Gastroprotective Activity of Polygonum chinense Aqueous Leaf Extract on Ethanol-Induced Hemorrhagic Mucosal Lesions in Rats

Abstract

Polygonum chinense is a Malaysian ethnic plant with various healing effects. This study was to determine preventive effect of aqueous leaf extract of P. chinense against ethanol-induced gastric mucosal injury in rats. Sprague Dawley rats were divided into seven groups. The normal and ulcer control groups were orally administered with distilled water. The reference group was orally administered with 20 mg/kg omeprazole. The experimental groups received the extracts 62.5, 125, 250, and 500 mg/kg, accordingly. After sixty minutes, distilled water and absolute ethanol were given (5 mL/kg) to the normal control and the others, respectively. In addition to histology, immunohistochemical and periodic acid schiff (PAS) stains, levels of lipid peroxidation, malondialdehyde (MDA), antioxidant enzymes, and superoxide dismutase (SOD) were measured. The ulcer group exhibited severe mucosal damages. The experimental groups significantly reduced gastric lesions and MDA levels and increased SOD level. Immunohistochemistry of the experimental groups showed upregulation and downregulation of Hsp70 and Bax proteins, respectively. PAS staining in these groups exhibited intense staining as compared to the ulcer group. Acute toxicity study revealed the nontoxic nature of the extract. Our data provide first evidence that P. chinense extract could significantly prevent gastric ulcer.

Figure 1

Macroscopic appearance of gastric mucosal lesions of the rats in different groups. (a) Rats in the normal control group showed intact gastric mucosa. (b) The ulcer control group (pretreated with 5 mL/kg absolute alcohol) showed severe injuries to the gastric mucosa (white arrow). Absolute ethanol imposed extensive hemorrhagic necrosis to gastric mucosa. (c) The reference group (omeprazole 20 mg/kg) showed milder injuries to the gastric mucosa (white arrow) compared with the ulcer control rats. (d) Rat pre-treated with P. chinense (62.50 mg/kg) showed moderate injuries on the gastric mucosa (white arrow). (e) Pre-treated with 125 mg/kg of P. chinense extract suppressed lesions to a mild-moderate condition (white arrow). (f) Mild injuries of the gastric mucosa were found in those rats pre-treated with 250 mg/kg of P. chinense extract. (g) Pre-treatment with 500 mg/kg of the extract protected injuries at a mild condition and flattened the gastric mucosa observed (black arrow).

Figure 2

Histology evaluation of gastric mucosal lesions of the rats in different groups (H&E staining 10x). (a) Rats in the normal control group showed intact gastric mucosa. (b) The ulcer control group (pre-treated with 5 mL/kg absolute alcohol) showed severe disruption on the epithelium. The necrotic lesions penetrated deeply into mucosa (white arrow). Also, extensive edema and leucocyte infiltration of submucosal layer were seen (black arrow). (c) The reference group (omeprazole 20 mg/kg) showed a mild disruption of the epithelium with edema and leucocyte infiltration of submucosal layer. (d) Rat pre-treated with P. chinense (62.50 mg/kg) showed a moderate disruption of epithelium with edema and leucocytes infiltration of submucosal layer. (e) Pre-treated with 125 mg/kg of P. chinense extract suppressed disruption of surface epithelium with edema and leucocyte infiltration of submucosal layer to a mild-moderate condition. (f) Mild disruption of the epithelium was found in those rats pre-treated with 250 mg/kg of P. chinense extract. (g) Pre-treatment with 500 mg/kg of the extract protected the epithelium from disruption at a mild condition along with a mild edema and leucocytes infiltration of the submucosal layer.

Figure 3

PAS staining evaluation of gastric mucosal lesions of the rats in different groups (PAS staining 20x): (a) the normal control group; (b) the ulcer control group; (c) the reference group (omeprazole 20 mg/kg); (d). rat pre-treated with P. chinense (62.50 mg/kg); (e) rat pre-treated with P. chinense (125 mg/kg); (f) rat pre-treated with P. chinense (250 mg/kg); (g) rat pre-treated with P. chinense (500 mg/kg).

Figure 4

Immunohistochemical evaluation of expression of Hsp70 protein appearance of gastric mucosal lesions of the rats in different groups (20x): (a) the normal control group; (b) the ulcer control group; (c) the reference group (omeprazole 20 mg/kg); (d). rat pre-treated with P. chinense (62.50 mg/kg); (e) rat pre-treated with P. chinense (125 mg/kg); (f) rat pre-treated with P. chinense (250 mg/kg); (g) rat pre-treated with P. chinense (500 mg/kg).

Figure 5

Immunohistochemical evaluation of expression of Bax protein appearance of gastric mucosal lesions of the rats in different groups (20x): (a) the normal control group; (b) the ulcer control group; (c) the reference group (omeprazole 20 mg/kg); (d) rat pre-treated with P. chinense (62.50 mg/kg); (e) rat pre-treated with P. chinense (125 mg/kg); (f) rat pre-treated with P. chinense (250 mg/kg); (g) rat pre-treated with P. chinense (500 mg/kg).