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Human epithelial 15-lipoxygenase-2 (h15-LOX-2, ALOX15B) is expressed in many tissues and has been implicated in atherosclerosis, cystic fibrosis and ferroptosis. However, there are few reported potent/selective inhibitors that are active ex vivo. In the current work, we report newly discovered molecules that are more potent and structurally distinct from our previous inhibitors, MLS000545091 and MLS000536924 (Jameson et al, PLoS One, 2014, 9, e104094), in that they contain a central imidazole ring, which is substituted at the 1-position with a phenyl moiety and with a benzylthio moiety at the 2-position. The initial three molecules were mixed-type, non-reductive inhibitors, with IC 50 values of 0.34 ± 0.05 μM for MLS000327069, 0.53 ± 0.04 μM for MLS000327186 and 0.87 ± 0.06 μM for MLS000327206 and greater than 50-fold selectivity versus h5-LOX, h12-LOX, h15-LOX-1, COX-1 and COX-2. A small set of focused analogs was synthesized to demonstrate the validity of the hits. In addition, a binding model was developed for the three imidazole inhibitors based on computational docking and a co-structure of h15-LOX-2 with MLS000536924. Hydrogen/deuterium exchange (HDX) results indicate a similar binding mode between MLS000536924 and MLS000327069, however, the latter restricts protein motion of helix-α2 more, consistent with its greater potency. Given these results, we designed, docked, and synthesized novel inhibitors of the imidazole scaffold and confirmed our binding mode hypothesis. Importantly, four of the five inhibitors mentioned above are active in an h15-LOX-2/HEK293 cell assay and thus they could be important tool compounds in gaining a better understanding of h15-LOX-2's role in human biology. As such, a suite of similar pharmacophores that target h15-LOX-2 both in vitro and ex vivo are presented in the hope of developing them as therapeutic agents., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Human platelet 12-(S)-Lipoxygenase (12-LOX) is a fatty acid metabolizing oxygenase that plays an important role in platelet activation and cardiometabolic disease. ML355 is a specific 12-LOX inhibitor that has been shown to decrease thrombosis without prolonging hemostasis and protect human pancreatic islets from inflammatory injury. It has an amenable drug-like scaffold with nM potency and encouraging ADME and PK profiles, but its binding mode to the active site of 12-LOX remains unclear. In the current work, we combined computational modeling and experimental mutagenesis to propose a model in which ML355 conforms to the "U" shape of the 12-LOX active site, with the phenyl linker region wrapping around L407. The benzothiazole of ML355 extends into the bottom of the active site cavity, pointing towards residues A417 and V418. However, reducing the active site depth alone did not affect ML355 potency. In order to lower the potency of ML355, the cavity needed to be reduced in both length and width. In addition, H596 appears to position ML355 in the active site through an interaction with the 2-methoxy phenol moiety of ML355. Combined, this binding model suggested that the benzothiazole of ML355 could be enlarged. Therefore, a naphthyl-benzothiazole derivative of ML355, Lox12Slug001, was synthesized and shown to have 7.2-fold greater potency than ML355. This greater potency is proposed to be due to additional van der Waals interactions and pi-pi stacking with F414 and F352. Lox12Slug001 was also shown to be highly selective against 12-LOX relative to the other LOX isozymes and more importantly, it showed activity in rescuing human islets exposed to inflammatory cytokines with comparable potency to ML355. Further studies are currently being pursued to derivatize ML355 in order to optimize the additional space in the active site, while maintaining acceptable drug-like properties., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The most common inflammatory disease of the airways is asthma among children affecting around 235 million people worldwide. 5-Lipoxygenase (5-LOX) is a crucial enzyme which helps in the conversion of arachidonic acid (AA) to leukotrienes (LTs), the lipid mediators. It is associated with several inflammation related disorders such as asthma, allergy, and atherosclerosis. Therefore, it is considered as a promising target against inflammation and asthma. Currently, the only drug against 5-LOX which is available is Zileuton, while a few inhibitors are in clinical trial stages such as Atreleuton and Setileuton. So, there is a dire requirement in the area of progress of novel 5-LOX inhibitors which necessitates an understanding of their structure activity relationship and mode of action. In this review, novel 5-LOX inhibitors reported so far, their structural design, SAR and developmental strategies along with clinical updates are discussed over the last two decades., (Copyright © 2019. Published by Elsevier Ltd.)

