Design and synthesis of substituted dihydropyrimidinone derivatives as cytotoxic and tubulin polymerization inhibitors

An operationally simple Biginelli protocol was employed for the synthesis of new C6-carbon based aryl alpha-haloacrylamide-linked dihydropyrimidinone derivatives. The synthesized compounds were appraised for their in vitro antiproliferative potential against a selected panel of human cancer cell lines especially MCF-7 (human breast cancer), MDA-MB-231 (human breast cancer), HCT-116 (human colon cancer), HCT-15 (human colorectal adenocarcinoma), HT-29 (human colon adenocarcinoma) and DU145 (human prostate cancer) along with normal lung fibroblasts (HFL-1). Preferably, compounds containing alpha-haloacrylamide (10a-g) functionality were found to exhibit most significant cytotoxicity (IC50 value 0.54 +/- 0.12 to 8.35 +/- 0.82 mu M) against the listed cancer cell lines, particularly towards breast cancer cell lines MCF-7 and MDA-MB-231 (IC50 value 0.54 +/- 0.12 to 3.70 +/- 0.24 mu M). In the seam of synthesized compounds, compound 10f exhibited potent antiproliferative activity against breast cancer cell lines namely MCF-7 (IC50 value 0.54 +/- 0.12 mu M) and MDA-MB-231 (IC50 value 1.18 +/- 0.32 mu M). Further to understand the underlying apoptosis mechanisms, different staining techniques such as AO/EB, DCFDA, and DAPI staining were performed. To know the extent of apoptosis and loss of mitochondrial membrane potential in MCF-7 cell lines, annexin V-FITC/PI and JC-1 were performed. Cell cycle analysis revealed that compound 10f arrested the cells at G2/M phase in a dose-dependent manner. The compound 10f also found to exhibit significant inhibition of tubulin polymerization (IC50 of 6.91 +/- 0.43 mu M) with microtubule destabilizing properties. Molecular docking studies also revealed that compound 10f efficiently interacted with critical catalytically active residues Ser178, Val238, and Val318 of the alpha/beta-tubulin by a hydrogen bond.