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Pathological forms of Tau protein are directly associated with neurodegeneration and correlate with Alzheimer's Disease (AD) symptoms, progression, and severity. Previously, using various mouse models of Tauopathies and AD, we have demonstrated the immunogenicity and efficacy of the MultiTEP-based adjuvanted vaccine targeting the phosphatase activating domain (PAD) of Tau, AV-1980R/A. Here, we analyzed its immunogenicity in non-human primates (NHP), the closest phylogenic relatives to humans with a similar immune system, to initiate the transition of this vaccine into clinical trials. We have demonstrated that AV-1980R/A is highly immunogenic in these NHPs, activating a broad but unique to each monkey repertoire of MultiTEP-specific T helper (Th) cells that, in turn, activate B cells specific to PAD. The resulting anti-PAD IgG antibodies recognize pathological Tau tangles and Tau-positive neuritis in AD case brain sections with no staining in control non-AD cases. These published data and efficacy results support the AV-1980R/A vaccine progression to first-in-human clinical trials., (© 2022. The Author(s).)

BMS-813160 (compound 3 ) was identified as a potent and selective CCR2/5 dual antagonist. Compound 3 displayed good permeability at pH = 7.4 in PAMPA experiments and demonstrated excellent human liver microsome stability. Pharmacokinetic studies established that 3 had excellent oral bioavailability and exhibited low clearance in dog and cyno. Compound 3 was also studied in the mouse thioglycollate-induced peritonitis model, which confirmed its ability to inhibit the migration of inflammatory monocytes and macrophages. As a result of this profile, compound 3 was selected as a clinical candidate., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

To improve the metabolic stability profile of BMS-741672 ( 1a ), we undertook a structure-activity relationship study in our trisubstituted cyclohexylamine series. This ultimately led to the identification of 2d (BMS-753426) as a potent and orally bioavailable antagonist of CCR2. Compared to previous clinical candidate 1a , the tert -butyl amine 2d showed significant improvements in pharmacokinetic properties, with lower clearance and higher oral bioavailability. Furthermore, compound 2d exhibited improved affinity for CCR5 and good activity in models of both monocyte migration and multiple sclerosis in the hCCR2 knock-in mouse. The synthesis of 2d was facilitated by the development of a simplified approach to key intermediate (4 R )- 9b that deployed a stereoselective reductive amination which may prove to be of general interest., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

Structure-activity relationship studies directed toward the replacement of the fused phenyl ring of the lead hexahydrobenzoindole RORγt inverse agonist series represented by 1 with heterocyclic moieties led to the identification of three novel aza analogs 5 - 7 . The hexahydropyrrolo[3,2- f ]quinoline series 5 (X = N, Y = Z=CH) showed potency and metabolic stability comparable to series 1 but with improved in vitro membrane permeability and serum free fraction. This structural modification was applied to the hexahydrocyclopentanaphthalene series 3 , culminating in the discovery of 8e as a potent and selective RORγt inverse agonist with an excellent in vitro profile, good pharmacokinetic properties, and biologic-like in vivo efficacy in preclinical models of rheumatoid arthritis and psoriasis., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

Employing a virtual screening approach, we identified the pyroglutamide moiety as a nonacid replacement for the cyclohexanecarboxylic acid group which, when coupled to our previously reported conformationally locked tricyclic core, provided potent and selective RORγt inverse agonists. Structure-activity relationship optimization of the pyroglutamide moiety led to the identification of compound 18 as a potent and selective RORγt inverse agonist, albeit with poor aqueous solubility. We took advantage of the tertiary carbinol group in 18 to synthesize a phosphate prodrug, which provided good solubility, excellent exposures in mouse PK studies, and significant efficacy in a mouse model of psoriasis., Competing Interests: The authors declare no competing financial interest., (© 2020 American Chemical Society.)

