A novel CDK8 inhibitor with poly-substituted pyridine core: Discovery and anti-inflammatory activity evaluation in vivo.

As an ideal anti-inflammatory target, cyclin-dependent kinase 8 (CDK8) has gradually attracted the attention of researchers. CDK8 inhibition up-regulates Interleukin-10 (IL-10) expression by enhancing the transcriptional activity of activator protein-1 (AP-1), and augmenting IL-10 abundance is a viable strategy for the treatment of inflammatory bowel disease (IBD). In this research, through structure-based drug design and dominant fragment hybridization, a series of poly-substituted pyridine derivatives were designed and synthesized as CDK8 inhibitors. Ultimately, compound CR16 was identified as the best one, which exhibited good inhibitory activity against CDK8 (IC50 = 74.4 nM). In vitro and in vivo studies indicated that CR16 could enhance the transcriptional activity of AP-1, augment the abundance of IL-10, and affect CDK8-related signaling pathways including TLR7/NF-κB/MAPK and IL-10-JAK1-STAT3 pathways. In addition, CR16 showed potent therapeutic effect in an animal model of IBD.

Non-peptidyl non-covalent cathepsin C inhibitoEEr bearing a unique thiophene-substituted pyridine: Design, structure-activity relationship and anti-inflammatory activity in vivo.

Cathepsin C (Cat C) is involved in inflammation regulation by activating neutrophil serine proteases (NSPs). Therefore, Cat C is an attractive target for treatment of inflammatory diseases mediated by NSPs overactivation. In previous study, compounds 54 and 77 were reported to be the first non-peptidyl non-covalent Cat C inhibitors, with good enzyme inhibitory activity and NSPs activation inhibition, but their pharmacokinetic (PK) properties were unsatisfactory. In this study, starting from 77, after several rounds of structure-based design and modification, compound SF38, a novel Cat C inhibitor bearing a unique thiophene structure was identified, which exhibited strong inhibitory activity against Cat C (IC50 = 59.9 nM). Further mechanism study and in vivo evaluation showed that SF38 inhibited the Cat C activity in bone marrow and blood, decreased the activation of NSPs, and exhibited anti-inflammatory activity in an animal model of acute lung injury, with acceptable PK properties (F = 42.07%). These results enriched the structure-activity relationship (SAR) of Cat C inhibitor with thiophene structure characteristic, and proved the broad prospect of non-peptidyl non-covalent Cat C inhibitor.

Discovery and Anti-Inflammatory Activity Evaluation of a Novel CDK8 Inhibitor through Upregulation of IL-10 for the Treatment of Inflammatory Bowel Disease In Vivo.

Increasing the anti-inflammatory cytokine interleukin-10 (IL-10) level is a promising strategy to suppress the progression of pathogenic inflammation including inflammatory bowel disease (IBD). Since cyclin-dependent kinase 8 (CDK8) inhibition can upregulate IL-10 abundance in activated myeloid-derived dendritic cells, it is considered to be an effective target for IBD treatment. Here, the complete discovery process of a novel CDK8 inhibitor as an anti-inflammatory agent was described. Starting with wogonin, structure-based optimization and structure-activity relationship (SAR) study were comprehensively carried out, and then lead compound 85 (N-(2-ethylphenyl)-5-(4-(piperazine-1-carbonyl)phenyl)nicotinamide) was developed as a potent druglike CDK8 inhibitor upregulating IL-10 both in vivo and in vitro. Also, compound 85 (with CDK8 IC50 = 56 nM, IL-10 enhancement rate 88%) exhibited effective anti-inflammatory activity in an animal model of IBD. These results confirmed that certain CDK8 inhibitor could be used as an effective anti-IBD drug.