Hydrogenation of the 3,4 alkene moiety resulted in the chromatographically separable piperidines 9 and 10.
15 Receptor bound Stats are phosphorylated, dimerize and translocate towards the nucleus to trigger gene transcription. To examine cellular Jak3 activity directly, we analyzed enriched, human CD4 T cells isolated from PBMCs incubated with every single compound at relevant concentrations along with a DMSO control before stimulation deacetylase inhibitor with IL 2. The degree of Stat5 phosphorylation was analyzed from cell lysates via immunoblotting with an anti phospho Stat5 mAb. From this experiment it was clear that only CP 690,550 maintained the ability to affect Stat5 phosphorylation at the concentrations tested, highly suggesting that the alternate stereochemical configurations of the molecule had deleterious effects on Jak3 inhibition.
Further, 1 represents a novel and unique chemotype for kinase inhibition and it was of interest to profile each stereoisomer across a panel of kinases. Recently, Ambit Biosciences reported the aforementioned PARP quantitative analysis of 38 known kinase inhibitors across a panel of 317 kinases. 9 We submitted 1 and the stereoisomeric analogues 2, 3 and 4 across the same panel. The initial profile provides activity as a percentage of DMSO control. Activities beyond a selected threshold were submitted for Kd determinations and the results are shown as a dendrogram representation in Figure 3. The profile of 1 closely matched the published data. The profile additionally found a Kd of 210 nM for 1 at Rock. Full Kd determinations for 1 were pursued for the 4 related Jak targets as well as the Jak1. These Dinaciclib results confirmed that 1 binds Jak3 and Jak2 nearly equipotently.
Mst and Map4K kinase subfamilies reside on the related STE20 and STE7 branches of the kinome. That enantiomers 2 and 4 show activity at these related targets suggests that this chemotype may represent a novel starting point for the development of selective inhibitors of these important kinase Dinaciclib classes.
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