Cyclodextrin enhances spermicidal effects of magainin-2-amide

Magainins are antimicrobial peptides with known spermicidal activity. Their activity is inhibited by cholesterol present in eukaryotic cell membranes. Pretreatment of spermatozoa with methyl-beta -cyclodextrin, which extracts cholesterol from cell membranes and induces capacitation, sensitizes them to magainin-2-amide as shown by a decrease in human sperm motility determin ed by computer-assisted sperm analysis and a concomitant decrease in sperm viability, as measured by MitoTracker(R) Red CMXRos labeling. Magainin-2-am ide affects mainly the fast progressive spermatozoa inducing them directly into an immotile state, without an increase in motile non-progressive and s low progressive spermatozoa. We conclude that methyl-beta -cyclodextrin hig hly potentiates the deleterious effect of magainin-2-amide on human spermat ozoa. Most probably, this effect can be explained by cholesterol extraction from sperm cell membranes. (C) 2000 Elsevier Science Inc. All rights reser ved.