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| Author(s): |
Américo Tavares Ranzani
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2017-08-25 |
| Examining board members: |
Artur Torres Cordeiro;
Ariel Mariano Silber;
Marcio Vinicius Bertacine Dias;
Juliana Ferreira de Oliveira;
João Renato Carvalho Muniz
|
| Advisor: | Artur Torres Cordeiro |
| Abstract | |
American trypanosomiasis, or Chagas Disease, is caused by the protozoan Trypanosoma cruzi. The treatment is based on drugs that present serious side effects and are inefficient against the chronic phase of the disease. The research in new metabolic targets may lead to the development of safer and more efficient drugs. Malic enzyme (ME) is considered a promising target due to its ability to produce NADPH, reducing agent that participates in a number of biosynthetic pathways and in detoxication of reactive oxygen species produced from endogenous metabolic reactions or from exogenous immune insults generated by mammalian host cells. T. cruzi expresses two isoforms of the enzyme, one mitochondrial (TcMEm) and other cytosolic (TcMEc). In this thesis, the first characterized inhibitors for these enzymes are reported, identified by a biochemical high-throughput screening (HTS) assay against a library of 30 thousand compounds. IC50 values of 262 molecules were determined for both TcMEs as well as for three human ME isoforms, with the inhibitors clustered into six groups according to their chemical similarity. The most potent hits belonged to group ATR3, comprised of 218 aryl-sulfonamides that specifically target TcMEc. Moreover, several selected inhibitors of both TcMEs showed trypanocidal effect against the replicative forms of T. cruzi. Also, in this work the first crystallographic structures of both TcMEs are shown, revealing different features from the human homologues. In addition, the complex of TcMEc with 6 different ATR3 molecules were determined, unravelling the inhibition site at the dimer interface. In conclusion, the HTS results demonstrate that TcMEs are druggable, being modulated by small hydrophobic molecules, which is an essential requirement for a drug target. Moreover, the identified compounds can be used as chemical probes in the validation of the enzymes. The enzyme structures are important tools which may be employed to design new inhibitors or analogues (AU) | |
| FAPESP's process: | 12/23682-7 - Structural characterization of malic enzyme of Trypanosoma cruzi and inhibitor discovery by a High-Throughput Screening assay. |
| Grantee: | Américo Tavares Ranzani |
| Support Opportunities: | Scholarships in Brazil - Doctorate |