Antiviral, haemolytic and molluscicidal activities of triterpenoid saponins from Maesa lanceolata:: Establishment of structure-activity relationships

Ten saponins isolated from the leaves of Maesa lanceolata were tested for their antiviral, haemolytic and molluscicidal activities. The influence of the substitution pattern of these acylated triterpenoid saponins on their biological activities was investigated and structure-activity relationships were established. Maesasaponin VI2 (3 beta -O-{[alpha -L-rhamnopyranosyl-(1 --> 2)-beta -D-galactopyranosyl-(1 -->3)]-[beta -D-galactopyranosyl-(1 --> 2)]-beta -D-glucopyranuronyl}-21 beta ,22 alpha -diangeloyloxy-13 beta ,28-epoxyolean-16 alpha ,28 alpha -diol), the most potent molluscicidal compound (LC50 0.5 ppm), also showed virucidal and haemolytic activity. In general, 21,22-diacylation appeared to be associated with a virucidal (reduction factor of the viral titer greater than or equal to 10(3) at 50 mug/ml) and haemolytic activity (HC50 less than or equal to1 mug/ml).