l-663536 and Peritonitis

The anticarcinogenic and anti-inflammatory properties of curcumin have been extensively investigated, identifying prostaglandin E2 synthase (mPGES)-1 and 5-lipoxygenase (5-LO), key enzymes linking inflammation with cancer, as high affinity targets. A comparative structure-activity study revealed three modifications dissecting mPGES-1/5-LO inhibition, namely (i) truncation of the acidic, enolized dicarbonyl moiety and/or replacement by pyrazole, (ii) hydrogenation of the interaryl linker, and (iii) (dihydro)prenylation. The prenylated pyrazole analogue 11 selectively inhibited 5-LO, outperforming curcumin by a factor of up to 50, and impaired zymosan-induced mouse peritonitis along with reduced 5-LO product levels. Other pro-inflammatory targets of curcumin (i.e., mPGES-1, cyclooxygenases, 12/15-LOs, nuclear factor-κB, nuclear factor-erythroid 2-related factor-2, and signal transducer and activator of transcription 3) were hardly affected by 11. The strict structural requirements for mPGES-1 and 5-LO inhibition strongly suggest that specific interactions rather than redox or membrane effects underlie the inhibition of mPGES-1 and 5-LO by curcumin.

Topics: Animals; Anti-Inflammatory Agents; Arachidonate 5-Lipoxygenase; Curcumin; Humans; Lipoxygenase Inhibitors; Male; Mice; Monocytes; Peritonitis; Structure-Activity Relationship

Dual inhibition of microsomal prostaglandin E2 synthase-1 (mPGES-1) and 5-lipoxygenase (5-LO) is currently pursued as potential pharmacological strategy for treatment of inflammation and cancer. Here we present a series of 26 novel 2-aminothiazole-featured pirinixic acid derivatives as dual 5-LO/mPGES-1 inhibitors with improved potency (exemplified by compound 16 (2-[(4-chloro-6-{[4-(naphthalen-2-yl)-1,3-thiazol-2-yl]amino}pyrimidin-2-yl)sulfanyl]octanoic acid) with IC50 = 0.3 and 0.4 μM, respectively) and bioactivity in vivo. Computational analysis presumes binding sites of 16 at the tip of the 5-LO catalytic domain and within a subpocket of the mPGES-1 active site. Compound 16 (10 μM) hardly suppressed cyclooxygenase (COX)-1/2 activities, failed to inhibit 12/15-LOs, and is devoid of radical scavenger properties. Finally, compound 16 reduced vascular permeability and inflammatory cell infiltration in a zymosan-induced mouse peritonitis model accompanied by impaired levels of cysteinyl-leukotrienes and prostaglandin E2. Together, 2-aminothiazole-featured pirinixic acids represent potent dual 5-LO/mPGES-1 inhibitors with an attractive pharmacological profile as anti-inflammatory drugs.

Topics: Animals; Arachidonate 5-Lipoxygenase; Binding Sites; Drug Design; Humans; Hydrophobic and Hydrophilic Interactions; Inhibitory Concentration 50; Intramolecular Oxidoreductases; Lipoxygenase Inhibitors; Male; Mice; Microsomes; Models, Molecular; Peritonitis; Prostaglandin-E Synthases; Protein Conformation; Pyrimidines; Structure-Activity Relationship; Thiazoles; Zymosan

The initial phase of zymosan-induced peritonitis involves an increase of vascular permeability (peak at 30 min) that is correlated with high levels of vasoactive eicosanoids, namely, prostaglandins (PGI2 and PGE2) of cyclooxygenase-1 origin (as estimated by RT-PCR) and cysteinyl-leukotrienes. Previously, we showed that the increase of vascular permeability can be attributed only partially to mast cells and their histamine, as seen in mast cell-deficient WBB6F1-W/Wv mice. Thus we aimed to identify the major cellular source(s) that mediate vasopermeability, as well as particular vasoactive mediators operating in this model. For this purpose, some mice were selectively depleted of either peritoneal macrophages or mast cells, and/or they were treated with several pharmacologic inhibitors of cyclooxygenase- and lipoxygenase-metabolic pathways. More-over, macrophage-depleted mast cell-deficient WBB6F1-W/Wv mice and their controls (+/+) were used. The macrophage depletion always caused a profound decrease of both vascular permeability and lipid-mediator levels, which was particularly pronounced for leukotrienes, whereas the effects of mast-cell depletion were less severe. The macrophage/mast-cell co-mediation of vasopermeability was also revealed in thioglycolate-induced peritonitis, as well as the macrophage origin of cysteinyl-leukotrienes. Taken together, these findings demonstrate that the resident peritoneal macrophages are in fact the main contributors to the vasopermeability at the early stages of zymosan-induced peritonitis.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Capillary Leak Syndrome; Capillary Permeability; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Cysteine; Diterpenes; Eicosanoids; Enzyme Induction; Ginkgolides; Histamine Release; Indoles; Indomethacin; Isoenzymes; Lactones; Leukotriene C4; Leukotrienes; Lipoxygenase Inhibitors; Macrophages, Peritoneal; Male; Mast Cells; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Mutant Strains; Nitrobenzenes; Peritonitis; Phospholipid Ethers; Platelet Activating Factor; Prostaglandin-Endoperoxide Synthases; Quinolines; Sulfonamides; Thioglycolates; Zymosan