n-Butanol extract of Rhynchosia volubilis Lour: A potent spermicidal agent In Vitro

Rhynchosia volubilis Lour has been a major drug in a folk prescription for contraception in China, whereas its mechanism remains unknown. Its antifertility effects on male mice and antimicrobial activities on sexually transmitted infection (STI) pathogens were previously reported. This study was undertaken to develop the n-Butanol extract of Rhynchosia volubilis Lour (BERVL) as a spermicidal agent with STI prevention. The spermicidal activities of BERVL with different doses were assessed using selected high-motile sperms of normal human semen samples, and their inhibitory effects on Lactobacillus acidophilus were determined. The mechanism of the spermicidal activity was explored by aqueous Eosin Y and Hoechst 33342/PI staining. The results showed spermicidal activities and inhibitory effects of BERVL on Lactobacillus acidophilus were dose-dependent. Dose of 90 mg/mL BERVL terminated all progressive sperm motility within 2 min, and had slight inhibitory effect on Lactobacillus acidophilus, suggesting it was an effective and safe dose for contraception use. About 80% sperms exposed to BERVL displayed changes consistent with high permeability of head membrane. It is concluded that BERVL as spermicide has advantages over N-9 with strong ability to instantaneously kill human sperm and possesses light inhibitory effect on Lactobacillus acidophilus.