Synthesis and evaluation of new pyrazoline-thiazole derivatives as monoamine oxidase inhibitors

A novel series of 1,3,5-trisubstituted-2-pyrazoline derivatives (4a-4k) was synthesized and their chemical structures characterized by H-1 NMR, C-13 NMR, and mass spectroscopy. These compounds were evaluated as inhibitors for of type A and type B monoamine oxidase (MAO) enzymes. The most common inhibitors of MAO enzymes used to treat depression and anxiety such as selegiline and moclobemide drugs were used as reference agents. A result of biological evaluation of these compounds revealed compounds 4c, 4d, and 4i as potent and selective MAO A inhibitors. The most active compound 4i, which is 2,4-dimethoxy at phenyl ring, showed strong inhibitory activity at MAO A (IC50 of 0.0445 +/- 0.0018 mu M). Furthermore, compounds 4c and 4d showed significant inhibition profile on MAO A with the IC50 values 0.1423 +/- 0.0051 mu M and 0.2148 +/- 0.0067 mu M, respectively.