Potencial antimicrobiano e antiparasitário do veneno da Dinoponera quadriceps

Abstract

Animal toxins can be a source of molecular models for the design of new drugs. This study investigated the antimicrobial and trypanocidal potential from Dinoponera quadriceps ant venom (DqV) aiming to discover therapeutic value substances. We conducted the microdilution test, where it was determined the minimum inhibitory concentration (MIC) and Minimum Lethal Concentration (MLC) over Staphylococcus aureus ATCC 6538P , Escherichia coli ATCC 10536 , Pseudomonas aeruginosa ATCC 9027 , Salmonella subsp cholearaesuis choleraesuis serotype choleraesuis ATCC 10708 and Candida albicans ATCC 10231 strains and two microbial strains of Methicillin Resistant Staphylococcus aureus (MRSA), S. aureus ATCC 33591 and S. aureus CCBH 5330. MIC and MLC of DqV were respectively 6.25 µg/mL and 12.5 µg/mL for S. aureus ATCC 6538P, 3.12 µg/mL and 3.12 µg/mL for E. coli, 12.5 µg/mL and 12.5 µg/mL for P. aeruginosa, 12.5 µg/mL and 25 µg/mL for S. choleraesuis, 25 µg/mL and 50 µg/mL for C. albicans, 12.5 µg/mL and 50 µg/mL for S. aureus CCBH 5330 and 100 µg/mL and 100 µg/mL for S. aureus ATCC 33591. Mechanism of action experiments were performed for the strain of S. aureus ATCC 6538P methicillin-susceptible (MSSA), that changes in the permeability of the bacterial membrane of S. aureus treated with bacteriostatic and bactericidal concentrations of DqV was observed by the crystal violet assay and release of genetic material assay. A lowest MIC was observed when alkaline pH broth was used (7,5-9,0). Complete bacterial growth inhibition was observed after 4 h of incubation with the MLC of DqV. Bacterial morphology was analyzed by atomic force microscopy after exposure of bacteria to the CIM and CIM /2 of DqV for 4 hours, showing membrane damage. In antiparasitic assays, we determined the cytotoxic effects of the venom on epimastigote and trypomastigote forms of the Y strain of Trypanosoma cruzi. In epimastigotes, cytotoxicity was evaluated at 24 and 48 h, finding IC50 of 28.32 µg/mL and 20.67 µg/mL, respectively. The mechanism of cell death was assessed by flow cytometry and revealed the presence of necrotic and apoptotic involvement in the cytotoxic effect of DqV over epimastigote form, in addition, the appearance of double labeled cells with PI and Annexin V-FITC, indicating the occurrence of late apoptosis. Cytotoxicity was evaluated over trypomastigote finding an IC50 of 1.978 µg/mL and over RAW 264.7 cells finding an IC50 of 32.44 µg/mL. The venom showed antibacterial activity against S. aureus MSSA and MRSA, P. aeruginosa, S. choleraesuis, E. coli and C. albicans, suggesting membrane damage in S. aureus ATCC 6538P. Additionally, showed cytotoxic potential on epimastigote and tripomastigote forms of Y strain of T. cruzi.