Hung Wei-Lun, Yang Guliang, Wang Yu-Chuan, Chiou Yi-Shiou, Tung Yen-Chen, Yang Meei-Ju, Wang Bi-Ni, Ho Chi-Tang, Wang Yu, Pan Min-Hsiung
Citrus Research and Education Center, Department of Food Science and Human Nutrition, University of Florida, Lake Alfred, 33850, USA.
Food Funct. 2017 Sep 20;8(9):3276-3287. doi: 10.1039/c7fo00700k.
Theasinensins have been identified as a major group of unique catechin dimers mainly found in oolong tea and black tea. Among several types of theasinensins, theasinensin A (TSA), an epigallocatechin gallate (EGCG) dimer with an R-biphenyl bond, is the most abundant theasinensin prevalent in oolong tea. Previous studies have reported that TSA exhibits antioxidative, anti-inflammatory and anti-cancer activities in vitro and in vivo. However, little is known about the hepatoprotective effect of TSA. Thus, the aim of this study was to investigate the inhibitory effect of TSA on carbon tetrachloride (CCl)-induced hepatic fibrosis in mice. After intraperitoneal injection of CCl for eight weeks, histological lesions in the liver tissue and elevated serum levels of alanine aminotransferase and alkaline phosphatase were found in mice. Conversely, oral administration of TSA relieved CCl-induced liver injury as well as ameliorated liver functions. Our immunohistochemical staining results revealed that collagen deposition was profoundly reduced due to supplementation with TSA. In addition, we also found that hepatic α-smooth muscle actin (α-SMA) and matrix metallopeptidase 9 (MMP-9) expression was suppressed through the inhibition of transforming growth factor β (TGF-β). Taken together, our current findings suggest that TSA may serve as a potent bioactive constituent from oolong tea that acts against liver fibrosis through the inhibition of hepatic stellate cell (HSC) activation.
茶黄素已被确认为一类主要存在于乌龙茶和红茶中的独特儿茶素二聚体。在几种类型的茶黄素中，茶黄素A（TSA）是一种具有R-联苯键的表没食子儿茶素没食子酸酯（EGCG）二聚体，是乌龙茶中含量最丰富的茶黄素。先前的研究报道，TSA在体外和体内均表现出抗氧化、抗炎和抗癌活性。然而，关于TSA的肝保护作用知之甚少。因此，本研究的目的是探讨TSA对四氯化碳（CCl）诱导的小鼠肝纤维化的抑制作用。连续八周腹腔注射CCl后，小鼠肝脏组织出现组织学损伤，血清丙氨酸转氨酶和碱性磷酸酶水平升高。相反，口服TSA可减轻CCl诱导的肝损伤并改善肝功能。我们的免疫组织化学染色结果显示，补充TSA可显著减少胶原蛋白沉积。此外，我们还发现，通过抑制转化生长因子β（TGF-β），肝α平滑肌肌动蛋白（α-SMA）和基质金属肽酶9（MMP-9）的表达受到抑制。综上所述，我们目前的研究结果表明，TSA可能是一种来自乌龙茶的有效生物活性成分，通过抑制肝星状细胞（HSC）活化来对抗肝纤维化。
