The enzymes that catalyze the oxidative metabolism of arachidonic acid have provided fertile ground for the development of useful therapeutic agents for nearly a quarter century. Inhibitors of the ...enzyme cyclooxygenase prevent the formation of the prostaglandins and thromboxanes and are clinically useful antiinflammatories and peripheral analgesics. More recently it has been discovered that the enzyme 5-lipoxygenase is the first step in the formation of a series of biologically important metabolites of arachidonic acid, the leukotrienes. Evidence suggests that an inhibitor of 5-lipoxygenase may be a useful therapeutic agent in the treatment of asthma, immediate hypersensitivity, and inflammation. Various antioxidants have been examined as inhibitors of 5-lipoxygenase in vitro. We were intrigued by recent reports that the 2,3-dihydro-5-benzofuranol ring system maximizes the stereoelectronic effects necessary for efficient hydrogen atom abstraction by peroxyl radicals. In this study we describe the synthesis of over 50 new 2,3-dihydro-5-benzofuranols and their biological evaluation as inhibitors of leukotriene biosynthesis in isolated human polymorphonuclear leukocytes. We show that the 2,3-dihydro-5-benzofuranol ring system, although not a potent inhibitor of leukotriene biosynthesis in itself, can provide a useful template for the design of antioxidant-based inhibitors of leukotriene biosynthesis. Furthermore, within a structural class the potency of a given analogue can be predicted on the basis of its overall calculated lipophilicity (log P). The data are interpreted in terms of a model in which the observed inhibition by this class of inhibitors is dependent on the intrinsic ability of the antioxidant to reduce the enzyme and on the fraction of the inhibitor that is partitioned into the membrane.
Compound
28 was found to have a dissociated glucocorticoid profile in vitro and produced a dose-dependent anti-inflammatory response in an in vivo mouse model.
A novel series of selective ligands for ...the human glucocorticoid receptor is described. Structure–activity studies focused on variation of B-ring size, ketal ring size, and ketal substitution. These analogs were found to be potent and selective ligands for GR and have partial agonist profiles in functional assays for transactivation (TAT, GS) and transrepression (IL-6). Of these compounds,
27,
28, and
35 were evaluated further in a mouse LPS-induced TNF-α secretion model. Compound
28 had an ED
50 of 14.1
mg/kg compared with 0.5
mg/kg for prednisolone in the same assay.
The use of chronic glucocorticoid (GC) therapy for the treatment of inflammatory diseases is limited by associated metabolic side effects, including muscle atrophy. Therefore, selective ...glucocorticoid receptor-(GR)-binding ligands that maintain anti-inflammatory activity and demonstrate diminished side-effect profiles would have great therapeutic utility. In this work, we use Taqman PCR and ELISA methods to show that GCs can inhibit basal, and lipopolysaccharide (LPS)-stimulated levels of cytokines IL-6 and TNFα, and also the chemokine MCP-1 in a non-inflammatory system such as primary human skeletal muscle cells. In the murine C2C12 skeletal muscle cell line we observe a similar effect of GCs on IL-6 and MCP-1; however, in contrast to previous reports, we observe a time-dependent repression of TNFα. Furthermore, in skeletal muscle cells, concomitant with cytokine repression, GCs transcriptionally induce glutamine synthetase (GS), a marker for muscle wasting, in an LPS independent manner. Similarly, administration of dexamethasone to mice, previously administered LPS, results in an increase in GS and an inhibition of TNFα and MCP-1 in skeletal muscle tissue. Thus, skeletal muscle cells and tissues present a novel system for the identification of selective GR-binding ligands, which simultaneously inhibit cytokine expression in the absence of GS induction.
The synthesis and nitric oxide synthase inhibitory activity of bicyclic amidines are described. The 6,6 and 5,6 fused amidines
8a and
10a are potent, selective, and orally active iNOS inhibitors.
...Syntheses and nitric oxide synthase inhibitory activity of cyclic amidines containing 5,6- 6,6- and 7,6-fused systems are described. X-ray structure determination facilitated the assignment of the stereochemistry of the most active compounds perhydro-2-iminoisoquinoline (
8a) and perhydro-2-iminopyrindine (
10a). Both
8a and
10a are very potent inhibitors of iNOS, with excellent selectivity over eNOS and they are orally active in rats with long duration suitable for once or twice a day dosing.
GPR109A is the receptor mediating both the antilipolytic and vasodilatory effects of nicotinic acid. In order to develop agonists for GPR109A with improved therapeutic indices we have sought to ...optimize animal models that evaluate both nicotinic acid-mediated inhibition of lipolysis and stimulation of vasodilatation. The rat and the dog have previously been used to study the antilipolytic effects of nicotinic acid, but no optimal vasodilatation model exits in either species.
We have developed a vasodilatation model in the rat that measures changes in ear perfusion using laser Doppler flowmetry. In the dog, we have developed a model of vasodilatation measuring changes in red color values in the ear, using a spectrocolorimeter. Effects of GPR109A agonists on lipolysis were measured in both species after oral dosing of compounds, and measuring plasma levels of free fatty acids.
In both rat and dog, GPR109A agonists induce dose- and time-dependent vasodilatation, similar to that observed in humans. Vasodilatation is inhibited in both species with cyclooxygenase inhibitors or a specific DP1 receptor antagonist, indicating that, as in man, nicotinic acid-induced vasodilatation in rats and dogs is mainly mediated by the release of PGD
2.
