BACKGROUND Polyphenylene carboxymethylene sodium salt (PPCM) is a promising multipurpose technology for prevention of both sexually transmitted infections (STIs) and pregnancy. In preclinical studies, PPCM has demonstrated significant 1) antimicrobial activity against several important viral and bacterial pathogens and 2) contraceptive activity associated with premature acrosome loss (PAL). OBJECTIVE To further evaluate a vaginal antimicrobial compound as a contraceptive agent in preclinical studies utilizing a repurposed hyaluronan binding assay (HBA). MATERIALS AND METHODS Semen samples containing either neat semen or washed spermatozoa were treated with increasing concentrations of PPCM or calcium ionophore A23187 (positive control). Sperm inactivation was measured by two methods: 1) double acrosome staining (AS), and 2) a hyaluronan binding assay (HBA®). Percent inactivated sperm was compared between untreated control sperm and those treated with PPCM or A23187. RESULTS PPCM had a significant (P < 0.05) and dose-dependent effect on sperm inactivation in both assays, with HBA detecting a higher proportion of inactivated sperm than AS. PPCM did not affect sperm motility and exhibited equivalent responses in neat and washed samples. DISCUSSION Both HBA and AS confirmed that sperm were are rapidly inactivated at PPCM concentrations likely present in the vagina under actual use conditions and in a time-frame comparable to in vivo migration of sperm out of seminal plasma into cervical mucus. CONCLUSION PPCM vaginal gel may provide contraceptive protection as well as STI prevention. HBA may be a sensitive and much needed biomarker for sperm activity in future contraceptive development. This article is protected by copyright. All rights reserved.
Evaluation of the novel vaginal contraceptive agent PPCM in preclinical studies using sperm hyaluronan binding and acrosome status assays.