Novel tricyclic analogues were designed, synthesized, and evaluated as RORγt inverse agonists. Several of these compounds were potent in an IL-17 human whole blood assay and exhibited excellent oral bioavailability in mouse pharmacokinetic studies. This led to the identification of compound 5 , which displayed dose-dependent inhibition of IL-17F production in a mouse IL-2/IL-23 stimulated pharmacodynamic model. In addition, compound 5 was studied in mouse acanthosis and imiquimod-induced models of skin inflammation, where it demonstrated robust efficacy comparable to a positive control. As a result of this excellent overall profile, compound 5 (BMS-986251) was selected as a clinically viable developmental candidate., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

RORγt is an important nuclear receptor that regulates the production of several pro-inflammatory cytokines such as IL-17 and IL-22. As a result, RORγt has been identified as a potential target for the treatment of various immunological disorders such as psoriasis, psoriatic arthritis, and inflammatory bowel diseases. Structure and computer-assisted drug design led to the identification of a novel series of tricyclic RORγt inverse agonists with significantly improved in vitro activity in the reporter (Gal4) and human whole blood assays compared to our previous chemotype. Through careful structure activity relationship, several potent and selective RORγt inverse agonists have been identified. Pharmacokinetic studies allowed the identification of the lead molecule 32 with a low peak-to-trough ratio. This molecule showed excellent activity in an IL-2/IL-23-induced mouse pharmacodynamic study and demonstrated biologic-like efficacy in an IL-23-induced preclinical model of psoriasis.

Bruton's tyrosine kinase (BTK), a non-receptor tyrosine kinase, is a member of the Tec family of kinases and is essential for B cell receptor (BCR) mediated signaling. BTK also plays a critical role in the downstream signaling pathways for the Fcγ receptor in monocytes, the Fcε receptor in granulocytes, and the RANK receptor in osteoclasts. As a result, pharmacological inhibition of BTK is anticipated to provide an effective strategy for the clinical treatment of autoimmune diseases such as rheumatoid arthritis and lupus. This article will outline the evolution of our strategy to identify a covalent, irreversible inhibitor of BTK that has the intrinsic potency, selectivity, and pharmacokinetic properties necessary to provide a rapid rate of inactivation systemically following a very low dose. With excellent in vivo efficacy and a very desirable tolerability profile, 5a (branebrutinib, BMS-986195) has advanced into clinical studies.

We encountered a dilemma in the course of studying a series of antagonists of the G-protein coupled receptor CC chemokine receptor-2 (CCR2): compounds with polar C3 side chains exhibited good ion channel selectivity but poor oral bioavailability, whereas compounds with lipophilic C3 side chains exhibited good oral bioavailability in preclinical species but poor ion channel selectivity. Attempts to solve this through the direct modulation of physicochemical properties failed. However, the installation of a protonation-dependent conformational switching mechanism resolved the problem because it enabled a highly selective and relatively polar molecule to access a small population of a conformer with lower polar surface area and higher membrane permeability. Optimization of the overall properties in this series yielded the CCR2 antagonist BMS-741672 ( 7 ), which embodied properties suitable for study in human clinical trials., Competing Interests: The authors declare no competing financial interest.

Incorporation of a suitably-placed electrophilic group transformed a series of reversible BTK inhibitors based on carbazole-1-carboxamide and tetrahydrocarbazole-1-carboxamide into potent, irreversible inhibitors. Removal of one ring from the core of these compounds provided a potent irreversible series of 2,3-dimethylindole-7-carboxamides having excellent potency and improved selectivity, with the additional advantages of reduced lipophilicity and molecular weight., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

PI3Kδ plays an important role controlling immune cell function and has therefore been identified as a potential target for the treatment of immunological disorders. This article highlights our work toward the identification of a potent, selective, and efficacious PI3Kδ inhibitor. Through careful SAR, the successful replacement of a polar pyrazole group by a simple chloro or trifluoromethyl group led to improved Caco-2 permeability, reduced Caco-2 efflux, reduced hERG PC activity, and increased selectivity profile while maintaining potency in the CD69 hWB assay. The optimization of the aryl substitution then identified a 4'-CN group that improved the human/rodent correlation in microsomal metabolic stability. Our lead molecule is very potent in PK/PD assays and highly efficacious in a mouse collagen-induced arthritis model.

