Discovery of a biologically active Trypanosoma cruzi bromodomain inhibitor by target-directed dynamic combinatorial chemistry

GARCIA, PAULA; SERRA, ESTEBAN CARLOS; TAVERNELLI, LUIS EMILIO; FURLÁN, RICARDO; ALONSO, VICTORIA LUCÍA; ESCALANTE, AYELÉN

Buenos Aires

Congreso; Drug Discovery for Neglected Diseases International Congress 2018; 2018

Instituto de la Química y Metabolismo del Fármaco

Bromodomains are the only protein domains capable of recognizing and interacting with acetylated lysines. Trypanosoma cruzi, the causal agent of Chagas disease, presents an atypical bromodomain (TcBDF3) that interacts with acetylated α-tubulin present in the cytoskeleton and flagella of this parasite. TcBDF3 is an interesting target for the development of new trypanocidal drugs that interrupt the Bromodomain-acetylated ligand interaction due to its essentiality in the differentiation of T. cruzi. Target-directed dynamic combinatorial chemistry has emerged as a strategy for the identification of inhibitors of relevant therapeutic targets. We used this strategy for the identification of TcBDF3. A small dynamic library of acylhydrazones was prepared from aldehydes and acylhydrazides at neutral pH in presence of aniline as catalyst. When a protein is added to the equilibrium mixture, and if the protein interacts with any components of the combinatorial library, the position of the equilibrium will shift and those components that interact with the protein will be amplified. We have set up a library of acylhydrazones that would display a variety of functional groups potentially capable of interact with the hydrophobic pocket of TcBDF3.We observed the amplification of one member of the library in the presence of recombinant TcBDF3 using HPLC-DAD and HPLC-MS. This compound binds specifically to recombinant TcBDF3, with a dissociation constant of 1.7 M, measured by fluorescence quenching and Thermal shift. We also observed a cytotoxic effect in all life cycle stages of Trypanosoma cruzi similar to the drug Benznidazol, currently use as therapy but with numerous and severe side effects. In summary, the most amplified library member shows: (a) high affinity for the template, (b) interesting antiparasitic activity against different parasite forms and (c) low toxicity against Vero cells. In addition, parasites are rescued from the compound toxicity by TcBDF3 overexpression, suggesting that the toxicity of this compound is due to the TcBDF3 inhibition i.e. the binding event that initially drives the molecular amplification, is reproduced in the parasite leading to selective toxicity.These results validate this strategy to search for novel candidates against Chagas disease by targeting bromodomains.