Obtaining valuable treatments for infection from our natural environment is well known, after all penicillin came from a fungus. This is an overview of a study to find fungicidal agents in scorpion venom.
Fungi capable of causing disease in plants, known as phytopathogenic fungi, are a cause of production loss and hence economic loss to the agricultural industry. In the search for suitable treatments for such diseases, scientists have examined numerous naturally occurring substances for any fungicidal activity.
A group of South American scientists based in Caracas, Venezuela and Rio de Janeiro, Brazil has examined the venom of the scorpion, Tityus discrepans, for fungicidal activity. The venom was purified though a column and the resulting fraction tested for activity against the black fungus Macrophomina phaseolina.
This soil borne fungus causes charcoal rot in over five hundred species of plant. Plants infected by M. phaseolina include soybean, peanut cabbage alfalfa and corn.
Of the toxin fractions obtained from the venom, seven were found to have some form of fungicidal activity. Of these, six were found to be peptides (chains of amino acids). The characterization of the seventh fraction is currently uncertain; it may be a peptide or some other form of organic molecule. The molecular mass of each fraction is known and they range from 1061.1 to 6823.3 Daltons.
Once the antifungal action of these fractions was observed, the scientists started to research the mode in which the toxins interacted with the fungus. They ascertained that they acted in three different ways. First, they decreased the activity of the fungal enzyme esterase. Secondly, they altered the membrane permeability to sodium ions. Finally, they altered the sterol biosynthesis within the cell walls of the fungus either by inhibiting ergosterol biosynthesis or by producing ergosterol analogues. All of the purified fractions could either abolish or inhibit fungal esterase activity and most combined this with one or both of the other actions.
The combination of the decreased esterase activity and increased leakage of sodium ions was sufficient to render samples of M. phaseolina unviable. While this study does not, as yet, provide a viable industrial source of a agricultural fungicide further, study of the toxins and their actions may prove of use in its development.
Scorpion Toxins Modify Phytopathogenic Fungus Physiology. A Possible Source of New Fungicides - Galax Joya, Gina D’Suze, Victor Salazar, Arnaldo Rosales, Carlos Sevcik, Gonzalo Visbal, Andre T. S. Ferreira, and Jonas Perales Journal of Agriculture and Food Chemistry, 2011, 59 (11), pp 6327–6337 DOI: 10.1021/jf200486t