In vivo antioxidant and antiulcer activity of Parkia speciosa ethanolic leaf extract against ethanol-induced gastric ulcer in rats

Abstract

Background: The current study was carried out to examine the gastroprotective effects of Parkia speciosa against ethanol-induced gastric mucosa injury in rats.

Methodology/principal findings: Sprague Dawley rats were separated into 7 groups. Groups 1-2 were orally challenged with carboxymethylcellulose (CMC); group 3 received 20 mg/kg omeprazole and groups 4-7 received 50, 100, 200 and 400 mg/kg of ethanolic leaf extract, respectively. After 1 h, CMC or absolute ethanol was given orally to groups 2-7. The rats were sacrificed after 1 h. Then, the injuries to the gastric mucosa were estimated through assessment of the gastric wall mucus, the gross appearance of ulcer areas, histology, immunohistochemistry and enzymatic assays. Group 2 exhibited significant mucosal injuries, with reduced gastric wall mucus and severe damage to the gastric mucosa, whereas reductions in mucosal injury were observed for groups 4-7. Groups 3-7 demonstrated a reversal in the decrease in Periodic acid-Schiff (PAS) staining induced by ethanol. No symptoms of toxicity or death were observed during the acute toxicity tests.

Conclusion: Treatment with the extract led to the upregulation of heat-shock protein 70 (HSP70) and the downregulation of the pro-apoptotic protein BAX. Significant increases in the levels of the antioxidant defense enzymes glutathione (GSH) and superoxide dismutase (SOD) in the gastric mucosal homogenate were observed, whereas that of a lipid peroxidation marker (MDA) was significantly decreased. Significance was defined as p<0.05 compared to the ulcer control group (Group 2).

Figure 1. The effect of P. speciosa on the macroscopic appearance of the gastric mucosa in ethanol-induced gastric mucosal lesions in rats.

(G1) (Normal control group); (G2) (Ulcer control group); (G3) (Omeprazole); (G4) (50 mg/kg), (G5) (100 mg/kg), (G6) (200 mg/kg), (G7) (400 mg/kg) Parkia speciosa extract.

Figure 2. The effects of P. speciosa on SOD, MDA, GSH and GWM in the gastric mucosa homogenate of ethanol-induced gastric mucosal lesions in rats.

All values are expressed as the mean ± standard error of the mean. All P. speciosa-treated groups were significantly different from the control groups at p0.05. The data were analyzed by one-way ANOVA using the Statistical Package for the Social Sciences software (SPSS 18).

Figure 3. The effect of P. speciosa on the histology of ethanol-induced gastric mucosal damage in rats.

(G1) (Normal control group); (G2) (Ulcer control group); (G3) (Omeprazole); (G4) (50 mg/kg), (G5) (100 mg/kg), (G6) (200 mg/kg), (G7) (400 mg/kg) Parkia speciosa extract. The rats in groups 4–7 demonstrated comparatively better protection of the gastric mucosa, as shown by a reduction in or absence of the ulcer area, submucosal edema and leucocyte infiltration (H&E staining, 20×).

Figure 4. The effect of Parkia speciosa on gastric tissue glycoprotein-PAS staining in ethanol-induced gastric ulcers in rats.

(G1) (Normal control group); (G2) (Ulcer control group); (G3) (Omeprazole); (G4) (50 mg/kg), (G5) (100 mg/kg), (G6) (200 mg/kg), (G7) (400 mg/kg) Parkia speciosa extract (PAS stain 20×). Figure 4G1 is excluded from this article's CC BY license. See the accompanying retraction notice for more information.

Figure 5. Immunohistochemical analysis of HSP70 expression in the gastric mucosa of rats.

(G1) (Normal control group); (G2) (Ulcer control group); (G3) (Omeprazole); (G4) (50 mg/kg), (G5) (100 mg/kg), (G6) (200 mg/kg), (G7) (400 mg/kg) Parkia speciosa extract. HSP70 protein expression was upregulated in rats pretreated with Parkia speciosa (magnification 20×).

Figure 6. Immunohistochemical analysis of the expression of the BAX protein in the gastric mucosa of rats.

(G1) (Normal control group); (G2) (Ulcer control group); (G3) (Omeprazole); (G4) (50 mg/kg), (G5) (100 mg/kg), (G6) (200 mg/kg), (G7) (400 mg/kg) Parkia speciosa extract. BAX protein expression was downregulated in rats pretreated with Parkia speciosa (magnification 20×).