Cytotoxic activity of the crude venom from Odontomachus affinis ants is mediated by thiol oxidation and mitochondrial...

Animal toxins, including ant venoms, contain numerous compounds with potential biomedical and therapeutic applications. Ant venoms are mostly composed by peptides and proteins that might elicit inflammatory responses and cytotoxicity. The venom of Odontomachus affinis, a predatory ant species endemic to Brazil, is still poorly studied. Here, we evaluated the cytotoxic activity of the venom extracted from O. affinis glands and investigated the underlying mechanisms. Glands from 826 ants were dissected, followed by venom extraction and characterization by UV-vis and fluorescence spectroscopy and also by chromatography/mass spectroscopy. Cell viability was determined by MTT and trypan blue assays and the type of cell death by flow cytometry using annexin V-FITC/PI. Plasma membrane integrity was evaluated by LDH release. Mitochondrial bioenergetics were evaluated by the estimation of mitochondrial O₂ consumption and transmembrane potential. Also, protein thiol groups and reduced glutathione (GSH) were evaluated by spectroscopy. The crude extract of O. affinis exhibited a structured absorbance band in the UV region with maximal absorbance at 280 nm and a fluorescence emission band at 350-360 nm region. The chromatogram revealed at least 11 different molecules in its composition. Odontomachusaffinis venom exhibited a concentration-dependent cytotoxicity in hepatoma and leukemia tumor cells, which was also observed in normal blood cells. Also, venom had the ability to affect mitochondria, increasing O₂ consumption. The mechanistic investigation conducted in leukemia cells revealed that venom induced-cell death was accompanied by plasma membrane permeabilization and oxidation of protein thiol groups and glutathione, which was associated with the dissipation of mitochondrial potential. Thus, O. affinis crude venom exhibits cytotoxic activity by triggering of mitochondrial permeabilization, affecting mitochondrial bioenergetics and cellular redox state. This study contributes to the comprehension of the mechanisms of toxicity of O. affinis venom and also prospects its potential as a source for novel bioactive molecules.