Discovery of pyrrolospirooxindole derivatives as novel cyclin dependent kinase 4 (CDK4) inhibitors by catalyst-free, green approach

Aiming to develop a new target for the anticancer treatment, a series of 5′H-spiro[indoline-3,4′-pyrrolo [1,2-A]quinoxalin]-2-ones has been synthesized by simple, highly efficient and environmentally friendly method in excellent yields under catalyst-free conditions using ethanol as a green solvent. A simple filtration of the reaction mixture and subsequent drying affords analytically pure products. The synthesized derivatives were evaluated for their antiproliferative activity against five different human cancer cell lines, among the congeners compound 3n showed significant cytotoxicity against the human prostate cancer (DU-145). Flow cytometric analysis revealed that this compound induces cell cycle arrest in the G0/G1 phase and Western blot analysis suggested that reduction in Cdk4 expression level leads to apoptotic cell death. This was further confirmed by mitochondrial membrane potential (("m), Annexin V-FITC assay and docking experiments. Furthermore, it was observed that there is an increase in expression levels of cyclin dependent kinase inhibitors like Cip1/p21 and Kip1/p27.