Evaluation of in Vitro Bio-Activities Effects of WST (Wushanshencha)

Abstract

As a traditional Chinese drink, tea is favored for its rich flavor and its medicinal functionality. In this study, the in vitro bioactivities of Wushanshencha (WST; a local tea from Chongqing, China), which is processed mainly from the leaves of the wild Malus hupehensis (Pamp.) Rehd.). We assessed the scavenging capacity of tea extracts on 1, 1-diphenyl-2-picrylhydrazyl (DPPH); 2, 2′-azino-bis (3-ethylbenzthiazoline-6- sulphonic acid) diammonium salt (ABTS); and hydroxyl (OH) free radicals, and demonstrate the high antioxidant activity and dose-dependent relationship of these extracts. We also detail the anti-mutagenic effect of these tea extracts against the Salmonella typhimurium TA98 strain induced by the 2, 7-diaminofluorene (2, 7-AF) mutagen and the TA100 strain induced by the N-methyl-N′-nitro- N- nitrosoguanidine (MNNG) mutagen at concentrations of 1.25 and 2.50 mg/plate, respectively, with the high-dose groups showing better results. We investigated the anticancer mechanisms of WST extracts (40, 100, and 160 μg/mL) in HepG2 human hepatoma cells via 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay and quantitative real-time reverse transcription-polymerase chain reaction (RT-qPCR). The results showed that the proliferation of HepG2 cells was significantly inhibited in a dose-dependent manner by the tea extracts. Moreover, apoptosis in HepG2 cells was induced via upregulation of Caspase-3, Caspase-7, Caspase-8, Caspase-9, p21, p53, and Bax as well as downregulation of Bcl-2 apoptosis-associated factors, as assessed via mRNA expression levels after treating with WST extracts. The expression of inflammation-related factors, e.g., NF-κB, and Cox-2, was significantly downregulated by the WST extracts, demonstrating its inflammatory properties. Together, these observations indicated that WST extracts have anti-inflammatory and anti-cancer properties. In addition, high-performance liquid chromatography (HPLC) analysis showed that WST extracts contained chlorogenic acid, 4-hydroxycinnamic acid, isoquercitrin, taxifolin, quercitrin, rosmarinic acid, myricetin, baicalin, neosperidin dihydrochalcone, and quercetin. As such, WST appears to be an effectively functional drink, due to its rich functional components and anti-cancer activity.