Crystal violet structural analogues as candidates for drug repurposing in trypanosomatid diseases

CHANTAL REIGADA; NICKY DIDWANIA; MELISA SAYÉ; NAHID ALI; CLAUDIO A. PEREIRA

Rockville

Congreso; Molecular Parasitology Meeting XXXI; 2020

Genetics Society of America

Trypanosoma cruzi, the etiological agent of Chagas disease, has a metabolism largely based on the consumption of glucose and proline. Proline is also involved in differentiation processes, cellular invasion and resistance to different stresses. Up to date, the permease TcAAAP069 is the only proline transporter identified in T. cruzi and we have reported its importance on parasite survival. Interestingly, the AAAP transporters family is present in all trypanosomatid parasites and is low represented in mammals. Crystal violet (CV) was used for several years as a blood additive for prevention of transfusion transmitted Chagas disease. Recently, we have validated TcAAAP069 as one of the targets of CV and then we applied a virtual screening approach in order to identify drugs already approved in humans that might have similar effects to CV. The antihistamines loratadine (LTD) and cyproheptadine (CPH), and the antibiotic clofazimine (CFZ) were able to inhibit proline transport and had trypanocidal effect with IC50 values (the concentration that kills 50% of the parasites) between 1 and 13 µM in trypomastigotes and amastigotes. We also evaluated the in vitro antiprotozoal effect of these drugs in T. brucei and L. donovani, the causative agents of human African trypanosomiasis and visceral leishmaniasis, respectively. The CV structural analogues presented IC50 values between 1 and 31 µM in procyclic trypomastigotes of T. brucei. These compounds also had activity against L. donovani promastigotes with IC50 values between 2 and 44 µM. In addition, preliminary tests with cationic liposomal formulations of the drugs on this parasite showed that drug-loaded liposomes presented higher leishmanicidal activity than free compounds. Since proline permease TcAAAP069 has orthologous genes in Leishmania and T. brucei, LdAAP24 and TbAAT6, these compounds will be evaluated as inhibitors of the proline transport on both parasites as possible mechanism of action of such drugs. The strategy herein applied, based on the screening of approved compounds used to treat other pathologies, is known as drug repurposing. One of the main advantages of computer-aided drug repurposing is that reduces the time and the economic cost of implementation of new therapeutic alternatives, which is especially important in neglected diseases.