Novel Dihydropyrimidinones Synthesized through Modified Biginelli Reaction as Eg5 Kinesin Inhibitors with Potential Anti-cancer Effects: In vitro and In vivo Studies.

Background: Monastrol is a known kinesin Eg5 inhibitor. It is a dihydropyrimidine with 4-(mhydroxyphenyl) substituent. In contrast to taxols and vinca alkaloids, which, through targeting microtubules, affect both normal and cancer cells, kinesin inhibitors selectively target cancer cells.

Objectives: In this study, m-hydroxyphenyl in monastrol was replaced with imidazolyl substituent, which has better water solubility and is found in the structure of many drugs and biologically active compounds. The effects of synthesized compounds were also investigated.

Methods: Three series of monastrol-related dihydropyrimidinone derivatives were synthesized through a modified Biginelli reaction. The newly synthesized compounds were characterized by elemental analysis, LCMS, and NMR. Then, the structure-activity relationship (SAR) of synthesized compounds was evaluated by their toxicity, molecular docking scores, and results of molecular dynamic simulation. The compounds with more potential (4i, 4m, 5a, and 6a) were further investigated in vitro and in vivo for their anti-cancer effects.

Results: The synthesized compounds could effectively reduce the ATPase activity of kinesins, which was consistent with the observation of G2/M arrest of cells in flow cytometry and confocal microscopy results. In addition, an increase in cells in the sub-G1 phase, along with the enhancement of the Bax/Bcl-2 ratio and overexpression of caspases 3, 9, and 8, suggested the apoptosis-inducing effects of compounds. Moreover, compounds showed potent anti-angiogenic effects via altering the expression of genes involved in angiogenesis, which was consistent with the reduced length of capillaries in the CAM test. The synthesized compounds could also demonstrate satisfactory in vivo results in the mice tumor model, which was in accordance with the findings of in vitro experiments.

Conclusion: Novel dihydropyrimidinone derivatives synthesized via modified Biginelli reaction present promising potential as anti-cancer agents.