Dynamic changes in composition of extracts of natural products as monitored by in situ NMR

Phenolic Compounds and Sesquiterpene Lactones Profile in Leaves of Nineteen Artichoke Cultivars

Leaves of globe artichoke are food industry byproducts gaining interest due to their therapeutic and nutraceutical potential. The total phenolics, flavonoids, and flavonols content as well as radical scavenging capacity and reducing antioxidant power were determined in leaves of 19 artichoke cultivars. An untargeted analysis based on high-resolution mass spectrometry was then carried out to profile phenolic compounds and sesquiterpene lactones (STLs). The phenolic profile of leaf extracts from different cultivars was widely diverse and included flavonoids, hydroxycinnamic acids, tyrosols, and lignans. Grosheimin and its derivative were the most abundant STLs in all artichoke cultivars. Among the examined cultivars, "Campagnano", "Grato 1", and "Violetto di Provenza" were found to be the richest in polyphenols and presented the highest antioxidant activity, whereas "Blanca de Tudela" and "Carderas" were characterized by a high STLs content. Hence, specific artichoke cultivars can be selected as the source of natural antioxidants with a desired profile of nutraceutical compounds like phenolics and STLs.

Degradation Kinetics and Mechanism of Lithospermic Acid under Low Oxygen Condition Using Quantitative 1H NMR with HPLC-MS

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.