5-Lipoxygenase (5-LOX) is a key enzyme involved in the biosynthesis of pro-inflammatory leukotrienes, leading to asthma. Developing potent 5-LOX inhibitors especially, natural product based ones, are highly attractive. Coumaperine, a natural product found in white pepper and its derivatives were herein developed as 5-LOX inhibitors. We have synthesized twenty four derivatives, characterized and evaluated their 5-LOX inhibition potential. Coumaperine derivatives substituted with multiple hydroxy and multiple methoxy groups exhibited best 5-LOX inhibition. CP-209, a catechol type dihydroxyl derivative and CP-262-F2, a vicinal trihydroxyl derivative exhibited, 82.7% and 82.5% inhibition of 5-LOX respectively at 20 µM. Their IC 50 values are 2.1 ± 0.2 µM and 2.3 ± 0.2 µM respectively, and are comparable to zileuton, IC 50  = 1.4 ± 0.2 µM. CP-155, a methylenedioxy derivative (a natural product) and CP-194, a 2,4,6-trimethoxy derivative showed 76.0% and 77.1% inhibition of 5-LOX respectively at 20 µM. Antioxidant study revealed that CP-209 and 262-F2 (at 20 µM) scavenged DPPH radical by 76.8% and 71.3% respectively. On the other hand, CP-155 and 194 showed very poor DPPH radical scavenging activity. Pseudo peroxidase assay confirmed that the mode of action of CP-209 and 262-F2 were by redox process, similar to zileuton, affecting the oxidation state of the metal ion in the enzyme. On the contrary, CP-155 and 194 probably act through some other mechanism which does not involve the disruption of the oxidation state of the metal in the enzyme. Molecular docking of CP-155 and 194 to the active site of 5-LOX and binding energy calculation suggested that they are non-competitive inhibitors. The In-Silico ADME/TOX analysis shows the active compounds (CP-155, 194, 209 and 262-F2) are with good drug likeliness and reduced toxicity compared to existing drug. These studies indicate that there is a great potential for coumaperine derivatives to be developed as anti-inflammatory drug., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Some novel indolizine derivatives were synthesized by bioisosteric modification of imidazo[1,2-a]pyridine for anti-inflammatory activity. The physicochemical characterization and structure of compounds were elucidated by state of the art spectroscopic technique. Induced fit docking was performed for initial screening to elucidate the interactions with corresponding amino acids of cyclooxygenase (COX-1, COX-2) and lipoxygenase (LOX) enzymes. The target compounds 53-60 were then evaluated against in vivo carrageenan and arachidonic acid induced rat paw edema models for anti-inflammatory activity. Amongst all the synthesized derivatives, compound 56 showed the significant anti-inflammatory activity in both rat paw edema models with very less ulcerogenic liability in comparison to standard diclofenac, celecoxib, and zileuton. The compounds 56 was further assessed to observe in vitro enzyme inhibition assay on both cyclooxygenase and lipoxygenase enzyme where it showed a preferential and selective non-competitive enzyme inhibition towards the COX-2 (IC 50 =14.91μM, Ki=0.72µM) over COX-1 (IC 50 >50μM) and a significant non-competitive inhibition of soybean lipoxygenase enzyme (IC 50 =13.09μM, Ki=0.92µM). Thus, in silico, in vivo, and in vitro findings suggested that the synthesized indolizine compound 56 has a dual COX-2 and LOX inhibition characteristic and parallel in vivo anti-inflammatory activity in comparison to the standard drugs., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A new series of 11-keto-β-boswellic acid and 3-O-acetyl-11-keto-β-boswellic acid analogs (5, 7, 8, 10, 13, 18a-d, 27a-c, 28a-d) were synthesized by modification of hydroxyl and acid functional moieties of boswellic acids. The structures of these analogs were confirmed by spectral data analysis ( 1 H, 13 C