Bruton's tyrosine kinase (BTK), a nonreceptor tyrosine kinase, is a member of the Tec family of kinases. BTK plays an essential role in B cell receptor (BCR)-mediated signaling as well as Fcγ receptor signaling in monocytes and Fcε receptor signaling in mast cells and basophils, all of which have been implicated in the pathophysiology of autoimmune disease. As a result, inhibition of BTK is anticipated to provide an effective strategy for the clinical treatment of autoimmune diseases such as lupus and rheumatoid arthritis. This article details the structure-activity relationships (SAR) leading to a novel series of highly potent and selective carbazole and tetrahydrocarbazole based, reversible inhibitors of BTK. Of particular interest is that two atropisomeric centers were rotationally locked to provide a single, stable atropisomer, resulting in enhanced potency and selectivity as well as a reduction in safety liabilities. With significantly enhanced potency and selectivity, excellent in vivo properties and efficacy, and a very desirable tolerability and safety profile, 14f (BMS-986142) was advanced into clinical studies.

Bruton's tyrosine kinase (BTK) belongs to the TEC family of nonreceptor tyrosine kinases and plays a critical role in multiple cell types responsible for numerous autoimmune diseases. This article will detail the structure-activity relationships (SARs) leading to a novel second generation series of potent and selective reversible carbazole inhibitors of BTK. With an excellent pharmacokinetic profile as well as demonstrated in vivo activity and an acceptable safety profile, 7-(2-hydroxypropan-2-yl)-4-[2-methyl-3-(4-oxo-3,4-dihydroquinazolin-3-yl)phenyl]-9H-carbazole-1-carboxamide 6 (BMS-935177) was selected to advance into clinical development.

A novel cyclohexenyl series of CCR2 antagonists has been discovered. This series of small, rigid compounds exhibits submicromolar binding affinity for CCR2. Modification of the substituents on the cyclohexene ring led to the identification of potent CCR2 antagonists. Progress from initial lead 5 (IC50=700nM) to (-)-38 (IC50=9.0nM) is discussed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Four series of disubstituted carbazole-1-carboxamides were designed and synthesised as inhibitors of Bruton's tyrosine kinase (BTK). 4,7- and 4,6-disubstituted carbazole-1-carboxamides were potent and selective inhibitors of BTK, while 3,7- and 3,6-disubstituted carbazole-1-carboxamides were potent and selective inhibitors of Janus kinase 2 (JAK2)., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

We describe the hybridization of our previously reported acyclic and cyclic CC chemokine receptor 2 (CCR2) antagonists to lead to a new series of dual antagonists of CCR2 and CCR5. Installation of a γ-lactam as the spacer group and a quinazoline as a benzamide mimetic improved oral bioavailability markedly. These efforts led to the identification of 13d, a potent and orally bioavailable dual antagonist suitable for use in both murine and monkey models of inflammation.

Conformational analysis of the 3-benzylpiperidine in CCR3 antagonist clinical candidate 1 (BMS-639623) predicts that the benzylpiperidine may be replaced by acyclic, conformationally stabilized, anti-1,2-disubstituted phenethyl- and phenpropylamines. Ab initio calculations, enantioselective syntheses, and evaluation in CCR3 binding and chemotaxis assays of anti-1-methyl-2-hydroxyphenethyl- and phenpropylamine-containing CCR3 antagonists support this conformational correlation.

DPC168, a benzylpiperidine-substituted aryl urea CCR3 antagonist evaluated in clinical trials, was a relatively potent inhibitor of the 2D6 isoform of cytochrome P-450 (CYP2D6). Replacement of the cyclohexyl central ring with saturated heterocycles provided potent CCR3 antagonists with improved selectivity against CYP2D6. The favorable preclinical profile of DPC168 was maintained in an acetylpiperidine derivative, BMS-570520.

The synthesis and structure-activity relationships of N-arylalkylpiperidylmethyl ureas as antagonists of the CC chemokine receptor-3 (CCR3) are presented. These compounds displayed potent binding to the receptor as well as functional antagonism of eotaxin-elicited effects on eosinophils.

Structural features of a 5-amidinoindole inhibitor of factor Xa, which displayed modest inhibition of factor IXa were varied to increase potency and improve selectivity for factor IXa.

