Avaliação de compostos polioxidoniobatos na inativação de Acanthamoeba.

Abstract

The amoebas from the genus Acanthamoeba are protozoa widely distributed in the environment. Despite free-living organisms, they can cause serious infections in humans. One of them is Acanthamoeba keratitis (CA), a disease that affects the cornea and has the contact lenses (CL) wearing as the main risk factor. Improper handling and incorrect hygiene habits with the lens contribute to contamination. Therefore, new approaches aiming effectively eliminate the protozoan are needed. Polyoxidoniobates are niobium-based compounds that inactivateSars-Cov-2 virus. These compounds are the basis for a commercial product used in surface disinfection. In this context, the objective of this work was to evaluate the biocidal effect of four polyoxidoniobates in the inactivation of Acanthamoeba trophozoites and cysts. The assays were performed with a strain of A. castellanii (ATCC #30010) cultivated axenically. The action of the compounds INNIB41® (200ppm), M (125ppm), M-Cu (125ppm) and M-CoE (125 ppm) was initially evaluated on trophozoites, for contact times of 15 minutes to 6 hours, by viability assessment by exclusion of 0.2% trypanblue.Only the compound M had a significant amoebicidal effect and then used in subsequent assays, as follows. (a) cytotoxicity for HEK-293 cells by determination of 50% cytotoxic concentration (CC50); (b) amoebicidal effect on trophozoites in a concentration-response assay and determination of 50% lethal concentration (LC50); (c) amoebistatic effect, by evaluating growth in a nutrient medium; (d) cysticidal effect, determining viability by a culture method, and (e) effect on the profile of secreted proteases, through a zymography assay. The CC50 for HEK-293 cells and the LC50 after 24 h of contact was 227.1 ppm and 288.1 ppm, respectively. Compound M at 225 ppm (concentration close to CC50 and below LC50) had an amoebistatic action, inhibiting the multiplication of trophozoites by 20% after 48h. Furthermore, it induced the formation of pre-cysts and cysts (8.3%) compared to the control. There was no cysticidal action of compound M at 225 ppm, however at 500 ppm the viability of the cysts decreased to 60% compared to the control. There was no effect on the profile of trophozoites secreted proteases, but samples treated with M at 225 ppm showed greater intensity of digestion areas. In conclusion, compound M has an action on Acanthamoeba trophozoites and cysts and has the potential to be a component of products for disinfecting and cleaning lenses. Additional studies could determine safe concentrations and the possible interactions and synergistic effects of polyoxidoniobate compounds with other amoebicides.