NMR and mass). Compounds 18b, 27a and 8 showed potent 5-lipoxygenase enzyme inhibitory activity (IC 50 : 19.53, 20.31 and 44.14μg/mL). The computational studies revealed that selectivity of AKBA is due to its fitment into the 5-LOX receptor, which is missing for the other enzymes like 12-LOX, COX-1 and COX-2. Our study found potentiating effects of 2-formyl and 3-keto substituents in reviving inactive AKBA analogues possessing essential COOH group at 4th position., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A versatile synthesis of novel 5-hydroxylaminoisoxazoles bearing adamantane moieties has been accomplished using the heterocyclization reactions of readily available unsaturated esters by the treatment with tetranitromethane in the presence of triethylamine and subsequent reduction of resulting 5-nitroisoxazoles by SnCl2 with the participation of THF. A number of obtained isoxazole derivatives were evaluated for their antioxidative activity, inhibition of lipoxygenases and impact on the rat liver mitochondria. The majority of tested compounds demonstrated moderate antiradical activity in DPPH test (up to EC50 16μM). The same compounds strongly inhibited soybean lipoxygenase (up to IC50 0.4μM) and Fe(2+)- and Fe(3+)-induced lipid peroxidation (LP) of rat brain cortex homogenate (up to IC50 0.3μM). All tested isoxazole derivatives promoted the phosphorylating respiratory activity simultaneously with maximal stimulated respiratory activity of mitochondria and do not reveal any toxicity towards the primary culture of rat cortex neurons., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Selective alkylation of the antipsoriatic drug dithranol (DTR) at C-10 with tert-butyl bromoacetate, followed by acid-mediated deprotection, produced the corresponding carboxylic acid 4 which was coupled with selectively protected polyamines (PAs), such as putrescine (PUT), spermidine (SPD) and spermine (SPM), dopamine and aliphatic amines and substituted benzylamines producing a series of DTR-PA hybrids, after acid-mediated deprotection, as well as simple amides. The compounds were tested as antioxidants and inhibitors of lipoxygenase (LOX). The amides 4,4'-dimethoxybenzhydrylamide 13 (86% and 95%), 2,4-dimethoxybenzylamide 12 (87% and 81%) and dodecylamide 9 (98% and 74%), and the hybrid DTR-SPM (7) (93% and 87%), showed the highest antioxidant activity in the DPPH and AAPH assays, whereas the most potent inhibitors of LOX were amide 13 (IC50=7 μM), the benzylamide 10 (IC50=7.9 μM) and the butylamide 8 (IC50=10 μM). Molecular binding studies showed that binding of these derivatives into the hydrophobic domain blocks approach of substrate to the active site, inhibiting soybean LOX. Amide 13 presented the highest anti-inflammatory activity (79.7%). The DTR moiety was absolutely necessary for securing high anti-inflammatory potency. Ethyl ester 3 (IC50=0.357 μM) and the amides 9 (IC50=0.022 μM) and 13 (IC50=0.56 μM) exhibited higher antiproliferative activity than DTR (IC50=0.945 μM) on HaCaT keratinocytes whereas amide 13 generally presented better cytocompatibility. Amide 13 is a very promising lead compound for further development as an anti-inflammatory and antiproliferative agent., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In the present project, a series of coumarin analogues, were synthesised and evaluated for their antioxidant and soybean lipoxygenase inhibitory activity. A variety of structural modifications on the coumarin scaffold revealed interesting structure–activity relationships concerning the different biological assays. Prenyloxy-coumarins 9 and 10 displayed the best combined inhibition of lipid peroxidation and soybean lipoxygenase. Thiocoumarins 11 and 14 were identified as potent lipoxygenase inhibitors whereas hydrazone analogues 15 and 16 were efficient DPPH radical scavengers.

