Putative role of the aldo-keto reductase from Trypanosoma cruzi (TcAKR) in benznidazole metabolism

GARAVAGLIA, PA; LAVERRIERE, M; CANNATA, JB; GARCIA, GA

ANTIMICROBIAL AGENTS AND CHEMOTHERAPY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2016 vol. 60 p. 2664 - 2670

0066-4804

Benznidazole (Bz), the drug used for treatment of Chagas? disease (caused by the protozoan Trypanosoma cruzi), is activated by a parasitic NADH-dependent nitroreductase (NTR I). However, several studies have shown that other enzymes are involved. The aim of this study was to evaluate whether the aldo-keto reductase from T. cruzi (TcAKR), a NADPH-dependent oxido-reductase previously described by our group, uses Bz as substrate. We demonstrated that both recombinant and native TcAKR reduce Bz by using NADPH, but not NADH, as co-factor. TcAKR-overexpressing epimastigotes showed higher NADPH-dependent Bz reductase activity and a 50% inhibitory concentration (IC50) value for Bz 1.8-fold higher than controls, suggesting that TcAKR is involved in Bz detoxification instead of activation. To understand the role of TcAKR in Bz metabolism, we studied TcAKR expression and NADPH/NADH-dependent Bz reductase activities in two T. cruzi strains with differential susceptibility to Bz: CL and Nicaragua. Taking into account the results obtained with TcAKR-overexpressing epimastigotes, we expected that the more resistant strain, Nicaragua, had higher TcAKR levels than CL. However, the results were the opposite. CL showed 2-fold higher TcAKR expression and 5.7-fold higher NADPH-Bz reduction than Nicaragua. In addition, NADH-dependent Bz reductase activity, characteristic of NTR I, was also higher in CL than in Nicaragua. We conclude that, although TcAKR uses Bz as substrate, TcAKR activity is not a determinant of Bz resistance in wild type strains and may be overcome by other enzymes involved in Bz activation, as NADPH- and NADH-dependent reductases.