Antiproliferative Evaluation of Some 2-[2-(2-Phenylethenyl)-cyclopent-3-en-1-yl]-1,3-benzothiazoles: DFT and Molecular Docking Study.

The 2-[2-(2-phenylethenyl)cyclopent-3-en-1-yl]-1,3-benzothiazoles were synthesized from the reactions of 7-benzylidenebicyclo[3.2.0]hept-2-en-6-ones with 2-aminobenzenethiol. The antiproliferative activities of 2-[2-(2-phenylethenyl)cyclopent-3-en-1-yl]-1,3-benzothiazoles were determined against C6 (rat brain tumor) and HeLa (human cervical carcinoma cells) cell lines using BrdU cell proliferation ELISA assay. Cisplatin and 5-fluorouracil (5-FU) were used as standards. The most active compound was 2-{(1S,2S)-2-[(E)-2-(4-methylphenyl)ethenyl]cyclopent-3-en-1-yl}-1,3-benzothiazole against C6 cell lines with IC50 =5.89 µm value (cisplatin, IC50 =14.46 µm and 5-FU, IC50 =76.74 µm). Furthermore, the most active compound was 2-{(1S,2S)-2-[(E)-2-(2-methoxyphenyl)ethenyl]cyclopent-3-en-1-yl}-1,3-benzothiazole against HeLa cell lines with IC50 =3.98 µm (cisplatin, IC50 =37.95 µm and 5-FU, IC50 =46.32 µm). Additionally, computational studies of related molecules were performed by using B3LYP/6-31G+(d,p) level in the gas phase. Experimental IR and NMR data were compared with the calculated results and were found to be compatible with each other. Molecular electrostatic potential (MEP) maps of the most active 2-{(1S,2S)-2-[(E)-2-(2-methoxyphenyl)ethenyl]cyclopent-3-en-1-yl}-1,3-benzothiazole against HeLa and the most active 2-{(1S,2S)-2-[(E)-2-(4-methylphenyl)ethenyl]cyclopent-3-en-1-yl}-1,3-benzothiazole against C6 were investigated, aiming to determine the region that the molecule is biologically active. Biological activities of mentioned molecules were investigated with molecular docking analyses. The appropriate target protein (PDB codes: 1 M17 for the HeLa cells and 1JQH for the C6 cells) was used for 2-{(1S,2S)-2-[(E)-2-(2-methoxyphenyl)ethenyl]cyclopent-3-en-1-yl}-1,3-benzothiazole and 2-{(1S,2S)-2-[(E)-2-(4-methylphenyl)ethenyl]cyclopent-3-en-1-yl}-1,3-benzothiazole molecules exhibiting the highest biological activity against HeLa and C6 cells in the docking studies. As a result, it was determined that these molecules are the best candidates for the anticancer drug.