Increased density of proliferating and migrating tumor cells and neovascular endothelial cells has been associated with tumor progression and poor prognosis in patients with squamous cell carcinoma (SCC). Tumor and neovascular endothelial cells in squamous cell carcinoma have been reported to express integrin heterodimers containing the alphav subunit, which binds to vitronectin and other extracellular matrix proteins that contain the amino acid recognition sequence Arg-Gly-Asp (RGD). In the present study, we examined the effect of the novel non-peptide alphav integrin antagonist SM256 on growth of SCC line PAM LY8 in BALB/c SCID mice, and determined whether SM256 has direct inhibitory effects on growth of murine endothelial and PAM LY8 SCC cells in vitro. SM256 inhibits cell adhesion of murine cells expressing alphavbeta3 and alphavbeta5 integrins in vitro with an IC50 of 35 nM and 30 nM, respectively. Growth of Pam LY8 tumors in vivo was inhibited with 14-day continuous administration of SM256 by subcutaneous osmotic diffusion pump, during which a mean serum concentration of 56 nM was detected. While both murine aortic endothelial cells and PAM LY8 were found to express alphav integrins by fluorescence cytofluorometry, SM256 at 50 nM in MTT assay completely inhibited growth of endothelial cells, but had no significant direct effect on growth of PAM LY8 cells. We compared the effect on growth of PAM LY8 of SM256 infusion versus single agent or combination chemotherapy with a maximally tolerated dose of cis-platinum, which is used as a standard chemotherapy for SCC. When treatment was initiated at either 7 or 21 days following establishment of tumor, 14-day infusion of SM256 had an inhibitory effect on growth that was similar to that obtained with single dose cis-platinum, but no additive effect of concurrent therapy with SM256 and cis-platinum was observed. These results demonstrate the activity and feasibility of use of alphav antagonists such as SM256 for therapy of SCC.

A new series of indazole-containing alpha(v)beta(3) integrin antagonists is described. Starting with lead compound 18a, variations in a number of structural features were explored with respect to inhibition of the binding of beta(3)-transfected 293 cells to fibrinogen and to selectivity for alpha(v)beta(3) over GPIIbIIIa, another RGD-binding integrin. Indazoles attached to a 2-aminopyridine or 2-aminoimidazole by a propylene linker at the indazole 1-position and to a diaminopropionate derivative via a 5-carboxylate amide provided the best potency with moderate selectivity. Several differences in the SAR of the diaminopropionate moiety were observed between this series and a series of isoxazoline-based selective GPIIbIIIa antagonists. Compound 34a (SM256) was a potent antagonist of alpha(v)beta(3) (IC(50) 2.3 nM) with 9-fold selectivity over GPIIbIIIa.

Modification of the alpha-carbamate substituent of isoxazoline GPIIb/IIIa (alphaIIb beta3) antagonist DMP 754 (7) led to a series of alpha-sulfonamide and alpha-sulfamide diaminopropionate isoxazolinylacetamides which were found to be potent inhibitors of in vitro platelet aggregation. Aryl- and heteroaryl-alpha-sulfonamide groups, in conjunction with (5R)-isoxazoline (2S)-diaminopropionate stereochemistry, were found to impart a pronounced duration of antiplatelet effect in dogs, potentially due to high affinity for unactivated platelets. Isoxazolylsulfonamide 34b (DMP 802), a highly selective GPIIb/IIIa antagonist, demonstrated a prolonged duration of action after iv and po dosing and high affinity for resting and activated platelets. The prolonged antiplatelet profile of DMP 802 in dogs and the high affinity of DMP 802 for human platelets may be predictive of clinical utility as a once-daily antiplatelet agent.

Isoxazoline containing RGD mimetics were rapidly synthesized on a solid phase to optimize linkers, regioisomers of isoxazoline scaffolds, and exosite binding groups to yield lead alphavbeta3 antagonists.

The discovery of terphenyl derivatives as highly selective COX-2 inhibitors resulted from our efforts to overcome poor pharmacokinetics demonstrated by the COX-2 selective diarylthiophene DuP 697 [2-bromo-4-(4'-sulfonylmethyl)phenyl-5-(4'-fluoro)phenylthiophe ne]. Detailed SAR related to the ortho-biphenyls and variants of the central ring are described herein.

