Antifungal and molluscicidal saponins from Serjania salzmanniana

An investigation of Serjania salzmanniana for biologically active substances has led to the isolation of two novel saponins, salzmannianoside A (3-O-[[beta-D-glucopyranosyl-(1-->4)]-[(alpha-L- rhamnopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]gypsogenin [3] and salzmannianoside B (3-O-[[beta-D-glucopyranosyl- (1-->4)]-[alpha-L-arabinopyranosyl-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]hederagenin) (4). Two known saponins, pulsatilla saponin D (3-O-[[beta-D-glucopyranosyl-(1-->4)]-[alpha-L- rhamnopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]hederagenin) (1) and 3-O-[[beta-D-glucopyranosyl-(1-->4)]-[alpha-L-rhamnopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl]oleanolic acid (2) were also isolated from this plant. The structures of 3 and 4 were elucidated by FABMS and 2D NMR techniques. All these four saponins were mollusicidal, causing 70-100% mortality at 10 ppm against Biomphalaria alexandrina, a vector of Schistosoma mansoni in the Nile Valley. The saponins also showed antifungal activity against Cryptococcus neoformans and Candida albicans at minimal inhibitory concentrations of 8 and 16 mu g/mL, respectively.