Antiprotozoal Activity and Selectivity Index of Organic Salts of Albendazole and Mebendazole

Infections from the protozoa Entamoeba histolytica (E. histolytica), Giardia lamblia (G. lamblia), and Trichomonas vaginalis (T. vaginalis) pose a public health issue, with albendazole and mebendazole serving as the second-line medications for treating these parasitic infections. However, the low aqueous solubility of these compounds has led to the exploration of new strategies to enhance their solubility, with the formation of salts being a commonly employed strategy. The sulfonates A1, A2, and A3 of albendazole, along with M1, M2, and M3 of mebendazole, were synthesized. The antiparasitic activity in vitro was assessed against the trophozoites of E. histolytica, G. lamblia, and T. vaginalis. The salts A2, A3, M2, and M3 demonstrated a greater antiparasitic effect (IC50 37.95–125.53 µM) compared to the positive controls albendazole and mebendazole. The salts A1, A3, M2, and M3 do not exhibit cytotoxic effects at concentrations of 500 µM on the Vero cell line. Taken together, these findings indicate that the formation of these new solid saline phases enhances the antiparasitic effects in vitro, which is crucial in the current search for improved, safe, and effective antiparasitic agents.