Exploring the protein profile and biological activity of Crotalus molossus venom against E. coli, P. aeruginosa and S. aureus bacteria and T47D breast carcinoma cells

Mexico has the highest diversity of snake species in the world, following Australia when considering just venomous snakes. Specifically, in Sonora, the second largest state in the country, more than 15 highly venomous species occur, including the northern black-tailed rattlesnake (Crotalus molossus). This specie's venom has not been as thoroughly researched in contrast with other Mexican vipers, nevertheless some studies report its biological activity and even pharmacological potential with antibacterial and cytotoxic activity. In this study we identified the main protein components from a pool of C. molossus venom through a gel-free proteomics approach, reporting ∼140 proteins belonging to the SVMP (38.76%), PLA₂ (28.75%), CTL (11.93%), SVSP (6.03%) and LAAO (5.67%) toxin families. To study its biological activities, we evaluated its hemolytic, antibacterial, and cytotoxic activity in red blood cells, Gram positive and negative bacteria and a luminal A breast carcinoma cell line (T47D), respectively, in vitro. We report that concentrations <100 μg/mL are potentially not hemolytic and reduced the bacteria viability of E. coli and S. aureus with an IC₅₀ of 10.27 and 11.51 μg/mL, respectively. Finally, we determined the C. molossus venom as cytotoxic against the T47D breast carcinoma cell line, with an IC₅₀ of 1.55 μg/mL. We suggest that the evaluated cytotoxicity was due to a high abundance of SVMPs and PLA₂s, since it's been reported that they affect the extracellular matrix and membrane permeation. This may provide a useful tool for pharmaceutical screening in the future.