Role of gastric mucus secretion, oxinitrergic system and sulfhydryl groups on the gastroprotection elicited by Polygala cyparissias (Polygalaceae) in mice.

Objectives This study has aimed to assess the mechanisms of action for the gastroprotective effect of the acetone extract (PCAE) and methanol fraction (PCMF) of Polygala cyparissias, as well as to evaluate the activity of 1,3,6,8-tetrahydroxy-2,7-dimethoxyxanthone (1), 1,7-dihydroxy-2,3-dimethoxyxanthone (2) and astragalin (3). Methods Gastric secretion and mucus content were determined by pylorus ligation in mice. Nitric oxide (NO) and sulfhydryl group participation were observed by the pretreatment of mice with L-NAME or NEM. Acute ulcer was induced by ethanol/HCl and chronic ulcer by acetic acid. Anti-Helicobacter pylori activity was evaluated by the agar solid dilution assay. Key findings Neither PCAE nor PCMF had the ability to reduce H+ concentration. However, both of them enhanced mucus secretion. PCAE demonstrated its gastroprotection in a NO-dependent manner, while PCMF exerted the activity depending on the sulfhydryl group. In chronic ulcer, the curative ratios for the PCAE and PCMF were 67.5 and 58.4%, respectively. No effect over H.pylori was detected. Compounds 1, 2 and 3 were able to reduce lesions in the order of 79.6, 73.8 and 67.6%, respectively. Conclusions The data suggested that PCAE and PCMF displayed antiulcer activity due to different mechanisms and with the participation of phenolic compounds obtained from the plant.