TERPENOIDS ISOLATED FROM PSIDIUM-GUAJAVA HEXANE EXTRACT WITH DEPRESSANT ACTIVITY ON CENTRAL-NERVOUS-SYSTEM

A bioguided fractionation of the hexane extract obtained from Psidium guajava leaves led to the isolation of sesquiterpenes with depressant activities on the central nervous system. The results demonstrated tha t the already reported relaxant properties of Psidium guajava hexane e xtract are largely due to the presence of terpenes, especially caryoph yllene-oxide and beta-selinene, which were by far the largest single c omponents and potentiated pentobarbital sleeping time and the latency of convulsions induced by leptazol in mice. Calcium concentration-resp onse curves showed a rightward displacement vc;hen the active fraction was added to isolated guinea-pig ileum depolarized with K+ (60 mM) an d cumulative concentrations of CaCl2, suggesting that caryophyllene-ox ide, a known Ca2+ antagonist agent could be responsible for the blocka de of extracellular Ca2+ observed with the active fraction.