Synthesis and biological evaluation of (1-aryl-1H-pyrazol-4-yl) (3,4,5-trimethoxyphenyl)methanone derivatives as tubulin inhibitors.

A series of (1-aryl-1H-pyrazol-4-yl) (3,4,5-trimethoxyphenyl)methanones (8a-p, 9a-p) and ketoxime (10c) derivatives were designed and synthesized as antitubulin agents. All of the target compounds were evaluated for the in vitro anti-proliferative activities against three tumor cell lines (A549, HT-1080, SGC-7901). The most promising compounds in this class were (1-(p-tolyl)-1H-pyrazol-4-yl) (3,4,5-trimethoxyphenyl)methanone (9c) and its ketoxime derivative (10c), which significantly inhibited tumor cells growth with IC value of 0.054-0.16 μM. Meanwhile, compound 9c exhibited effectively inhibitory activity of tubulin polymerization. Consistent with its antitubulin activity, compound 9c could destructively damage microtubule network and arrest SGC-7901 cell cycle at G2/M phase significantly. The structure-activity relationship (SAR) and conformational analysis indicate that methyl group at C4-position of C-ring is critical for the activities and the amino group at the C5-position of B-ring plays a negative role in maintaining bioactivity. Furthermore, a molecular docking study was performed to elucidate its binding mode at the colchicine site in the tubulin heterodimer.