N‐(Indazolyl)benzamido Derivatives as CDK1 Inhibitors: Design, Synthesis, Biological Activity, and Molecular Docking Studies

Abstract

A series of N-1H-indazole-1-carboxamides has been synthesized and their effects on both CDK1 / cyclin B and the K-562 (human chronic myelogenus leukemia) cell line were evaluated. Using a computational model, we have observed that all the most active compounds 9e, f, i -n exhibited the same binding mode of purvanalol A in the ATP-binding cleft. Although they were able to moderately inhibit the leukemic cell line K-562 and to show inhibitory activity against the Cdc2-Cyclin B kinase in the low micromolar range, they turned out to be non-cytotoxic against HuDe (IZSL) primary cell cultures from human derm. These preliminary results are quite encouraging in view of the low toxicity demonstrated by the above-mentioned compounds. Introduction 2,6,9-Substituted purine derivatives represent a class of potent and selective inhibitors of cyclin-dependent protein kinase (CDK) that have recently been found to be of potential use as anticancer drugs [1 -3]. In particular, olomoucine 1 [4], roscovitine 2 [5], purvalanol A 3 [6], O 6 -cyclohexylmethylguanine (NU2058) 4, and its analoge NU61025 [7] are significant examples of such kind of molecules ( Fig. 1).They act by competing with ATP for binding in the CDK catalytic site located in a deep cleft between the two lobes of the protein kinase [8].Four key features are essential for the interaction with CDKs, the presence of the flat hydrophobic purine ring and the opportune substitutions in the position 2, 6, and 9. The purine ring allows the interaction of the molecules with the hinge region, a flexible fragment consisting of 81 to 84 residues that connects the two lobes of the kinases [9]. In particular, ATP adenine moiety hydrogenbonds the backbone oxygen of Glu81 and the backbone nitrogen of Leu 83, and these hydrogen bonds are typically emulated by the CDK inhibitors that bind to the hinge region; a third hydrogen bond to the backbone oxygen of Leu 83 has also been observed for olomoucine 1, roscovitine 2, purvalanol A 3, and NU2058 4 [9, 10].As a part of our research, we synthesized some N-(heteroaryl)-2-iodobenzamides 6a -p with the aim of ascertain their activity as fungicides (Scheme 1) [11,12].Among the synthesized benzamides, the N-(indazol-3-yl)benzamides 6o, p have drawn our attention as potential CDK inhibitors because they contain the characteristic, common to the majority of CDK inhibitors, the capability to make hydrogen bonds with the molecular fork present in the hinge region of CDKs [9] (Fig. 2).On the basis of the structures of known potent CDK inhibitors, we foresaw the following structural modifications on the N-(indazol-3-yl)benzamido skeleton: the Life Sci. 2009, 342, 265 -273 introduction of various substituents on the benzamido moiety and its displacement from the 3-position of the indazole nucleus to the 5-and 6-positions, the amidic function inversion, and the substitution of the benzamido moiety with the phenoxyacetamido and phenylacetamido ones, with the goal to identify potent low molecular weight inhibitors of CDK1 that act by preventing the...

Indazole- and Indole-5-carboxamides: Selective and Reversible Monoamine Oxidase B Inhibitors with Subnanomolar Potency

“…Products 10 – 14 and 16 were obtained as shown in Scheme . Compound 14 had previously been described, , but in the present study we used different reaction conditions to obtain 14 in higher yields. The carboxylic acids 18 and 19 were prepared by two- or three-step reaction procedures according to published procedures (for details, see Supporting Information).…”

“… a Reagents and conditions: (i) for 10 – 14 , carboxylic acid 18 , 19 , or 21a – c (1.0 equiv), 5-amino-1 H -indazole ( 17 , 1.0 equiv), TBTU/DIPEA (1.2 equiv), acetonitrile, RT, 3–72 h, yield 23–73%; (ii) for 16 , 2-(3,4-dichlorophenyl)­acetic acid ( 20 , 1.0 equiv), 5-amino-1 H -indazole ( 17 , 1.0 equiv), EDC–HCl (1.1 equiv), methanol, RT, 3–4 h, yield 56% ( 16 ). …”

Synthesis and biological evaluation of new indazole derivatives

“…The structure was solved by direct methods, 19 ) (human colon cancer) and MCF-7 (breast cancer) cell lines were performed by general methods previously described. 22,23 The ability of the test compound to inhibit the conversion of arachidonic acid to prostaglandin H 2 (PGH 2 ) was determined using a COX1/COX2 inhibitor screening assay kit (cat. n#560101;Cayman Chemical, Ann Arbor, MI).…”