficiencies in modern standardization and quality control methods for TCM are important contributing factors [1]. The TCM production process consists of the following indispensable units: extraction, concentration, purification, drying and preparation. Degradation Investigation of Lithospermic Acid Using Q-NMR with HPLC-MS publish, or preparation of the manuscript. Funds were used to buy materials, chemicals, and pay labor costs
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