Crystal violet structural analogues identified by in silico drug repositioning inhibit proline transporter TcAAAP069 and present anti Trypanosoma cruzi activity

SAYE M; GAUNA L; VALERA-VERA E; REIGADA C; MIRANDA MR; PEREIRA CA

Conferencia; DRUG DISCOVERY FOR NEGLECTED DISEASES INTERNATIONAL CONGRESS 2018. 4th Scientific Meeting of the Research Network.; 2018

Trypanosoma cruzi, the etiological agent of Chagas disease, has a metabolism largely based on the consumption of glucose and amino acids. Among them, proline is also involved in differentiation processes, cellular invasion and resistance to oxidative, nutritional and osmotic stress. We have previously identified the proline permease TcAAAP069 in T. cruzi demonstrating the importance of this transporter on parasite survival using a synthetic proline analogue that inhibits proline transporter and also has trypanocidal action. Crystal violet (CV) was used for several years in blood banks as an additive for prevention of transfusion-transmitted Chagas disease. One mechanism of action described for CV involves inhibition of proline and methionine uptake. Since current treatments for Chagas disease present several side effects and are only effective in the acute phase of the illness, there is an urgent need for new alternative therapies development. The aim of this work was to reposition drugs as inhibitors of TcAAAP069 with trypanocidal activity to treat Chagas disease using CV as reference molecule in a virtual screening protocol. In order to do that, we first validate CV as a TcAAAP069 inhibitor using wild-type parasites (TcWT) and parasites that overexpress the proline permease (Tc069). The transgenic Tc069 parasites were 2.5-fold more resistant to inhibition of proline uptake by CV than TcWT parasites. Also, Tc069 parasites were 47-fold more sensitive to CV trypanocidal action than TcWT parasites. A similarity-based virtual screening using CV as reference and a database that contains alreadyapproved drugs for clinical use led to the in silico identification of four compounds: olanzapine (OLZ, an antipsychotic), clofazimine (CFZ, an antibiotic), loratadine and cyproheptadine (LTD and CPH, both antihistamines). All of them inhibited TcAAAP069 activity with different efficacies and also presented trypanocidal action both in epimastigotes and trypomastigotes of the Y strain. Additionally, LTD, CPH and CFZ presented trypanocidal effect on epimastigotes of the CL Brener and DM28c strains. Finally, a synergistic effect between benznidazole and the CV chemical analogues LTD-CPH-CFZ was evidenced by combination and dose-reduction indexes values. Taken together, these CV structural analogues could be a starting point to design therapeutic alternatives to treat Chagas disease. Drug repurposing is one of the recommended strategies by the World Health Organization to fight neglected diseases, like Chagas disease, because costs and development time are significantly reduced for its application in therapy.