Antiulcerogenic and anti-inflammatory effects of emodin, isolated from Rhamnus triquerta wall.

Emodin, an anthraquinone derivative, isolated from the whole plant of R. triquerta, in 15 mg/kg dose (ip) exhibited anti-inflammatory activity against carrageenin-induced pedal inflammation in rats. In the same dosage it also showed antiulcer activity against 4 hr pylorus-ligated, aspirin and immobilization stress-induced gastric ulcers in rats. It decreased acid and pepsin output and augmented mucus secretion in terms of total carbohydrate: protein ratio in the gastric juice of aspirin treated pylorus-ligated rats, indicating that the antiulcerogenic effect of emodin may be due to its effect on gastric secretion.

Bioflavonoids and vasoactive mediator release from mast cells.

5-hydroxy and 7-hydroxy flavones significantly attenuated the carrageenin-induced pedal inflammation in rats; however, the anti-inflammatory effect declined at higher doses. These compounds produced positive inotropic effect on frog atria, which exhibited tachyphylaxis and was selectively abolished by indomethacin pretreatment. Studies on the rat mesenteric mast cells revealed that both the compounds, administered either in vitro or in vivo, induced a significant degree of mast cell degranulation in higher concentrations/doses. The mast cell degranulation induced by compound 48/80 was, however, prevented by lower, but not higher, concentrations/doses of the flavones. Local injection of 7-hydroxy flavone into the hind paw of rat showed that, in higher doses, the compound produced significant oedema. It was concluded that these compounds have a biphasic action: mast cell stabilisation and degranulation at lower and higher concentrations/doses, respectively.