Arachidonic acid and its metabolites have generated high level of interest among researchers due to their vital role in inflammation. The inhibition of enzymes involved in arachidonic acid metabolism has been considered as synergistic anti-inflammatory effect. A series of novel α,β-unsaturated carbonyl based compounds were synthesized and evaluated for their inhibitory activity on secretory phospholipase A₂ (sPLA₂), cyclooxygenases (COX), soybean lipoxygenase (LOX) in addition to proinflammatory cytokines comprising IL-6 and TNF-α. Six α,β-unsaturated carbonyl based compounds (2, 3, 4, 12, 13 and 14) exhibited strong inhibition of sPLA₂ activity, with IC₅₀ values in the range of 2.19-8.76 μM. Nine compounds 1-4 and 10-14 displayed inhibition of COX-1 with IC₅₀ values ranging from 0.37 to 1.77 μM (lower than that of reference compound), whereas compounds 2, 10, 13 and 14 strongly inhibited the COX-2. The compounds 10-14 exhibited strong inhibitory activity against LOX enzyme. All compounds were evaluated for the inhibitory activities against LPS-induced TNF-α and IL-6 release in the macrophages. On the basis of screening results, five active compounds 3, 4, 12, 13 and 14 were found strong inhibitors of TNF-α and IL-6 release in a dose-dependent manner. Molecular docking experiments were performed to clarify the molecular aspects of the observed COX and LOX inhibitory activities of the investigated compounds. Present findings increases the possibility that these α,β-unsaturated carbonyl based compounds might serve as beneficial starting point for the design and development of improved anti-inflammatory agents., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Human 5-lipoxygenase (5-LOX) is a well-validated target for anti-inflammatory therapy. Development of novel 5-LOX inhibitors with higher activities is highly demanded. In previous study, we have built a model for the active conformation of human 5-LOX, and identified naphthalen-1-yl 3,5-dinitrobenzoate (JMC-4) as a 5-LOX inhibitor by virtual screening. In the present work, 3,5-dinitrobenzoate-based 5-lipoxygenase inhibitors were developed. Twenty aryl 3,5-dinitrobenzoates, N-aryl 3,5-dinitrobenzamides and analogues were designed and synthesized. Several of them were found with significantly increased activities according to cell-free assay and human whole blood assay. The structure-activity relationship study may provide useful insights for designing effective 5-LOX inhibitors., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A catalytic asymmetric synthesis of (S)-(-)-zearalenone is reported using asymmetric allylic alkylation for the introduction of the stereocenter. (S)-(-)-Zearalenone turned out to be a novel lipoxygenase inhibitor., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) enzyme have been found to play a role in promoting growth in colon cancer cell lines. The di-tert-butyl phenol class of compounds has been found to inhibit both COX-2 and 5-LOX enzymes with proven effectiveness in arresting tumor growth. In the present study, the structural analogs of 2,6 di-tert-butyl-p-benzoquinone (BQ) appended with hydrazide side chain were found to inhibit COX-2 and 5-LOX enzymes at micromolar concentrations. Molecular docking of the compounds into COX-2 and 5-LOX protein cavities indicated strong binding interactions supporting the observed cytototoxicities. The signaling interaction between endogenous hyaluronan and CD44 has been shown to regulate COX-2 activities through ErbB2 receptor tyrosine kinase (RTK) activation. In the present studies it has been observed for the first time, that three of our COX/5-LOX dual inhibitors inhibit proliferation upon hydrazide substitution and prevent the activity of pro-angiogenic factors in HCA-7, HT-29, Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressed in colon cancer cells, through inhibition of the hyaluronan/CD44v6 cell survival pathway. Since there is a substantial enhancement in the antiproliferative activities of these compounds upon hydrazide substitution, the present work opens up new opportunities