Dermaseptins and magainins: antimicrobial peptides from frogs' skin-new sources for a promising spermicides microbicides-a mini review

Abstract

Sexually transmitted infections (STIs) and human immunodeficiency virus (HIV), the causative agents of acquired immunodeficiency syndrome (AIDS), are two great concerns in the reproductive health of women. Thus, the challenge is to find products with a double activity, on the one hand having antimicrobial/antiviral properties with a role in the reduction of STI, and on the other hand having spermicidal action to be used as a contraceptive. In the absence of an effective microbicide along with the disadvantages of the most commonly used spermicidal contraceptive worldwide, nonoxynol-9, new emphasis has been focused on the development of more potential intravaginal microbicidal agents. Topical microbicides spermicides would ideally provide a female-controlled method of self-protection against HIV as well as preventing pregnancies. Nonoxynol-9, the only recommended microbicide spermicide, damages cervicovaginal epithelium because of its membrane-disruptive properties. Clearly, there is an urgent need to identify new compounds with dual potential microbicidal properties; antimicrobial peptides should be candidates for such investigations. Dermaseptins and magainins are two classes of cationic, amphipathic alpha-helical peptides that have been identified in the skin extracts of frogs Phyllomedusa sauvagei and Xenopus laevis. Regarding their contraceptive activities and their effect against various STI-causing pathogens, we believe that these two peptides are appropriate candidates in the evaluation of newer and safer microbicides spermicides in the future.

Figure 1

Effect of dermaseptin on sperm motility. Motile spermatozoa were preincubated in the presence or absence of increasing concentrations of five dermaseptins derivatives for 20 seconds photomicrographics (a) control and (b) in the presence of dermaseptin; complete sperm immobilization was seen after treatment (aggregate of spermatozoa at EC₁₀₀ = 25 μg/mL)). Original magnification 100 [44].

Figure 2

Effect of spermicidal dermaseptins on sperm acrosome and flagellar plasma membrane integrity. Motile sperm were preincubated in the presence of spermicide solution (EC100 = 25 μg/mL) of K4S4 and was double labelled with Fluorescein Isothiocyanate-conjugated-Pisum sativum Agglutinin for acrosome labelling (FITC/green) and mouse antitubulin antibody for the flagellum staining (CY3/red). The sperm heads exhibited a “dotted” green fluorescence attesting for the presence of an acrosome. At the flagellar level, we observed a loss of membrane integrity since the anti tubulin antibodies have reached their axonemal microtubule target [44].