Synthesis by Microwave Irradiation, Molecular Structural Analysis and Trypanocidal Activity of Novel Pyrazole-tetrahydropyrimidine Derivatives

Background A series of new eight 2-(1-aryl-3-methyl-1H-pyrazol-4-yl)-1,4,5,6-tetrahydropyrimidines 1(a-h) were synthesized by microwave irradiation technique. In vitro phenotypic screening was performed to evaluate the effect of these compounds on intracellular amastigotes forms of Trypanosoma cruzi, the etiological agent of Chagas disease. Methods Compounds 1(a-h) were synthesized from pyrazole-carbonitriles 2(a-h) employing microwave irradiation (50W) for 10-20 minutes. Physicochemical properties were calculated using OSIRIS DataWarrior. The toxic effect on mammalian cells (Vero Cells) and the trypanocidal activity against Trypanosoma cruzi (Dm28c-Luc) were also evaluated. Results Compounds 1(a-h) were obtained in 24-94% yields. They were completely characterized by Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR) and High-Resolution Mass Spectrometry (HRMS) analyses. The derivatives showed low trypanocidal activity, with IC50 ranging from 47.16 to > 100 & mu;M, with lower activity than benznidazole (1.93 & mu;M) used as reference drug. Conclusion The attractive features of this synthetic methodology are mild conditions, short reaction time, and low power. All derivatives showed low toxicity in mammalian cells, good oral bioavailability, and did not violate Lipinski & PRIME;s rule of 5.