New inhibitors of metabolite transporters exhibit anti-Trypanosoma cruzi activity

PEREIRA, CA; VALERA-VERA, EDWARD; SAYE, MELISA; MIRANDA, MARIANA; REIGADA, CHANTAL

Caxambú

Congreso; XXXV Meeting of the Brazilian Society of Protozoology/XLIV Annual Meeting on Basic Research in Chagas disease; 2019

Brazilian Society of Protozoology (SBPz)

Polyamines are aliphatic polycations that participate in cell growth and differentiation. In Trypanosomacruzi the transport of polyamines from the extracellular medium is an essential process because thisorganism is unable to synthesize de novo these compounds. In a similar way, the amino acid prolineis also involved in differentiation processes, cellular invasion and resistance to oxidative, nutritionaland osmotic stress. In our laboratory we previously identified in the genome of T. cruzi a multigenefamily of amino acid and polyamine transporters called TcAAAP (Amino Acid/Auxin Permeases). Twomembers of this family, the putrescine/spermidine and proline permeases, were functionallycharacterized and studied as drug targets. In order to identify inhibitors of these permeases,computational simulations combined with in vitro assays were applied. In the case of the prolinepermease, for the similarity-based virtual screening, the compound crystal violet was selected as astarting point. Crystal violet was used in blood banks as a trypanocidal agent (discontinued due to itshigh toxicity) whose mechanism of action involves the inhibition of proline transport. To search forpolyamine permease inhibitors, the reference molecule was an experimental oncological drug formedby a conjugate of a polyamine (putrescine) with anthracene called ANT4 that acts as a potent inhibitorof the polyamine transport in mammalian cells. Using these compounds, a similarity screening wasperformed on structures databases of approved compounds to use in humans using molecule shapeand electrostatic potential comparison algorithms. Three drugs (loratadine, cyproheptadine andclofazimine) were found to be inhibitors of the proline permease in vitro and also had trypanocidalactivity with IC50 between 1 and 13 μM in trypomastigote and amastigote forms. In the case of thepolyamine transporter, other three drugs (promazine, chlorpromazine and clomipramine) showed tobe transport inhibitors and trypanocidal agents with IC50 between 1 and 4 μM. The strategy hereinapplied, based on the screening of approved compounds used to treat other pathologies, is known asdrug repurposing or drug repositioning. One of the main advantages of this experimental approach is that reduces the time and the economic cost of implementation of new therapeutic alternatives, whichis especially important in neglected diseases, like Chagas.