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 1 H NMR, 13 C 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 4ı as potent and selective MAO A inhibitors. The most active compound 4ı , which is 2,4‐dimethoxy at phenyl ring, showed strong inhibitory activity at MAO A (IC 50 of 0.0445 ± 0.0018μM). Furthermore, compounds 4c and 4d showed significant inhibition profile on MAO A with the IC 50 values 0.1423 ± 0.0051μM and 0.2148 ± 0.0067μM, respectively.