Effects of malonic, maleic, citric and caffeic acids on the motility of human sperm and penetration of cervical mucus.

The spermicidal effect of four organic acids (malonic, maleic, citric and caffeic acids) was evaluated by adding the acids to sperm, and by observing sperm survival and penetration following addition of these acids to human cervical mucus. Direct addition of 0.1% malonic, maleic and citric acid rendered the sperm immotile by a reduction of pH. In capillaries filled with cervical mucus, the incorporation of 0.01% maleic, malonic and citric acids was sufficient to reduce sperm penetration, and at 0.1%, penetration was completely abolished. Thus, malonic, and maleic and citric acids show promise as cervical or vaginal contraceptives. Caffeic acid was found to be unsuitable owing to its insolubility in aqueous media. Electron microscopy indicated that human sperm do not undergo the acrosome reaction while penetrating cervical mucus in vitro.