Jia-Ping Ke,Jing-Ya Yu,Biao Gao,Feng-Lin Hu,Feng-Qing Xu,Guangmin Yao,Guan-Hu Bao
Green tea polyphenols show positive effects on human health and longevity. However, knowledge of the antiaging properties of green tea is limited to the major catechin epigallocatechin gallate (EGCG). The search for new ingredients in tea with strong antiaging activity deserves further study. Here we isolated and identified two new catechins from Zijuan green tea, named zijuanin E (1) and zijuanin F (2). Their structures were identified by extensive high-resolution mass spectroscopy (HR-MS), nuclear magnetic resonance (NMR), ultraviolet–vis (UV), infrared (IR) and circular dichroism (CD) spectroscopic analyses, and their 13C NMR and CD data were calculated. We used the nematode Caenorhabditis elegans (C. elegans) to analyze the health benefits and longevity effects of 1 and 2. Compounds 1 and 2 (100 μM) remarkably prolonged the lifespan of C. elegans by 67.2% and 56.0%, respectively, delaying the age-related decline of phenotypes, enhancing stress resistance, and reducing ROS and lipid accumulation. Furthermore, 1 and 2 did not affect the lifespan of daf-16, daf-2, sir-2.1, and skn-1 mutant worms, suggesting that they might work via the insulin/IGF and SKN-1/Nrf2 signaling pathways. Meanwhile, 1 and 2 also exhibited strong antioxidant activity in vitro. Surface plasmon resonance (SPR) evidence suggests that zijuanins E and F have strong human serum albumin (HSA) binding ability. Together, zijuanins E and F represent a new valuable class of tea components that promote healthspan and could be developed as potential dietary therapies against aging.
Zijuan tea is a new cultivar produced in Yunnan province of China. Unlike most tea cultivars, Zijuan tea is anthocyanin-rich. The composition and antioxidant activities of anthocyanins of Zijuan tea were studied for the first time in this paper. Anthocyanins were extracted with acidified methanol and quantified as 707 ± 28 μg/g of dry weight (cyanidin-3-O-β-d-glucoside equivalent) by high-performance liquid chromatography (HPLC) analysis. Four anthocyanins were successfully identified after Amberlite XAD-7HP adsorption column chromatography and octadecyl silane (ODS) flash chromatography. Among the four, delphinidin-3-O-β-d-galactoside (1) and cyanidin-3-O-β-d-galactoside (2) were confirmed by liquid chromatography–electrospray ionization mass spectrometry (LC-ESI-MS) and HPLC. Delphinidin-3-O-β-d-(6-(E)-p-coumaroyl) galactopyranoside (3) and cyanidin-3-O-β-d-(6-(E)-p-coumaroyl) galactopyranoside (4) were characterized by the high-resolution time-of-flight-mass spectrometry (HRTOF-MS) and nuclear magnetic resonance (NMR) spectrometry. The antioxidant activities of compounds 3 and 4, which composed approximately 75% of the total anthocyanins content in HPLC analysis, were evaluated by DPPH and FRAP assays. Results showed that both had higher antioxidant activities than commercial antioxidants butylated hydroxytoluene (BHT) used as one of controls in these assays.
Aroma volatiles from zijuan and pu-erh green teas were extracted by headspace solid-phase microextraction (HS-SPME). They were then characterized and identified using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The conditions of HS-SPME, including fiber selection and optimization of sampling conditions, have been previously investigated. Under optimal conditions, 51 and 42 aroma-active compounds were detected and characterized in zijuan and pu-erh green tea samples, respectively. Alcohols, ketones, and hydrocarbons were qualitatively the most dominant aroma-active compounds in zijuan and pu-erh green teas. The aroma-active compounds with similar sensory descriptors were grouped into the same category, and the sum of individual aroma intensity values within each category showed that the “floral” aroma, “woody” aroma, and “fruity” aroma in both zijuan and pu-erh green teas were the major aroma categories. These aroma notes were closely related to the characteristics of green tea aroma and its sensory perception.
危险品化学品经营许可证（带存储）