Synthesis and antiulcer activity of uvaol hemiphthalate derivatives.

Disodium salts of the dihemiphthalates of urs-12-ene-3 beta, 28-diol 3b and of ursa-9(11), 12-diene-3 beta,28-diol 4b were synthesized from uvaol and examined for their gastroprotective activity in rats. The effects showed by 3b and 4b, given p.o. in two antiulcer tests (ethanol induced gastric lesions and diclofenac induced gastric ulcers), were 5-25 times better than those of carbenoxolone. When given p.o. in the rat once a day for 5 days at a gastroprotective dose, 3b and 4b did not induce any change in urine excretion, whereas carbenoxolone significantly reduced urine volume, Na+ excretion and Na+/K+ ratio. In conclusion, 3b and 4b are effective antiulcer agents, devoid of mineral-corticoid activity and therefore provided with a good therapeutic index.