Encapsulated LyeTx III Peptide: Cytotoxic Agent Isolated from Spider Venom.

The discovery of novel cytotoxic drugs is of paramount importance in contemporary medical research, particularly in the search for treatments with fewer side effects and higher specificity. Antimicrobial peptides are an interesting class of molecules for this endeavor. In this context, the LyeTx III, a new peptide extracted from the venom of the spider, stands out. The peptide exhibits typical antimicrobial traits: a positive net charge and amphipathic α -helix structure in lipid-like environments. Its unique sequence (GKAMKAIAKFLGR-NH), identified via mass spectrometry and Edman degradation, shows limited similarity to existing peptides. Significantly, when liposome-encapsulated, LyeTx III demonstrates selective activity against tumor cells in culture. Our MTT results showed that the cytotoxicity of the peptide increased against HN13 cells when administered as liposomes, with their viability in HN13 cells alone being 98%, compared to 38% in liposome-encapsulated form. This finding underscores that the LyeTx III peptide may be a good candidate for the development of new drugs against cancer. Its activity when encapsulated is promising, as it can increase its half-life in the body and can also be targeted to specific tumors.