Antioxidant-mediated preventative effect of Dragon-pearl tea crude polyphenol extract on reserpine-induced gastric ulcers.

Dragon-pearl tea is a type of green tea commonly consumed in Southwest China. In the present study, the antioxidative and anti-gastric ulcer effects of Dragon-pearl tea crude polyphenols (DTCP) were determined in vitro and in vivo. Treatment with 25, 50 or 100 µg/ml DTCP resulted in notable antioxidant effects in vitro, which manifested as 2,2-diphenyl-1-picrylhydrazyl and OH radical-scavenging activity. Furthermore, using an in vivo mouse model, DTCP was shown to reduce the gastric ulcer area in the stomach, in which the 200 mg/kg DTCP dose exhibited the most marked effect, with a gastric ulcer index inhibitory rate of 72.63%. In addition, DTCP was demonstrated to improve stomach acidity conditions in vivo by increasing the pH and reducing the level of gastric juice, as compared with the reserpine-induced gastric ulcer control mice. Furthermore, DTCP altered the serum levels of a number of oxidation-related biomolecules, including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), lipid peroxidation (LPO) and catalase (CAT), to subsequently exert an anti-gastric ulcer effect. Treatment with 50, 100 and 200 mg/kg DTCP increased the SOD, GSH-Px and CAT levels and reduced the MDA and LPO levels in the mouse model of gastric ulcers. These serum level alterations resulted in the modified serum levels of prostaglandin E2 (PGE2) and nitric oxide (NO), which are associated with gastric mucosal protection. A reverse transcription-quantitative polymerase chain reaction (RT-PCR) assay is a molecular biology experiment which could determine the changes of mRNA in tissues. Using the RT-PCR assay, DTCP was observed to increase the mRNA expression levels of certain genes associated with gastric ulcers: Epidermal growth factor, epidermal growth factor receptor, vascular endothelial growth factor and vascular endothelial growth factor receptor 1, while reducing gastrin expression levels. Therefore, the results indicated that DTCP induced a marked preventative effect on reserpine-induced gastric ulcers in vivo, as a result of its antioxidative capacity.