Role of the antioxidant properties in the gastroprotective and gastric healing activity promoted by Brazilian green propolis and the healing efficacy of Artepillin C

Green propolis is a resinous substance used in folk medicine given its anti-inflammatory, antibacterial, and anti-ulcer effects. Our research group has already confirmed the gastroprotective activity of hydroalcoholic extract from green propolis (HEGP), as well as of its main isolated compounds. In continuity, this study evaluated the antioxidant mode of action involved in the preventive effect induced by HEGP, and its therapeutic gastric healing potential on installed ulcers. In addition, the healing effect of its main compound Artepillin C was also investigated. Acute and chronic ulcers were induced in rats by given ethanol or acetic acid, respectively. In acute model, the rats were orally pre-treated with vehicle (water plus 1% Tween, 1 mL/kg), HEGP (30–300 mg/kg), or carbenoxolone (200 mg/kg) 1 h prior the ulcer induction. In the chronic ulcer protocol, the rats received vehicle (water plus 1% Tween, 1 mL/kg), HEGP (300 mg/kg), or omeprazole (20 mg/kg) twice a day by 7 days, whereas groups of mice received vehicle (water plus 1% Tween, 1 mL/kg), Artepillin C (18 mg/kg), or ranitidine (20 mg/kg) twice a day by 4 days. Ulcerated tissue was collected for histological, histochemical, immunostaining, oxidative, and inflammatory analyses. The in vitro scavenger activity of HEGP was also verified using the DPPH assay. The oral pre-treatment with HEGP (100 and 300 mg/kg) prevented the gastric epithelial damage promoted by ethanol. Besides, HEGP (100 and 300 mg/kg) reduced SOD activity about 11% and 26%, respectively, and increased the activity of GST around 20% and CAT in 80%. HEGP (300 mg/kg) also reduced the production of reactive oxygen species, as well as lipoperoxidation levels in the ethanol-ulcerated tissue. In the acetic acid-induced chronic ulcer, the daily treatment with HEGP (300 mg/kg) accelerates the healing process by 71%. In this model, HEGP normalized SOD and CAT activity and increased GST activity by 109% when compared to non-ulcerated rats. In both models, the extract administration increased the mucin PAS staining and reduced the myeloperoxidase activity at the ulcer site. Moreover, the treatment with HEGP enhanced the PCNA immunostaining, but did not alter the concentration of collagen in the acetic acid-ulcerated tissue. The extract had a direct DPPH radical-scavenging ability (LogIC 50 : 0.56). Besides, as expected, HPLC analysis showed Artepillin C as a major compound and its administration at 18 mg/kg also accelerated the gastric healin