MOLLUSCICIDAL SAPONINS FROM A ZIMBABWEAN STRAIN OF PHYTOLACCA-DODECANDRA

Three new monodesmosidic saponins, all glycosides of 2 beta-hydroxyole anolic acid, were isolated from an aqueous extract of a Zimbabwean str ain of Phytolacca dodecandra. Their structures were, mainly by spectro scopic methods (LSIMS, H-1 NMR, COSY, NOESY, TOCSY, J-resolved (1)HNMR , (13)CNMR, HETCOR), established as -O-(beta-D-glucopyranosyl)-beta-D- glucopyranosyl]2 beta-hydroxyoleanolic acid, hamnopyranosyl-(1-->2)-O- [beta-D-galactopyranosyl- (1-->3)]-beta-D-glucopyranosyl} 2 beta-hydro xyoleanolic acid and O-(beta-D-galactopyranosyl)-beta-D-glucopyranosyl ] 2 beta-hydroxyoleanolic acid. Two of the saponins were submitted to a preliminary screening for molluscicidal activity against the schisto somiasis transmitting snail Biomphalaria glabrata and showed, respecti vely, strong and weak activity. In addition, four saponins previously reported from other strains of Phytolacca dodecandra were identified.