Antiulcer activity of naturally occurring pyrano-coumarin and isocoumarins and their effect on prostanoid synthesis using human colonic mucosa.

Oral administration of bergenin and norbergenin, two isocoumarins, isolated from the leaves and roots of Flueggea microcarpa and luvangetin, a pyranocoumarin isolated from the seeds of Aegle marmelos Correa, showed significant protection against pylorus-ligated and aspirin-induced gastric ulcers in rats and cold restraint stress-induced gastric ulcers in rats and guinea pigs. The study on prostaglandins release by human colonic mucosal incubates, indicated a concentration-dependent (1-10 micrograms/ml) stimulatory effect of bergenin and norbergenin, while luvangetin (1-10 micrograms/ml) did not produce any effect. The results suggest that gastroprotective effects of bergenin and norbergenin could be due to increased prostaglandin production while, some other mucosal defensive factors may be involved for luvangetin.