for evolving novel active compounds of BQ series for inhibiting colon cancer., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A series of 4,5-diaryl-1H-imidazole-2(3H)-thione was synthesized and their inhibitory potency against soybean 15-lipoxygenase and free radical scavenging activities were determined. Compound 11 showed the best IC(50) for 15-LOX inhibition (IC(50) = 4.7 μM) and free radical scavenging activity (IC(50) = 14 μM). Methylation of SH at C(2) position of imidazole has dramatically decreased the 15-LOX inhibition and radical scavenging activity as it can be observed in the inactive compound 14 (IC(50) >250 μM). Structure activity similarity (SAS) showed that the most important chemical modification in this series was methylation of SH group and Docking studies revealed a proper orientation for SH group towards Fe core of the 15-LOX active site. Therefore it was concluded that iron chelating could be a possible mechanism for enzyme inhibition in this series of compounds., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

15-Lipoxygenases are one of the nonheme iron-containing proteins with ability of unsaturated lipid peroxidation in animals and plants. The critical role of the enzymes in formation of inflammations, sensitivities and some of cancers has been demonstrated in mammalians. Importance of the 15-lipoxygenases leads to development of mechanistic studies, products analysis and synthesis of their inhibitors. In this work new series of the 3-allyl-4-allyoxyaniline amides and 3-allyl-4-prenyloxyaniline amides were designed, synthesized and their inhibitory potency against soybean 15-lipoxygenase were determined. Among the synthetic amides, 3-allyl-4-(farnesyloxy)-adamantanilide showed the most potent inhibitory activity by IC(50) value of 0.69 μM. SAR studies showed that in spite of prenyl length increases, the effects of the amide size and its electronic properties on the inhibitory potency became predominant. The SAR studies was also showed that the orientation of allyl and prenyloxy moieties toward Fe core of the SLO active site pocket is the most suitable location for enzyme inhibition., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Lipoxygenases catalyze the oxidation of unsaturated fatty acids, such as linoleic acid, which play a crucial role in inflammatory responses. Selective inhibitors may provide a new therapeutic approach for inflammatory diseases. In this study, we describe the identification of a novel soybean lipoxygenase-1 (SLO-1) inhibitor and a potato 5-lipoxygenase (5-LOX) activator from a screening of a focused compound collection around the natural product anacardic acid. The natural product anacardic acid inhibits SLO-1 with an IC(50) of 52 μM, whereas the inhibitory potency of the novel mixed type inhibitor 23 is fivefold enhanced. In addition, another derivative (21) caused non-essential activation of potato 5-LOX. This suggests the presence of an allosteric binding site that regulates the lipoxygenase activity., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A class of 5-lipoxygenase (5-LO) inhibitors characterized by a central 5-benzylidene-2-phenyl-thiazolinone scaffold was synthesized as a new series of molecular modifications and extensions of a previously reported series. Compounds were tested in a cell-based and a cell-free assay and furthermore evaluated for their influence on cell viability. The presented substituted thiazolinone scaffold turned out to be essential for both the 5-LO inhibitory activity and the non-cytotoxic profile. With (Z)-5-(4-methoxybenzylidene)-2-(naphthalen-2-yl)-5H-thiazol-4-one (2k, ST1237), a potent, direct, non-cytotoxic 5-LO inhibitor with IC(50) of 0.08 μM and 0.12 μM (cell-free assay and intact cells), we present a promising lead optimization and development for further investigations as novel anti-inflammatory drug., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The present study describes a convenient method for the synthesis of new lipoxygenase inhibitors, 4-(toluene-4-sulfonylamino)-benzoic acids from