This study was undertaken to define the alphavbeta3 binding affinity and specificity of the low-molecular-weight nonpeptide integrin antagonist, SM256. SM256 demonstrated high potency (IC50, 0.057+/-0.030 nM) in inhibiting vitronectin binding to purified human alphavbeta3 receptors. Additionally, SM256 inhibited alphavbeta3-mediated human umbilical vein endothelial cell (HUVEC) or 293/beta3 (beta3-transfected cell line) adhesion to fibrinogen with IC50 values of 0.0054+/-0.0058 and 0.0023+/-0.0012 microM, respectively. SM256 demonstrated a relatively high degree of specificity for human alphavbeta3-mediated functions as compared with other human integrins including alphavbeta5 (IC50, 0.92+/-0.69 microM), alphaIIbbeta3 (IC50, 0.72+/-0.07 microM), alpha4/beta1 (IC50, >100 microM) and alpha5/beta1 (IC50, 2.3+/-2.1 microM). SM256 demonstrated different degree of species specificity in blocking alphavbeta3-mediated cellular adhesion with relatively higher affinity to dog (IC50, 0.005+/-0.002 microM), rabbit (IC50, 0.021+/-0.01 microM), mouse (IC50, 0.035+/-0.01 microM), and pig (IC50, 0.41+/-0.24 microM) endothelial or smooth-muscle cell alphavbeta3-mediated adhesion. Additionally, SM256 demonstrated high degree of alphavbeta3 specificity as compared with alphavbeta5, alpha5beta1, or alphaIIbbeta3-mediated binding in these species. SM256 is a potent alphavbeta3, antagonist with high affinity and specificity for alphavbeta3-mediated functions. Additionally, a comparable alphavbeta3 affinity for SM256 was demonstrated with endothelial cells obtained from various species (dog, mouse, rabbit, and pig) as compared with that from human.

Structure-activity relationships were explored for some analogs of Brequinar having a linking atom between the 2-biphenyl substituent and the quinoline ring. Activities as inhibitors of dihydroorotate dehydrogenase and the mixed lymphocyte reaction were related to the overall shape and lipophilicity of the 2-substituent.

The structure-activity relationships of some tetracyclic heterocycles related to Brequinar were explored. Activities as inhibitors of dihydroorotate dehydrogenase and the mixed lymphocyte reaction are related to ring system, heteroatom placement, and pendant ring substitution.

Using isoxazoline XR299 (1a) as a starting point for the design of highly potent, long-duration GPIIb/IIIa antagonists, the effect of placing lipophilic substituents at positions alpha and beta to the carboxylate moiety was evaluated. Of the compounds studied, it was found that the n-butyl carbamate 24u exhibited superior potency and duration of ex vivo antiplatelet effects in dogs. Replacement of the benzamidin-4-yl moiety with alternative basic groups, elimination of the isoxazoline stereocenter, and reversal of the orientation of the isoxazoline ring resulted in lowered potency and/or duration of action.

A series of 2-(arylmethyl)pyridoisothiazolones is reported that inhibit the IL-1 beta induced breakdown of bovine nasal septum cartilage in an organ culture assay. The synthesis and preliminary SAR of these compounds are described. These compounds represent a novel, non-peptide lead series approach to the mediation of the chronic cartilage breakdown associated with arthritic disease. These compounds are relatively resistant to reductive metabolism by liver microsomal preparations and appear to inhibit cartilage breakdown by interfering with the proteolytic activation of matrix metalloproteinases.

The synthesis, biological evaluation, and structure-activity relationships of a series of N-phenyl heteroaryl-fused isothiazolones are described. These isothiazolones have been shown to exhibit potent, dose-dependent inhibition of IL-1 beta-induced breakdown of proteoglycan in a cartilage organ culture assay. This effect is likely due to inhibition of MMP activation and a consequent reduction in MMP activity following IL-1 beta stimulation. Thus these compounds potentially represent simple, non-peptidic disease-modifying agents for the treatment of arthritic diseases. To examine the effects of structure on in vitro activity, three general features of the molecules were varied, substituents on the pendant N-phenyl group, the position of ring fusion to the isothiazolone, and substituents on the fused ring peri to the isothiazolone sulfur.

A series of 2'-substituted chalcone derivatives has been found to show potent inhibition of the production of IL-1 beta from human peripheral blood monocytes stimulated with lipopolysaccharide (LPS), with IC50 values in the 0.2-5.0-microM range. Some members of the series have also shown inhibition of septic shock induced in mice by injection of LPS, although with low potency. Qualitative structure-activity relationships have shown that the enone is required for activity, which may be mediated by conjugate addition of a biological nucleophile to the chalcone. Electron-poor aromatic rings beta to the ketone give enhanced potency. Although electronic effects in the other ring (directly attached to the ketone) are minimal, this ring must possess an ortho substituent for good activity without cytotoxicity, suggesting a degree of selectivity which would not be expected for simple, nonspecific alkylating agents.

