Novel thiazolopyridine derivatives of diflapolin as dual sEH/FLAP inhibitors with improved solubility.

Inflammatory responses are orchestrated by a plethora of lipid mediators, and perturbations of their biosynthesis or degradation hinder resolution and lead to uncontrolled inflammation, which contributes to diverse pathologies. Small molecules that induce a switch from pro-inflammatory to anti-inflammatory lipid mediators are considered valuable for the treatment of chronic inflammatory diseases. Commonly used non-steroidal anti-inflammatory drugs (NSAIDs) are afflicted with side effects caused by the inhibition of beneficial prostanoid formation and redirection of arachidonic acid (AA) into alternative pathways. Multi-target inhibitors like diflapolin, the first dual inhibitor of soluble epoxide hydrolase (sEH) and 5-lipoxygenase-activating protein (FLAP), promise improved efficacy and safety but are confronted by poor solubility and bioavailability. Four series of derivatives bearing isomeric thiazolopyridines as bioisosteric replacement of the benzothiazole core and two series additionally containing mono- or diaza-isosteres of the phenylene spacer were designed and synthesized to improve solubility. The combination of thiazolo[5,4-b]pyridine, a pyridinylen spacer and a 3,5-Cl2-substituted terminal phenyl ring (46a) enhances solubility and FLAP antagonism, while preserving sEH inhibition. Moreover, the thiazolo[4,5-c]pyridine derivative 41b, although being a less potent sEH/FLAP inhibitor, additionally decreases thromboxane production in activated human peripheral blood mononuclear cells. We conclude that the introduction of nitrogen, depending on the position, not only enhances solubility and FLAP antagonism (46a), but also represents a valid strategy to expand the scope of application towards inhibition of thromboxane biosynthesis.

Phytochemical Characterization of Cannabis sativa L. Chemotype V Reveals Three New Dihydrophenanthrenoids That Favorably Reprogram Lipid Mediator Biosynthesis in Macrophages.

The growing general interest surrounding Cannabis sativa L. has led to a renewal in breeding and resulted in an impressive variability of chemotypical characteristics that required the division of cannabis into different recognized chemotypes. The chemotype V has been overlooked in terms of phytochemical composition due to the almost total absence of cannabinoids, on which biomedical attention is focused. Systematic approaches addressing diverse chemotypes are, however, needed to discriminate and define phytochemical aspects beyond cannabinoids. Such thoroughly characterized chemotypes guarantee blinding in controlled studies by mimicking the sensory properties of hemp and may help to unravel the "entourage effect". Capitalizing on the ability of cannabis to synthesize a large number of non-cannabinoid phenolic compounds, we here investigated, for the first time, the composition of the Ermo chemotype V and identified new compounds: two dihydrophenanthrenes and the methoxy-dihydrodenbinobin. All three compounds suppress pro-inflammatory leukotriene biosynthesis in activated macrophage subtypes by targeting 5-lipoxygenase, but substantially differ in their capacity to elevate the levels of specialized pro-resolving lipid mediators and their precursors in M2 macrophages. We conclude that the discovered compounds likely contribute to the anti-inflammatory properties of Cannabis sativa L. chemotype V and might promote inflammation resolution by promoting a lipid mediator class switch.

Rotational constriction of curcuminoids impacts 5-lipoxygenase and mPGES-1 inhibition and evokes a lipid mediator class switch in macrophages.

Polypharmacological targeting of lipid mediator networks offers potential for efficient and safe anti-inflammatory therapy. Because of the diversity of its biological targets, curcumin (1a) has been viewed as a privileged structure for bioactivity or, alternatively, as a pan-assay interference (PAIN) compound. Curcumin has actually few high-affinity targets, the most remarkable ones being 5-lipoxygenase (5-LOX) and microsomal prostaglandin E2 synthase (mPGES)-1. These enzymes are critical for the production of pro-inflammatory leukotrienes and prostaglandin (PG)E2, and previous structure-activity-relationship studies in this area have focused on the enolized 1,3-diketone motif, the alkyl-linker and the aryl-moieties, neglecting the rotational state of curcumin, which can adopt twisted conformations in solution and at target sites. To explore how the conformation of curcuminoids impacts 5-LOX and mPGES-1 inhibition, we have synthesized rotationally constrained analogues of the natural product and its pyrazole analogue by alkylation of the linker and/or of the ortho aromatic position(s). These modifications strongly impacted 5-LOX and mPGES-1 inhibition and their systematic analysis led to the identification of potent and selective 5-LOX (3b, IC50 = 0.038 µM, 44.7-fold selectivity over mPGES-1) and mPGES-1 inhibitors (2f, IC50 = 0.11 µM, 4.6-fold selectivity over 5-LOX). Molecular docking experiments suggest that the C2-methylated pyrazolocurcuminoid 3b targets an allosteric binding site at the interface between catalytic and regulatory 5-LOX domain, while the o, o'-dimethylated desmethoxycurcumin 2f likely binds between two monomers of the trimeric mPGES-1 structure. Both compounds trigger a lipid mediator class switch from pro-inflammatory leukotrienes to PG and specialized pro-resolving lipid mediators in activated human macrophages.

PI(18:1/18:1) is a SCD1-derived lipokine that limits stress signaling.

Cytotoxic stress activates stress-activated kinases, initiates adaptive mechanisms, including the unfolded protein response (UPR) and autophagy, and induces programmed cell death. Fatty acid unsaturation, controlled by stearoyl-CoA desaturase (SCD)1, prevents cytotoxic stress but the mechanisms are diffuse. Here, we show that 1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol) [PI(18:1/18:1)] is a SCD1-derived signaling lipid, which inhibits p38 mitogen-activated protein kinase activation, counteracts UPR, endoplasmic reticulum-associated protein degradation, and apoptosis, regulates autophagy, and maintains cell morphology and proliferation. SCD1 expression and the cellular PI(18:1/18:1) proportion decrease during the onset of cell death, thereby repressing protein phosphatase 2 A and enhancing stress signaling. This counter-regulation applies to mechanistically diverse death-inducing conditions and is found in multiple human and mouse cell lines and tissues of Scd1-defective mice. PI(18:1/18:1) ratios reflect stress tolerance in tumorigenesis, chemoresistance, infection, high-fat diet, and immune aging. Together, PI(18:1/18:1) is a lipokine that links fatty acid unsaturation with stress responses, and its depletion evokes stress signaling.