Our results show that both rat and dog are useful models for the characterization of GPR109A agonists. A therapeutic index for GPR109A agonists can be calculated in either species.
Injection of brewer's yeast into the rat paw results in edema and a subsequent hyperalgesia. The edema was accompanied by an increase in 5-lipoxygenase products, and the hyperalgesia coincided with ...the formation of both cyclooxygenase and 5-lipoxygenase products. When administered perorally, indomethacin inhibited cyclooxygenase product formation, phenidone inhibited 5-lipoxygenase product formation, and 3-amino-1-(m-trifluoromethyl-phenyl)-2-pyrazoline (BW 755C) inhibited formation of products of both pathways. These compounds were also effective analgesic agents. The correlation of these effects with the suppression of hyperalgesia suggests the participation of products from both cyclooxygenase and 5-lipoxygenase pathways in the mediation of hyperalgesia.
A series of betamethasone 17alpha-carbamates were designed, synthesized, and evaluated for their ability to dissociate the two main functions of the glucocorticoid receptor, that is, transactivation ...and transrepression, in rat cell lines. A number of alkyl substituted betamethasone 17alpha-carbamates were identified with excellent affinity for the glucocorticoid receptor (e.g., 7, GR IC(50) 5.1 nM) and indicated dissociated profiles in functional assays of transactivation (rat tyrosine aminotransferase, TAT, and rat glutamine synthetase, GS) and transrepression (human A549 cells, MMP-1 assay). Gratifyingly, the in-vivo profile of these compounds, for example, 7, also indicated potent anti-inflammatory activity with impaired effects on glucose, insulin, triglycerides, and body weight. Taken together, these results indicate that dissociated glucocorticoid receptor modulators can be identified in rodents.
An indole class of leukotriene synthesis inhibitors, exemplified by MK-886, which does not directly inhibit 5-lipoxygenase,
has been shown to bind to an 18-kDa leukocyte membrane protein and to ...inhibit 5-lipoxygenase membrane translocation. It was
demonstrated that the 18-kDa protein is necessary for the cellular activation of leukotriene synthesis and was named 5-lipoxygenase-activating
protein (FLAP). We describe here a class of leukotriene synthesis inhibitors based on a quinoline structure, which is structurally
distinct from MK-886. However, similar to MK-886, several quinolines are potent inhibitors of cellular leukotriene synthesis
but are poor inhibitors of soluble 5-lipoxygenase. To determine whether FLAP is the protein target of leukotriene synthesis
inhibitors of the quinoline class, we investigated the ability of these compounds to inhibit photoaffinity labeling of FLAP
and to elute FLAP from indole affinity gels. The abilities of the quinoline inhibitors to interact with FLAP correlated well
with their abilities to inhibit leukotriene synthesis in human polymorphonuclear leukocytes. L-674,573, a potent quinoline
leukotriene synthesis inhibitor, inhibited indole photoaffinity labeling of FLAP in a concentration-dependent manner. In addition,
L-674,573 selectively eluted FLAP from indole affinity gels, in contrast to L-671,480, a quinoline that was inactive as an
inhibitor of leukotriene synthesis. When human leukocyte membranes were labeled with the indole photoaffinity probe 125IL-669,083
and immunoprecipitated with a FLAP antibody, the labeling of FLAP was inhibited by L-674,573 but not by L-671,480. These results
suggest a direct binding site for the quinoline leukotriene synthesis inhibitors on FLAP and provide further evidence for
the essential role of FLAP in cellular leukotriene synthesis.
The leukotrienes, metabolites of arachidonic acid produced through the action of the enzyme 5-lipoxygenase, are important mediators of immediate hypersensitivity and inflammation. Among the variety ...of diseases in which the leukotrienes may play a symptomatic or causative role is the dermatological condition psoriasis, a chronic proliferative disease of the skin. This study reports the synthesis and comparative biological activities of various ortho-substituted phenols including 4-methoxyphenols, 6-hydroxy-1,2,3,4-tetrahydrobenzopyrans, 2,3-dihydro-5-benzofuranols, and 5-benzofuranols. The phenols prepared in this study were evaluated for their ability to inhibit the production of leukotriene B4(LTB4) in isolated human polymorphonuclear leukocytes (PMNs) and to inhibit a topical inflammatory response in the topical mouse ear (TME) model. In the former case, when the log IC50 was plotted versus the log of the octanol/water partition coefficient (log P), to eliminate the effect of lipophilicity, the 2,3-dihydro-5-benzofuranol ring system was shown to be more potent than the other ring systems examined throughout the range of partition coefficients studied. The ability to inhibit leukotriene production in vitro in human PMNs can be rationalized on the basis of a model that suggests that the observed inhibition is dependent on the kinetic ability of the inhibitor to reduce a radical species and on the fraction of inhibitor that is partitioned into the cell membrane. While the in vivo antiinflammatory activity as measured by the TME did not correlate with the in vitro data, it was felt that the TME represented a valuable measure of the ability of a compound to penetrate the skin to the site of an ongoing inflammatory response. Of the compounds synthesized in this study, 6-1-2-(hydroxymethyl)phenyl-1-propen-3-yl-2,3-dihydro-5-benzof uranol (1, L-651896) was chosen for further development.
