Scorpion Venom Unfriendly To Fungi

Scorpion toxins may be a new source of potential fungicides, researchers in Brazil and Venezuela report (J. Agric. Food Chem., DOI: 10.1021/jf200486t). The venom that scorpions inject into their victims contains a soup of peptides that wreak havoc on cell membranes. Scientists have noted that scorpions often spray themselves with their own venom to rid themselves of opportunistic fungal infections. But although over 500 compounds in two different scorpion species have been identified, their antifungal properties haven’t been tested. So, Gina D’Suze and Galax Joya at Instituto Venezolano de Investigaciones Científicas in Caracas, Venezuela, and colleagues investigated, thinking the compounds could be useful for the agrochemical industry, since fungal infections cause 35% of crop loss worldwide. The group selected seven molecules, six of them peptides, from the common South American scorpion Tityus discrepans. They exposed fungus Macrophomina phaseolina, which attacks bean plants, to the compounds, and all of them showed antifungal activity. The authors posit three possible mechanisms by which the molecules attack fungi: by inhibiting fungal esterases, affecting sodium membrane permeability, and inhibiting ergosterol synthesis.