IDENTIFICATION OF NEW TRYPANOCIDAL COMPOUNDS THAT INHIBIT PUTRESCINE UPTAKE THROUGH IN SILICO SCREENING AND IN VITRO ASSAYS

DIETRICH R; SBARAGLINI, ML; TALEVI A; ALBERCA, LUCAS N; MORALES, JF; GAVERNET L; RUIZ D; FRACCAROLI L; CARRILLO C

Buenos Aires

Congreso; Reunión conjunta de la Sociedades de Biociencias; 2017

Sociedad Argentina de Protozoología, Sociedad Argentina de Hematología, Sociedad Argentina de Fisiología, Sociedad Argentina de Farmacología Experimental, Sociedad Argentina de Biología, Sociedad Argentina de Biofísica, Sociedad Argentina de Investigación

The polyamines putrescine and spermidine are crucial biomoleculesfor Trypanosoma cruzi. In contrast with human cells, T. cruziis incapable of synthesizing polyamines de novo and incorporatesthem from the extracellular medium. The putrescine permeaseTcPAT12 has been directly linked to the proliferative ability of T.cruzi, and has been proposed as potential target for the discovery ofnovel trypanocidal compounds.The aim of this study was the identification of inhibitors of putrescineuptake in T. cruzi.Using ligand-based approximations, in conjunction with a homologymodel of TcPAT12, we have performed an in silico screening toidentify TcPAT12 potential inhibitors among existing drugs, a strategyknown as drug repositioning, which allows time- and cost-efficientdevelopment of new medications.We compile a database of 256 polyamine analogs that had previouslybeen assayed against T. cruzi. From this dataset, usingDragon molecular descriptors and linear discriminant analysis, weinferred 1000 computational models able to discriminate betweeninhibitors and non-inhibitors of putrescine transport. The 8 best-performingmodels were combined through ensemble learning and appliedin the virtual screening of Drug Bank 3.0 database. The probabilityof being active for the selected compounds was assessedthrough Positive Predictive Value (PPV) surfaces analysis. Hits withPPV ≥30% we submitted to molecular docking using an in-househomology model of TcPAT12. Two hits were selected for in vitro evaluations: the antiemetic cinnarizine (PPV=50.6%) and the antibioticclofazimine (PPV=30.0%). Both drugs inhibited putrescine uptake inT. cruzi epimastigotes and interfered with their proliferation with anEC50 of 6.0μM for cinnarizine and 10.6 μM for clofazimine (previouslyreported). Moreover, both compounds affected trypomastigotesviability.The applied strategy allows identification of potential new drugswith considerable saving of time and material resources.Keywords: Chagas disease, Trypanosoma cruzi, polyamines