Design and Synthesis of New CDK2 Inhibitors Containing Thiazolone and Thiazolthione Scafold with Apoptotic Activity.

Cyclin dependent kinase 2 (CDK2) inhibition is a well-established strategy for treating cancer. Different series of novel thiazolone (1, 7-9) together with fused thiazolthione (2-6, and 10) derivatives were designed, then synthesized and evaluated for their biological inhibitory activity against CDK2. Additionally, the cytotoxicity of the new compounds was explored against breast and colon cancer cell lines. The novel thiazolone and the fused thiazolthione derivatives exhibited potent CDK2/cyclin A2 inhibitory effect of an IC50 values ranging 105.39-742.78 nM. Amongst them compounds 4 and 6 revealed highest IC50 of 105.39 and 139.27 nM, respectively. Most compounds showed significant inhibition on both breast cancer and colon cancer cell lines with IC50 range 0.54-5.26 and 0.83-278 µM, respectively. Further investigations involved flow cytometry analysis on MCF-7 cancer cell line for compounds 5 and 7 which resulted in arrest cell-cycle at two phases Pre G1/G2-M and re-enforced apoptosis via activation of caspase-7. Molecular modeling simulation of the designed compounds revealed that they were well fitted into CDK2 active site and their complexes were stabilized through the essential hydrogen bonding. Three dimensional quantitative structure activity relationship (3D QSAR) pharmacophore, and absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies were also carried out showing proper pharmacokinetic and drug-likeness which aided in the prediction of the structure requirements responsible for the observed antitumor activity.

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION OF NEW FUSED TRIAZINE DERIVATIVES BASED ON 6-METHYL-3-THIOXO-1,2,4-TRIAZIN-5-ONE.

A one-pot reaction of 6-methyl-3-thioxo-3,4-dihydro-[1,2,4]triazin-5-one 1 with selected aldehydes 2a-d and chloroacetic acid afforded the respective 2-arylidene-6-methyl-thiazolo[3,2-b][1,2,4]triazine-3,7-diones 4a-d. Compunds 4a-d could be also obtained via the reaction of 1 with chloroacetic acid in refluxing acetic acid to give 6-methyl-thiazolo[3,2-b][1,2,4]triazine-3,7-dione 3 then, Knoevenagel condensation of 3 with aldehydes 2a-d gave compounds 4a-d. Heterocyclization of 4a-c with hydrazine hydrate and phenylhy- drazine gave the corresponding pyrazolines 5a-c and 6a-c, respectively. Moreover, 7-amino-9-(aryl)-3-methyl-2-oxo-2H-pyrido[2',3':4,5][1,3]thiazolo[3,2-b][1,2,4]triazine-8-carbonitrles 7a-c were synthesized by the reaction of 4a-c with malononitrile in the presence of ammonium acetate. The structures of newly synthesized compounds were confirmed by analytical and spectroscopic measurements. Some selected new compounds were screened for their cytotoxic activities against three human cancer cell lines (HepG2, MCF-7 and A549) using SRB assay and the structure-activity relationship (SAR) was discussed. The biochemical assays including antioxidant enzyme, oxidative stress and estimation of nucleic acids and proteins have been discussed for some selected compounds. The molecular docking of 4c and 7b has been also studied.