Ulcer-protecting effects of a flavonoid fraction from Bidens aurea. Role of endogenous prostaglandins and microvascular permeability.

This study was designed to determine the ulcer-protecting effects of a flavonoid fraction obtained from the flowers of Bidens aurea (Aiton) Sherff against gastric lesions induced by absolute ethanol. The possible involvement of gastric mucus secretion, endogenous prostaglandins (PGs) and mucosal microvascular permeability (MVP) in the protection mediated by the flowers of B. aurea were also determined. Flavonoid fraction pretreatment (250 mg/kg) 120 min before absolute ethanol was most effective in necrosis prevention. There was also a marked increase (p < 0.001) in hexosamine content. Intraperitoneal administration of indomethacin (IND) (10 mg/kg) partially inhibited gastric protection and the values of PGE(2) were significantly (p < 0.001 and p < 0.05) augmented. In addition, administration of 250 mg/kg of the extract reduced the elevated MVP induced by alcohol in rat gastric mucosa. These results demonstrate that the gastroprotective effects of B. aurea flowers could be partly explained through a complex prostaglandin-dependent mechanism involving stimulation of mucus glycoprotein content and reduction of MVP values.