The synthesis, biological evaluation, and structure-activity relationships of a series of 1-(pyridylphenyl)-1-phenyl-2-imidazolylethanols are described. These compounds show potent dose-dependent topical antiinflammatory activity in murine models of skin inflammation. This effect is likely due to inhibition of cytochrome P450 and consequent reduction in levels of 12R-HETE in the skin. These compounds were examined for their ability to inhibit the oxidative metabolism of arachidonic acid; they specifically inhibit the formation of prostacyclins in mouse macrophages. To study the effects of structure on the in vivo activity, three general features of the molecules were varied: the position of attachment of the pyridine nucleus (A), the second aromatic residue (B), and the nitrogen base on the ethanol chain (C). 1-[4-(4-Pyridyl)phenyl]-1-(4-fluorophenyl)-2- imidazolylethanol (2a, DuP 983) shows a very attractive profile of antiinflammatory activity and has been selected for clinical evaluation as a topical antiinflammatory agent.

DuP 654 (2-benzyl-1-naphthol) is a topically active anti-inflammatory agent that was evaluated in phase II clinical trials as an anti-psoriatic agent. The compound is a potent 5-lipoxygenase inhibitor and exhibits inhibitory activity against lipopolysaccharide-stimulated release of interleukin-1 from human monocytes. DuP 654 cannot be used as a systemic anti-inflammatory compound due to its rapid and extensive metabolism. Fifteen analogs were synthesized in an attempt to block the systemic route(s) of metabolism. The compounds were evaluated (IP and PO) in the rat carrageenan paw edema inflammation model with plasma samples taken at 1, 2, 3, and 4 hours post-dose. Substitutions at the 4- and/or 8-positions on the naphthol, and/or on the benzyl group of the DuP 654 molecule were unsuccessful in achieving an analog which displayed both oral activity in the inflammatory model and high plasma levels without manifesting toxicity. The low plasma levels of some analogs may indicate poor absorption, high volume of distribution, or that the substitution did not inhibit the high hepatic "first-pass" metabolism observed with DuP 654. Other compounds not studied but similar in structure to DuP 654 may exhibit rapid and extensive metabolism.

A wide variety of agents have been reported as 5-LO inhibitors. The majority of the series appear to be lipophilic reducing agents, including phenols, partially saturated aromatics, and compounds containing heteroatom-heteroatom bonds. Many of these are not selective 5-LO inhibitors, but often affect CO and other LOs as well. In vivo systemic activity for many of these has been, in general, disappointing, probably because of poor bioavailability caused by lipophilicity and metabolic instability (oxidation, and conjugation of phenolic compounds). However, topically a number of agents have shown promise for skin inflammation, with Syntex's lonapalene the most advanced of these. Most results published to date appear more disappointing in the allergy/asthma field. More excitingly, a few structural types are selective 5-LO inhibitors which have shown systemic activity in vivo and in the clinic. Abbott's zileuton (136) appears to be one of the leading compounds in this category, along with other hydroxamates such as BW-A4C (129) from Burroughs-Wellcome. Recent selective non-reducing agents such as Wyeth-Ayerst's Wy-50,295 (143) and the similar ICI compounds such as ICI 216800 (145) also hold promise. The enantiospecific effects of (106) and (145) are especially interesting for the design of new inhibitors. If compounds like these validate the hypothesis that inhibition of 5-LO will have a significant anti-inflammatory effect, a redoubling of effort throughout the industry to find second- and third-generation selective agents may be expected. Part of the difficulty in interpreting and comparing the 5-LO literature is the plethora of test methods and activity criteria. As pointed out in the introduction, inhibition of product release from cells, often stimulated with A23187, has commonly been used to demonstrate 5-LO inhibition. However, this type of assay cannot be assumed to be diagnostic for 5-LO inhibition. Only if specificity for 5-LO product generation and (ideally) activity in cell-free enzymes is also shown should mechanistic interpretations be made. Recently, a new class of compounds was found at Merck which inhibited LT biosynthesis without inhibiting 5-LO, but apparently by a novel, specific mechanism. L-655,240 (169) and L-663,536 (MK-886) (170) were both active in human ISN, with IC50 values in the low micromolar range. Both also orally inhibited GPB (< 1 mg/kg). MK-886 was effective in Ascaris-induced asthma in squirrel monkeys, in rat carrageenan pleurisy, in rat Arthus pleurisy, and (topically) in guinea-pig ear oedema induced by A23187.(ABSTRACT TRUNCATED AT 400 WORDS)

