Strategies for the isolation and identification of trypanocidal compounds from the Rutales

Crude extracts of Rutales species were tested in vitro against the trypomastigote form of Trypanosoma cruzi at 4 mg/mL, and 20% of them showed significant activity (greater than or equal to 80%). Their inhibitory activity against the glycolytic enzyme GAPDH from T. cruzi has also been evaluated at the concentrations of 100 and 200 mug/mL. Additionally, the inhibitory activity of 13 purified coumarins were also assayed against T. cruzi-GAPDH. Chalepin was the most active substance with IC50 = 64 muM. The 3D structure of the complex chalepin-enzyme was elucidated by X-ray crystallography, revealing the architecture of the interactions between the inhibitor and the enzyme active site.