Imidazolyl benzimidazoles and imidazo[4,5-b]pyridines as potent p38alpha MAP kinase inhibitors with excellent in vivo antiinflammatory properties.

Herein we report investigations into the p38alpha MAP kinase activity of trisubstituted imidazoles that led to the identification of compounds possessing highly potent in vivo activity. The SAR of a novel series of imidazopyridines is demonstrated as well, resulting in compounds possessing cellular potency and enhanced in vivo activity in the rat collagen-induced arthritis model of chronic inflammation.

Complete inhibition of anisomycin and UV radiation but not cytokine induced JNK and p38 activation by an aryl-substituted dihydropyrrolopyrazole quinoline and mixed lineage kinase 7 small interfering RNA.

Mixed lineage kinase 7 (MLK7) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that activates the pro-apoptotic signaling pathways p38 and JNK. A library of potential kinase inhibitors was screened, and a series of dihydropyrrolopyrazole quinolines was identified as highly potent inhibitors of MLK7 in vitro catalytic activity. Of this series, an aryl-substituted dihydropyrrolopyrazole quinoline (DHP-2) demonstrated an IC50 of 70 nM for inhibition of pJNK formation in COS-7 cell MLK7/JNK co-transfection assays. In stimulated cells, DHP-2 at 200 nM or MLK7 small interfering RNA completely blocked anisomycin and UV induced but had no effect on interleukin-1beta or tumor necrosis factor-alpha-induced p38 and JNK activation. Additionally, the compound blocked anisomycin and UV-induced apoptosis in COS-7 cells. Heart tissue homogenates from MLK7 transgenic mice treated with DHP-2 at 30 mg/kg had reduced JNK and p38 activation with no apparent effect on ERK activation, demonstrating that this compound can be used to block MLK7-driven MAPK pathway activation in vivo. Taken together, these data demonstrate that MLK7 is the MAPKKK required for modulation of the stress-activated MAPKs downstream of anisomycin and UV stimulation and that DHP-2 can be used to block MLK7 pathway activation in cells as well as in vivo.

Synthesis and in vitro antimicrobial activity of 3-keto 16-membered macrolides derived from tylosin.

Several series of 14-membered ketolides derived from erythromycin exhibit useful antimicrobial activity against macrolide-resistant bacteria. To determine if 16-membered ketolides may possess analogous activity, 3-keto derivatives of 5-O-mycaminosyl-23-O-acetyltylonolide and desmycosin were synthesized by protection of susceptible functional groups, oxidation of the 3-hydroxyl group under modified Moffatt-Pfitzner conditions, and subsequent deprotection. The resulting 3-keto products unexpectedly adopted the 2,3-trans enol rather than the 3-keto tautomer. The trans configuration of the 2,3-double bond in the macrolide chain is most likely the result of hydrogen bond stabilization between the enol hydroxyl and lactone carbonyl, which places these two groups in a cis relationship. This preference for the enol tautomer in 16-membered macrolides is not seen with 14-membered ketolides. The in vitro antimicrobial activity of the enol derivatives was greatly reduced compared to their unoxidized parent compounds, but the reduced antimicrobial activity of the enol derivatives paralleled results from corresponding 2,3-anhydro derivatives of 16-membered macrolides, which also have 2,3-trans stereochemistry. These results are in contrast to those from 14-membered-ring macrolides in which 3-keto and 2,3-anhydro derivatives exhibit greater activity than 3-hydroxy compounds.