Lipoxygenases are non-heme iron dioxygenases that catalyze the oxygenation of polyunsaturated fatty acids. Using soybean lipoxygenase-1 as a model, we have shown that two classes of lipoxygenase inhibitors currently in development as potential antiinflammatory agents obtain a significant amount of their potency by reducing the lipoxygenase active-site iron from the active ferric state to the inactive ferrous state. It is not surprising that the members of the first of these classes, the 2-benzyl-1-naphthols, are reducing agents. The members of the second class, the N-alkyl-hydroxamic acids, were not anticipated to be sufficiently strong reducing agents to be oxidized by the lipoxygenase ferric center; that they are provides additional evidence for that iron having a high reduction potential. This brings to (at least) five the number of classes of lipoxygenase inhibitors that are capable of reducing the active-site ferric ion and suggests the generality of this approach in the rational design of lipoxygenase inhibitors.

The synthesis, biological evaluation, and structure-activity relationships of a series of 1-naphthols bearing carbon substituents at the 2-position are described. These compounds are potent inhibitors of the 5-lipoxygenase from RBL-1 cells and also inhibit bovine seminal vesicle cyclooxygenase. Structure-activity relationships for these two enzymes are different, implying specific enzyme inhibition rather than a nonspecific antioxidant effect. 2-(Aryl-methyl)-1-naphthols are among the most potent 5-lipoxygenase inhibitors reported (IC50 values generally 0.01-0.2 microM) and show excellent antiinflammatory potency in the mouse arachidonic acid ear edema model. To study the effects of structure on in vitro and in vivo activity, four general features of the molecules were varied: the 2-substituent, the 1-hydroxyl group, substitution on the naphthalene rings, and the 1,2-disubstituted naphthalene unit itself. 2-Benzyl-1-naphthol (5a, DuP 654) shows a very attractive profile of topical antiinflammatory activity and is currently in clinical trials as a topically applied antipsoriatic agent.

The possible utility of DuP 654, a potent 5-lipoxygenase inhibitor, for treating human inflammatory skin disease was investigated in murine skin treated with 1.0 mg arachidonic acid (AA). When DuP 654 was applied to murine skin treated with AA, it inhibited the resulting inflammation and influx of cells. High performance liquid chromatography and radioimmunoassay analysis of lipid extracts from AA-treated ears indicated that the influx of polymorphonuclear leukocytes (PMN) was temporally preceded by an appearance of significant amounts of 5-HETE (6.7 +/- 1.4 ng/ear) and Leukotriene B4 LTB4 0.92 +/- 0.2 ng/ear) when compared with extracts of untreated ears (5-HETE, 02 +/- 0.3 ng/ear; LTB4, less than 0.1 ng/ear). The levels of the 5-lipoxygenase products were reduced by treatment with 10 micrograms/ear DUP 654. Lipid extracts from AA-treated ears contain chemotactic activity for human PMN and this chemotactic activity in the AA-treated ears could be reduced but not eliminated by immunosorption with anti-LTB4 antibodies coupled to protein A-agarose. The appearance of the chemotactic activity was inhibited by DuP 654. Taken together, these data suggest that DuP 654 may have utility in human inflammatory skin disease.

Recent work suggests that one of the common biochemical characteristics of skin inflammatory diseases such as psoriasis is altered arachidonic acid metabolism with elevated levels of prostaglandins and leukotrienes. DuP 654, a 2-substituted 1-naphthol, is an exceptionally potent inhibitor of 5-lipoxygenase. DuP 654 was tested in various models of skin inflammation and was found to be potent at inhibiting edema induced by the topical application of arachidonic acid, tetradecanoyl phorbol acetate or the calcium ionophore A23187. DuP 654 was also effective in a murine model of contact sensitivity. DuP 654 was effective at reducing the numbers of infiltrating polymorphonuclear leukocytes in AA and TPA induced edema. These data, taken together, suggest that DuP 654 may be effective in treating human skin diseases.