Metabolically stable dibenzo[b,e]oxepin-11(6H)-ones as highly selective p38 MAP kinase inhibitors: optimizing anti-cytokine activity in human whole blood.

Five series of metabolically stable disubstituted dibenzo[b,e]oxepin-11(6H)-ones were synthesized and tested in a p38α enzyme assay for their inhibition of tumor necrosis factor-α (TNF-α) release in human whole blood. Compared to the monosubstituted dibenzo[b,e]oxepin-11(6H)-one derivatives, it has been shown that the additional introduction of hydrophilic residues at position 9 leads to a substantial improvement of the inhibitory potency and metabolic stability. Using protein X-ray crystallography, the binding mode of the disubstituted dibenzoxepinones and the induction of a glyince flip in the hinge region were confirmed. The most potent compound of this series, 32e, shows an outstanding biological activity on isolated p38α, with an IC50 value of 1.6 nM, extraordinary selectivity (by a factor >1000, Kinase WholePanelProfiler), and low ATP competitiveness. The ability to inhibit the release of TNF-α from human whole blood was optimized down to an IC50 value of 125 nM. With the promising dibenzoxepinone inhibitor 3i, a pharmacokinetic study in mice was conducted.

Targeting the hinge glycine flip and the activation loop: novel approach to potent p38α inhibitors.

The p38 MAP kinase is a key player in signaling pathways regulating the biosynthesis of inflammatory cytokines. Small molecule p38 inhibitors suppress the production of these cytokines. Therefore p38 is a promising drug target for novel anti-inflammatory drugs. In this study, we report novel dibenzepinones, dibenzoxepines, and benzosuberones as p38α MAP kinase inhibitors. Previously reported dibenzepinones and dibenzoxepines were chemically modified by introduction of functional groups or removal of a phenyl ring. This should result in targeting of the hydrophobic region I, the "deep pocket", and the hinge glycine flip of the kinase. Potent inhibitors with IC(50) values in the single digit nanomolar range (up to 3 nM) were identified. Instead of targeting the "deep pocket" in the DFG-out conformation, interactions with the DFG-motif in the in-conformation could be observed by protein X-ray crystallography.

Edaphic and Phytochemical Factors as Predictors of Equine Grass Sickness Cases in the UK.

BACKGROUND: Equine dysautonomia or equine grass sickness (EGS), as it is more commonly known, is a usually fatal disease of equids of uncertain etiology, although associated with grazing, that affects the autonomic and enteric nervous system. Lowered gastrointestinal motility, leading to paralysis of the gut, is one of the main symptoms of EGS. Previous studies have implicated anaerobic bacteria, notably Clostridium botulinum, but what triggers the severe bacterial infestations remains enigmatic. We hypothesized that a detailed comparison of soil mineral and botanical composition of EGS and control sites would yield new insights into the causation of the disease. RESULTS: Between March 2007 and September 2008, soil, plant, and water samples from a total of 23 EGS sites and 11 control sites were studied. Metal and non-metal element levels of the soil and herbage samples were assessed. Significantly, EGS sites had higher levels of soil nitrogen, and significantly higher levels of iron, lead, arsenic, and chromium in the herbage. Toxic Ranunculus spp. (buttercups) were found in abundance at every EGS site, making ingestion plausible. Conversely, neurotoxin-producing cyanobacteria were not found in any of the water samples analyzed. CONCLUSIONS: The significantly higher levels of iron and heavy metals found in herbage growing in EGS sites, in addition to toxic Ranunculus species, suggest that previously unknown triggers are involved in a multi-factorial EGS etiology. Our results also show that cyanobacteria on the other hand, are unlikely to be a factor in EGS. Consequently, the concomitant presence of two (or more) factors could be the trigger for an outbreak of EGS.