Anthelmintic effects of a cationic toxin from a South American rattlesnake venom

• Crotamine is toxic for Caenorhabditis elegans worms infected with Candida albicans and Candida krusei or not infected.
• Crotamine toxic effect on C. elegans worms is possibly due to disruption of acidic vesicles.
• C. elegans swallows and accumulates crotamine in its gastrointestinal tract as demonstrated by confocal microscopy.

Despite the unquestionable importance of the highly cationic feature of several small polypeptides with high content of positively charged amino acids for their biological activities, positively charged peptides do not necessarily have the capacity to cross the cell membranes. Interestingly, we found that crotamine, a positively charged amphiphilic peptide from the South American rattlesnake venom, has a unique cell-penetrating property with affinity for acidic vesicles, besides a well-characterized antimicrobial and antitumoral activities. In spite of a remarkable in vitro antifungal activity of crotamine against Candida spp., no significant effect of this peptide could be observed in the course of Candida albicans and Candida krusei infection on Caenorhabditis elegans asssed in vivo. These experiments, in which the nematode C. elegans was used as a living host, suggested, however, the potential anthelmintic activity of crotamine because of its uptake by the worms and accumulation in their acidic compartments. As described in the present work, this lysosomotropic property is consistent with a previously proposed mechanism of toxicity of crotamine on mammalian tumoral cell lines. This study also allowed us to propose the cationic peptides with lysosomotropic property, as crotamine, as a potential new class of anthelmentics with ability to overcome the challenging problems of drug resistance.

Accumulation of crotamine in the gastrointestinal tract of Caenorhabditis elegans suggesting oral swallowing as the main route of entrance of this toxin in worms. The anthelmintic activity seems to be dependent of the action of crotamine on acidic vesicles as demonstrated by acridine orange (AO) uptake and relocation. Schematic representation of hypothesized crotamine action on small acidic vesicles (with ∼pH 5) promoting the rupture of these vesicles and release of the AO dye into the cytoplasm observed by the significant increase of red and green fluorescence due to the increased pH (∼pH 7). The leakage of acidic endosomal/lysosomal vesicles is expected to ultimately underlie the cell death.Figure optionsDownload as PowerPoint slide