Abstract
ABSTRACT: Tea polyphenols are known to prevent various ailments like cancer, atherosclerosis, hypertension and diabetes. Our study aimed at to decipher the gastroprotective effect of aqueous black tea extract (BTE) against ethanol-induced gastric damage and the role of BTE in modulating MMP-9 activity and expression, both in vivo and in vitro. The protective role of BTE was assessed in Sprague-Dawley rats after inducing damage with 70% ethanol. Human gastric adenocarcinoma cells (AGS) were treated with ethanol in ex vivo experiment. MMP-9 activity and expression were investigated through gelatin zymography and western blotting. Reactive oxygen species (ROS) generation was also studied by fluorescence spectroscopy and confocal microscopy, with or without treatment of BTE both in vivo and in vitro experiments. In addition, the effect of citric acid treated BTE (cBTE), which mimics lemon tea, was examined on ethanol-induced gastropathy. BTE exhibited antiulcer activity through reduction of glutathione depletion, lipid peroxidation, protein oxidation, ROS production and inflammatory cell infiltration in rat gastric tissues. In addition, BTE significantly inhibited synthesis and secretion of proMMP-9 both in vivo and in vitro. The mitochondrial enzymes succinate dehydrogenase and NADH oxidase in rat gastric tissues were downregulated by BTE while protecting gastric ulcer. Citric acid addition to BTE was observer to enrich the lead compound, catechin. Interestingly, cBTE showed higher anti-ulcer activity than the untreated one. BTE shows protective role against ethanol-induced gastric ulcer in rats through scavenging ROS and downregulating proMMP-9 activity. While cBTE shows better protection due to enrichment of catechin and removal of tannins in tea extract leading to enhanced inhibitory role on proMMP-9 activity and ROS production.