INHIBITION OF GASTRIC-ACID SECRETION BY THE AQUEOUS EXTRACT AND PURIFIED EXTRACTS OF STACHYTARPHETA-CAYENNENSIS

Stachytarpheta cayennensis Schauer (Verbenaceae) is used in folk medic ine to treat gastric and intestinal disturbances. The freeze-dried aqu eous extract of the whole plant tested to rodents up to the dose of 2 g kg(-1), p.o., did not produce signs of toxicity. The extract (0.5-2 g kg(-1), p.o.) increased the intestinal motility and protected mice a gainst ulcers induced by restraint-in-cold, ethanol or indomethacin. I njected into the duodenal lumen the extract inhibited the basal acid s ecretion as well as that induced by histamine and bethanecol in pyloru s-ligated mice. Partition of the aqueous extract in organic solvents y ielded semipurified fractions whose antiacid activity guided further c hemical purification. All the fractions were chromatographically chara cterized, the main substances in the active extract being flavonoids a nd amines; some substances were revealed only under UV light. The most purified active fraction obtained presented a specific activity 5-10 times higher than that detected in the original extract. Data from pha rmacological studies indicate that the antiulcer activity of S. cayenn ensis is related to a specific inhibition of gastric acid secretion. C holinergic and histaminergic stimulation of acid secretion were simila rly reduced by the extracts suggesting inhibition of common steps in b oth pathways, possibly at the level of histamine release/H-2 receptor interaction, or at the proton pump. Whatever the mechanisms involved, the present data confirm the plant effectiveness as antiacid/antiulcer and laxative.