Design and synthesis of novel 2-pyrazoline-1-ethanone derivatives as selective MAO inhibitors

Thirty seven novel 2-pyrazoline-1-ethanone derivatives were designed, synthesized and evaluated as selective hMAO inhibitors. Among them, compounds 7h (IC50 = 2.40 μM) and 12c (IC50 = 2.00 μM) exhibited best inhibitory activity and selectivity against hMAO-A, surpassing that of the positive control Clorgyline (IC50 = 2.76 μM). Based on selective activity of hMAO-A, SAR analysis showed that the order of N1 substituent contribution was bromo (3) > piperidinyl (4) > morpholinyl (5) > imidazolyl (6), and compounds with electron-withdrawing substituents (-F, -Cl) at C3 or C5 phenyl ring of 2-pyrazoline nucleus dedicated stronger MAO-A inhibitory activity. Molecular docking showed that compounds 7h and 12c were nicely bound to hMAO-A via two hydrogen bonds (SER209, GLU216), one Pi–Pi interaction and three hydrogen bonds (SER209, GLU216, TYR69), one Sigma–Pi interaction, respectively. In addition, the substituent at C3 position of 2-pyrazoline with the N1 acetyl has little effect on MAO-A inhibitory activity. These data support further studies to assess rational design of more efficiently selective hMAO inhibitors in the future.

Novel 2-pyrazoline-1-ethanone derivatives as potential MAO selectivity inhibitors were designed and synthesized. Enzymatic assays revealed that compound 12c exhibited strong selectivity inhibitory activity toward hMAO-A.Figure optionsDownload as PowerPoint slide