Design, synthesis and biological evaluation of novel scaffold benzo[4,5]imidazo [1,2-a]pyrazin-1-amine: Towards adenosine A2A receptor (A2A AR) antagonist.

Antagonists of adenosine receptor are under exploration as potential drug candidates for treatment of neurological disorders, depression, certain cancers and potentially used as a cancer immunotherapy. Herein, we describe design and synthesis of novel scaffold benzo[4,5]imidazo [1,2-a]pyrazin-1-amine (6) derivatives. All the compounds were evaluated for A2A AR antagonist activity and displayed encouraging results (IC50 9-300 nM) of A2A AR antagonist binding affinity in biochemical assay. Compound 27 exhibits good activity in A2A AR antagonist cAMP functional assay (IC50 31 nM) and further this compound shows T-cell activation at the IL-2 production assay (EC50 165 nM). Molecular docking studies were carried out to rationalize the observed binding affinity of compound 27.

Differentiation of human neuroblastoma cell line IMR-32 by sildenafil and its newly discovered analogue IS00384.

Sildenafil, a phosphodiesterase-5 inhibitor is FDA approved drug against erectile dysfunction. It is currently undergoing many clinical trials, alone or in combinations against different diseases. Treatment of neural progenitor cells with sildenafil is known to regulate their basal cGMP levels and enhance neurogenesis and differentiation. cGMP as well as cAMP are known to play a central role in the maintenance, repair and remodelling of the nervous system. In the present study, we report the neurodifferentiation property of sildenafil in neuroblastoma cancer cell line IMR-32. Sildenafil was found to induce the formation of neurite outgrowths that were found expressing neuronal markers, such as NeuN, NF-H and ßIII tubulin. IS00384, a recently discovered PDE5 inhibitor by our laboratory, was also found to induce neurodifferentiation of IMR-32 cells. The effect of IS00384 on differentiation was even more profound than sildenafil. Both the compounds were found to elevate and activate the Guanine nucleotide exchange factor C3G, which is a regulator of differentiation in IMR-32 cells. They were also found to elevate the levels of cGMP and activate the AMPK-ACC and PI3K-Akt signalling pathways. These pathways are known to play important role in cytoskeletal rearrangements necessary for differentiation. This study highlights the role of phosphodiesterases-5 in neurodifferentiation and use of sildenafil and IS00384 as small molecule tools to study the process of cellular differentiation.

Synthesis of 5-substituted-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one analogs and their biological evaluation as anticancer agents: mTOR inhibitors.

A microwave assisted strategy for synthesis of series of 1H-pyrazolo[4,3-d]pyrimidin-7(6H)-ones has been developed and their biological evaluation as anticancer agents is described. The synthetic protocol involves simple procedure by oxidative coupling of 4-amino-1-methyl-3-propyl-1H-pyrazole-5-carboxamide with different aldehydes in presence of K2S2O8 offering 5-substituted-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one compounds in excellent yields. The in vitro anticancer activity screening against human cancer cell lines HeLa, CAKI-I, PC-3, MiaPaca-2, A549 gave good results. The in detailed mechanistic correlation studies of compound 3m revealed that the compound shows anticancer activity through apoptosis mechanism and also inhibits mTOR with nonomolar potency. The design was based on docking with mTOR protein. The concentration dependent cell cycle analysis, western blotting experiment and nuclear cell morphology studies have been described.