Spermicidal activity of an antifungal saponin obtained from the tropical herb Mollugo pentaphylla.

The ethyl acetate fraction of Mollugo pentaphylla, a tropical herb, contains an antifungal saponin (mollugogenol-A). We report here the spermicidal effects of this saponin. Washed sperm (> 100 x 10(6) with > 50% motility) from normal volunteers were incubated with varying concentrations (0-300 micrograms/ml) of mollugogenol-A at 30 degrees C. Sperm motility, velocity and viability were assessed at 0, 30, 60 minutes both manually and by using computer assisted semen analysis (CASA). Samples collected at 0 and 60 minutes were evaluated for membrane lipid peroxidation, superoxide dismutase (SOD) activity and transmission electron microscopy. A dose- and time-dependent effect of this saponin on sperm motion and viability was observed. The maximal spermicidal effect (4-5 fold decrease in motility and viability) was observed with 300 micrograms/ml dose of saponin. A three-fold increase in sperm membrane lipid peroxidation with corresponding inhibition of SOD activity were observed after 60 minutes incubation with this spermicidal agent. Transmission electron microscopy of saponin-treated samples revealed significant damage to the sperm membrane in both head and tail regions, and the acrosomal membranes were notably swollen and disrupted. These results indicate that this natural saponin has a potential spermicidal effect besides its known antifungal activity. The likely mechanism of its action involves sperm membrane damage by increased lipid peroxidation.