Protective effects of tea extracts against alcoholic fatty liver disease in mice via modulating cytochrome P450 2E1 expression and ameliorating oxidative damage

Abstract

The alcoholic fatty liver disease (AFLD) has been a severe public health problem. Oxidative stress is involved in the initiation and progression of AFLD. Tea is a popular beverage worldwide with strong antioxidant activity. In this research, our purpose is to explore and compare the effects of 12 selected teas on AFLD. The ethanol liquid diet was used to feed the mice, and 12 tea extracts were administrated at 200 mg/kg body weight every day for 4 weeks. The results showed that the application of several tea extracts exhibited different inhibitory effects on lipid accumulation induced by sub-acute alcohol consumption based on the determination of triglyceride concentration and the histological alteration in the liver. In addition, several teas significantly decreased serum alanine aminotransferase and aspartate aminotransferase activities, inhibited the cytochrome P450 2E1 expression, and promoted alcohol metabolism (p < .05). Besides, compared with the model group, several teas obviously elevated superoxide dismutase and glutathione peroxidase activities as well as glutathione content, and remarkably decreased malondialdehyde level (p < .05). In general, Fried Green Tea, Fenghuang Narcissus Oolong Tea, and Pu-erh Dark Tea possessed potential preventive effects on AFLD. Moreover, the main phytochemicals in the three tea extracts were determined and quantified via high-performance liquid chromatography, and the most commonly detected ingredients were catechins and caffeine, which could exert the protective effects on AFLD.

Keywords: alcohol metabolism; alcoholic fatty liver disease; antioxidant activity; lipid accumulation; tea.

FIGURE 1

The animal experimental progress of the effect of tea extracts on AFLD. During the experimental period, the liquid diets were freshly prepared, and replaced at 6:00 o'clock (p.m.) every day. Moreover, the body weight of mice was weighed two times a week. The daily intake of liquid diets was recorded, and the feeding bottles were autoclaved (120°C, 30 min) every day

FIGURE 2

The effects of 12 teas on liver injury in mice with fatty liver induced by sub‐acute alcohol consumption. (a) AST, aspartate transaminase; (b) ALT, alanine aminotransferase. CTRL, the control group; EtOH, the model group; GT1, Selenium‐Enriched Enshi Yulu Tea; GT2, Fried Green Tea; YT1, Yuan'an Luyuan Tea; YT2, Mengding Huangya Tea; WT1, Gongmei White Tea; WT2, White Peony Tea; OT1, Wuyi Narcissus Tea; OT2, Fenghuang Narcissus Tea; BT1, Yihong Tea; BT2, Lapsang Souchong Tea; DT1, Qing Brick Tea; DT2, Pu‐erh Tea. *p < .05, the model group versus the control group; #p <.05, the tea extract treatment group versus the model group

FIGURE 3

The effects of 12 teas on lipid metabolism in mice with fatty liver induced by sub‐acute alcohol consumption. (a) Serum TG, serum triacylglycerol; (b) Serum TC, Serum total cholesterol; (c) Liver TG, Liver triacylglycerol; (d) Liver Coefficient. CTRL, the control group; EtOH, the model group; GT1, Selenium‐Enriched Enshi Yulu Tea; GT2, Fried Green Tea; YT1, Yuan'an Luyuan Tea; YT2, Mengding Huangya Tea; WT1, Gongmei White Tea; WT2, White Peony Tea; OT1, Wuyi Narcissus Tea; OT2, Fenghuang Narcissus Tea; BT1, Yihong Tea; BT2, Lapsang Souchong Tea; DT1, Qing Brick Tea; DT2, Pu‐erh Tea. *p < .05, the model group versus the control group; #p < .05, the tea extract treatment group versus the model group

FIGURE 4

The Morphological examination of hematoxylin and eosin (H&E) stained for all groups and Oil Red O staining for control and model groups (magnification: 200, scale bar: 100 μm; magnification: 400, scale bar: 50 μm). (a) CTRL, the control group; EtOH, the model group; (b) GT2, Fried Green Tea; OT2, Fenghuang Narcissus Tea; DT2, Pu‐erh Tea; GT1, Selenium‐Enriched Enshi Yulu Tea; BT1, Yihong Tea; BT2, Lapsang Souchong Tea

FIGURE 5

The effects of 12 teas on alcohol metabolism in mice with fatty liver induced by sub‐acute alcohol consumption. (a) CYP2E1, cytochrome P450 2E1; (b) ADH, alcohol dehydrogenase; (c) ALDH, aldehyde dehydrogenase. CTRL, the control group; EtOH, the model group; GT1, Selenium‐Enriched Enshi Yulu Tea; GT2, Fried Green Tea; YT1, Yuan'an Luyuan Tea; YT2, Mengding Huangya Tea; WT1, Gongmei White Tea; WT2, White Peony Tea; OT1, Wuyi Narcissus Tea; OT2, Fenghuang Narcissus Tea; BT1, Yihong Tea; BT2, Lapsang Souchong Tea; DT1, Qing Brick Tea; DT2, Pu‐erh Tea. *p < .05, the model group versus the control group; # p < .05, the tea extract treatment group versus the model group

FIGURE 6

The effects of 12 teas on antioxidant capacity and lipid peroxidation level in mice with fatty liver induced by chronic alcohol consumption. (a) SOD, superoxide dismutase; (b) CAT, catalase; (c) GSH‐Px, glutathione peroxidase; (d) GSH, glutathione; (e) MDA, malondialdehyde. CTRL, the control group; EtOH, the model group; GT1, Selenium‐Enriched Enshi Yulu Tea; GT2, Fried Green Tea; YT1, Yuan'an Luyuan Tea; YT2, Mengding Huangya Tea; WT1, Gongmei White Tea; WT2, White Peony Tea; OT1, Wuyi Narcissus Tea; OT2, Fenghuang Narcissus Tea; BT1, Yihong Tea; BT2, Lapsang Souchong Tea; DT1, Qing Brick Tea; DT2, Pu‐erh Tea. *p < .05, the model group versus the control group; #p < .05, the tea extract supplemented group versus the model group

FIGURE 7

The relationship among tea, ethanol metabolism, and alcoholic fatty liver. Some tea extracts could prevent the formation of alcoholic fatty liver by promoting ethanol metabolism, inhibiting the expression of CYP2E1, ameliorating oxidative stress, and reducing lipid peroxide. ADH, alcohol dehydrogenase; ALDH, acetaldehyde dehydrogenase; CYP2E1, cytochrome P450 2E1; ROS, reactive oxygen species

FIGURE 8

The HPLC chromatograms of the standard compounds (a), Fried Green Tea (b), Fenghuang Narcissus Oolong Tea (c), and Pu‐erh Dark Tea (d) under 254 nm. 1, gallic acid; 2, gallocatechin; 3, epigallocatechin; 4, catechin; 5, chlorogenic acid; 6, caffeine; 7, epigallocatechin gallate; 8, epicatechin; 9, gallocatechin gallate; 10, epicatechin gallate; 11, catechin gallate; 12, ellagic acid; 13, myricetin; 14, quercitrin; 15, astragalin; 16, quercetin; 17, theaflavin; 18, kaempferol