Tubulin inhibitor 51 is a selective Tubulin inhibitor with an IC50 value of 5.41 μM. It exhibits notable anti-proliferative activity, possesses a unique reactive oxygen species-mediated apoptosis mechanism, and demonstrates strong anti-microtubule activity. Tubulin inhibitor 51 is applicable to anti-tumor research.

Tubulin inhibitor 51 (Compound 4a) exhibits potent activity against 15 cancer cell lines at 10 μM, showing lethality towards SF-539 and CAKI-1 cells with GI values of 112.22% and 150.64%, respectively. It demonstrates high activity and selectivity with IC 50 values of 3.46 μM for OVCAR-4, 5.93 μM for A549, and 42.71 μM for non-tumor cells WI-38. At 6 μM for 20 minutes, it inhibits microtubule polymerization in A549 cells with an IC 50 of 5.41 μM. At 5.93 μM over 48 hours, it arrests the cell cycle at the G2/M phase (34.8%) in A549 cells, inhibits cancer cell proliferation, induces 85% cell death, primarily in early-stage A549 cells, and significantly increases reactive oxygen species levels by 2.4-fold. Tubulin inhibitor 51 also causes a 56-67% loss of mitochondrial membrane potential in A549 cells, similar to the control CA-4.