Chemical profiling, quantitation, and bioactivities of Du-Zhong tea.

Du-Zhong tea is a health beverage produced from Eucommia ulmoides leaves (EUL) as raw materials using traditional tea processing and Chinese herbal pieces processing methods. To evaluate the differences between tender leaves and mature leaves of Du-Zhong tea, UPLC-Q-TOF MS was used to analyze the constituents in EUL collected in April and August. A total of 52 compounds, including iridoids, phenylpropanoids, flavonoids, lignans, and other types of compounds were identified. The contents of nine ingredients in the tender and mature leaves of E. ulmoides were determined by HPLC-DAD analysis. The results show that the average contents of the compounds in tender leaves were significantly higher than those in mature leaves. Lastly, the antioxidant and antipancreatic lipase activities of commercial Du-Zhong tea made by leaves of different maturity were evaluated. Du-Zhong tea with d-grade exhibited relatively higher antioxidant, while C-grade exhibited greater lipase inhibitory activities.

Study on enhanced extraction and seasonal variation of secondary metabolites in Eucommia ulmoides leaves using deep eutectic solvents.

It has been considered as a crucial field for the extraction of active ingredients from herbal medicine to use a green and efficient method in the medicinal and food industries. In recent years, deep eutectic solvents (DESs) have been obtaining increase attention in green chemistry area since its sustainability, safety and biodegradability. In this study, an efficient DES composed of choline chloride and L-(+)-ascorbic acid with a molar ratio of 2:1 performed higher efficacy on the extraction of target compounds (including iridoids, phenolic acids and flavonoids) in Eucommia ulmoides leaves than 50% methanol solution. Considering the extraction efficacy and time consumption, microwave-assisted extraction (MAE) was selected and the operational conditions, including power of microwave, liquid/solid ratio and irradiation time were optimized by response surface methodology (RSM). Water was used as anti-solvent to recover ten target analytes from DES with recovery yields of 97.59%, 94.91%, 96.09%, 90.66%, 95.16%, 87.33%, 86.57%, 82.15%, 89.28% and 80.75% for eucommiol (EU), aucubin (AU), geniposidic acid (GA), chlorogenic acid (CA), asperuloside (AP), rutin (RU), kaempferol-3-O-sambubioside (KS), isoquercitrin (IQ), kaempferol-3-O-rutinoside (KR) and astragaline (AS), respectively. By combining the DES-based MAE and quantitative analysis of multi-components by single mark (QAMS) methods, the contents of ten compounds in the leaves of Eucommia ulmoides were determined to clarify the relationship between the accumulation of secondary metabolites and the harvest period. It was found that the contents of main ingredients reached the highest during May to October. The period appears to be the best harvest period for Eucommia ulmoides leaves. This study provides a novel strategy for the harvesting, processing, and quality control of the raw materials from Eucommia ulmoides leaves.