RESUMEN
Three new monodesmosidic saponins, all glycosides of 2 beta-hydroxyoleanolic acid, were isolated from an aqueous extract of a Zimbabwean strain of Phytolacca dodecandra. Their structures were, mainly by spectroscopic methods (LSIMS, 1H NMR, COSY, NOESY, TOCSY, J-resolved 1H NMR, 13C NMR, HETCOR), established as 3-O-[2',4'-di-O-(beta-D-glucopyranosyl)-beta-D-glucopyranosyl]2 beta-hydroxyoleanolic acid, 3-O-[O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-galactopyranosyl- (1-->3)]-beta-D-glucopyranosyl]2 beta-hydroxyoleanolic acid and 3-O-[3'-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 schistosomiasis transmitting snail Biomphalaria glabrata and showed, respectively, strong and weak activity. In addition, four saponins previously reported from other strains of Phytolacca dodecandra were identified.
Asunto(s)
Moluscocidas/aislamiento & purificación , Plantas/química , Saponinas/aislamiento & purificación , Animales , Biomphalaria , Secuencia de Carbohidratos , Bovinos , Proteínas Hemolisinas/aislamiento & purificación , Técnicas In Vitro , Espectroscopía de Resonancia Magnética , Datos de Secuencia Molecular , Estructura Molecular , ZimbabweRESUMEN
The molluscicidal principles of Ethulia conyzoides were identified as ethuliacoumarin A (1) and isoethuliacoumarin A (2). Ethuliacoumarin A possessed an LC90 between 19 and 23.5 ppm depending on the age of the snail against Biomphalaria glabrata, and between 12 and 15 ppm against Bulinus truncatus. In addition, ethuliacoumarin A was found to be cercaricidal at 25 ppm and ovicidal. Ethuliacoumarin has the structural requirements considered essential for anticoagulant activity. Consequently the anticoagulant dicumarol (4) was tested and found to be molluscicidal in the range from 2.5 to 10 ppm. In contrast, the coumarin anticoagulant warfarin (3) did not show molluscicidal activity.