Exploring novel thiazole-based minor groove binding agents as potential therapeutic agents against pathogenic Acanthamoeba castellanii

Due to limited advances in diagnosis and targeted therapy, as well as poor understanding of pathophysiology, infections due to Acanthamoeba have remained a medical concern. With their ability to selectively bind to DNA sequences, minor groove binders have emerged as useful therapeutic agents against parasitic infections. Herein, 6 novel thiazole-based minor groove binders were synthesized. Purification of intermediate compounds was accomplished by utilising silica gel column chromatography, while thin-layer chromatography was utilised to monitor reactions. The purification of the final products was achieved using liquid chromatography. Confirmation of structures was achieved by NMR spectroscopy and mass spectrometry. All compounds were evaluated against pathogenic A. castellanii via in vitro assays. At micromolar concentrations, selected minor groove binder derivatives revealed potent effects against (i) A. castellanii trophozoites as observed using amoebicidal assays, (ii), against A. castellanii cysts as observed using excystation assays, and (iii) against A. castellanii-mediated host cell death utilising human cerebrovascular endothelial cells, but (iv) showed limited effects against host cells alone, using cytotoxicity assays. The binding interaction between minor groove binders and DNA was studied using isothermal titration calorimetry and molecular docking simulations to provide insights into their binding affinity and mode of interaction. The findings of our study underscore the therapeutic value of thiazole-based minor groove binders as potent agents against A. castellanii, demonstrating effective antiamoebic activity with a low propensity for human cell damage, thus supporting their further development as antiamoebic agents.