Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis, and Giardia intestinalis infections

Introduction: Toxoplasma gondii, Trichomonas vaginalis, and Giardia intestinalis are the causative agents of toxoplasmosis, trichomoniasis, and giardiasis, three important infections threatening human health and affecting millions of people worldwide. Although drugs and treatment are available to fight these protozoan parasites, side effects and increasing drug resistance require continuous efforts for the development of novel effective drugs. Areas covered: The patents search was carried out in September/October 2022 with four official scientific databases (Espacenet, Scifinder, Reaxys, Google Patents). Treatments for toxoplasmosis, trichomoniasis, and giardiasis (2015-2022) have been grouped according to their chemotypes. In particular, novel chemical entities have been reported and investigated for their structure-activity relationship, when accessible. On the other hand, drug repurposing, extensively exploited to obtain novel antiprotozoal treatment, has been in-depth described. Finally, natural metabolites and extracts have also been reported. Expert opinion: T. gondii, T. vaginalis, and G. intestinalis are protozoan infections usually controlled by immune system in immunocompetent patients; however, they could represent a threatening health for immunocompromised people. The needs of novel effective drugs, endowed with new mechanisms of actions, arises from the increasing drug resistance affecting antibiotic as well as antiprotozoal therapies. In this review different therapeutic approaches to treat protozoan infections have been reported.