Safe and effective vaginal contraceptives are urgently needed. Ideally, such products should have antimicrobial and antiviral properties; as such, they could also play a role in the reduction of sexually transmitted diseases (STDs), particularly the human immunodeficiency virus (HIV).
Most of the spermicidal products being marketed presently contain a detergent as an active ingredient, which do not provide any protection against STDs and that their effect in preventing HIV transmission remains controversial. Also, the repeated use of a surfactant as a vaginal contraceptive/microbicide has been associated with an increased risk of vaginal or cervical infection and irritation or ulceration. Because of this, it is important to identify and evaluate a new generation of contraceptive antimicrobial agents can be used vaginally in effective doses without causing overt vaginal irritation or other toxicity.
Antimicrobial peptides are produced by both prokaryotic and eukaryotic cells and have been the subject of many studies in recent years because of their involvement in host defense mechanisms and their potential use as therapeutic agents. These antimicrobial peptides include dermaseptins (DSs), a family of five structurally and functionally related peptides that were originally isolated from the skin of a tree-dwelling South American frog (Phyllomedusa sauvagei).
Recently, researchers from the Laboratory of Biochemistry, Faculty of Medicine, Sousse, Tunisia, thought that it would be interesting to develop a vaginal contraceptive with these compounds that have many biologic properties.
In their study, to be published in Contraception (available online 26 August 2005), the researchers set out to determine the effectiveness of two synthetic antimicrobial peptides, dermaseptin (DS1 and DS4) for inhibiting sperm motility. In addition, the mechanism of their spermicidal action was investigated and possible synergistic spermicidal effects exerted by EDTA were evaluated.
For the study, twenty samples of fresh semen were obtained from patients aged between 23 and 35 years. The data showed that sperm motility was inhibited with various concentrations of DS at different intervals ranging from 2 to 240 min. The action of DSs on sperm motility was observed to be dose dependent. Supplementation with pentoxifylline and that with calcium are known to enhance the motility of sperm but they did not prevent the spermicidal action of DSs.
This study indicates that DS is an effective agent to kill sperm. In view of this fact, it is suggested that DS4 has antibacterial, antiviral, antifungal and potentially spermicidal activities and could be a potent vaginal contraceptive.
However, the authors state that further studies are necessary to elucidate the mode of DS action, and suggest that considering the available information about contraceptive efficacy, the different biologic properties of these peptides should be studied as new candidates for human use as a barrier contraceptive agent with additional protection against STDs.