p-amino benzoic acid. Reaction of p-amino benzoic acid with p-toluenesulfonyl chloride provided thirteen N- and O-alkylation products 4a-4m in moderate to good yields. Lipoxygenase inhibition of newly formed sulfonamide derivatives was investigated and some of these compounds 4m, 4g, 4e, 4f and 4j showed good lipoxygenase inhibitory activities with IC(50) values ranged between 15.8 ± 0.57 and 91.7 ± 0.61 μmol whilst all other compounds exhibited mild anti-lipoxygenase activities with IC(50) values ranged between 139.2 ± 0.75 and 232.1 ± 0.78 μmol. N-alkylated products were more active against the enzyme than O-alkylated or both N- and O-alkylated ones. All synthesized sulfonamides were recrystallized in chloroform to give these title compounds which were characterized using FTIR, (1)H NMR, (13)C NMR, elemental analysis and single crystal X-ray diffraction techniques., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

We report the design, the synthesis and the biological evaluation of the analgesic and anti-inflammatory activities of furoxanyl N-acylhydrazones (furoxanyl-NAH) by applying molecular hybridization approach. Hybrid compounds with IL-8-release inhibition capabilities were identified. Among them, furoxanyl-NAH, 17, and benzofuroxanyl-derivative, 24, together with furoxanyl-NAH derivative, 31, without IL-8 inhibition displayed both orally analgesic and anti-inflammatory activities. These hybrid derivatives do not have additional LOX- or COX-inhibition activities. For instance, LOX-inhibition by furoxanyl-NAH derivative, 42, emerged as a structural lead to develop new inhibitors. The lack of mutagenicity of the active derivatives 17, 31, and 42, allow us to propose them as candidates for further clinical studies. These results confirmed the success in the exploitation of hybridization strategy for identification of novel N-acylhydrazones (NAH) with optimized activities., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

3-(4-Bromophenyl)-6-nitrobenzo[1.3.2]dithiazolium ylide 1,1-dioxide (5) was discovered as a new prototype for dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX). Thus, the structure-activity relationships of benzo[1.3.2]dithiazolium ylide 1,1-dioxide skeleton were carried out. The 6-NO(2) group played an essential role in the inhibitory activity. In addition, moderate-sized lipophilic substituents at the para-position of the 3-aryl moiety were required for dual COX-2/5-LOX inhibitory activity. Among the identified potent dual inhibitors, 3-(4-tbutylphenyl) derivative 30c (IC(50) values of 0.27 μM and 0.30 μM against COX-2 and 5-LOX, respectively) and 3-(4-biphenyl) derivative 30f (IC(50) values of 0.50 μM and 0.15μM against COX-2 and 5-LOX, respectively) were the most potent dual COX-2/5-LOX inhibitors. Intraperitoneal administration of 30c at 100mg/kg demonstrated potent acute anti-inflammatory activity. As a result, benzo[1.3.2]dithiazolium ylide 1,1-dioxide represented a novel scaffold for the exploitation in developing dual COX-2/5-LOX inhibitors., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

5-Lipoxygenase (5-LO) and microsomal prostaglandin E₂ synthase (mPGES)-1 are key enzymes in the biosynthesis of leukotrienes and prostaglandin (PG)E₂, respectively, and are considered as valuable targets for the treatment of inflammatory diseases. Here, we present the identification of 2-mercaptohexanoic acid derivatives as dual inhibitors of 5-LO and mPGES-1. The lead compound 2(4-(3-biphenyloxypropoxy)phenylthio)hexanoic acid (21) inhibits human 5-LO and mPGES-1 in cell-free assays with an IC₅₀ = 3.5 and 2.2 μM, respectively, and suppresses 5-LO in intact cells with even a higher potency (IC₅₀=0.9 μM). Compound 21 (10 μM) neither significantly inhibited the related 12- or 15-LOs nor cyclooxygenase-1 and -2 or cytosolic phospholipase A₂. Based on the selective and potent inhibition of 5-LO and mPGES-1, further assessment of these 2-mercaptohexanoic acids in preclinical models of inflammation are warranted., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Cyclooxygenase-1/2 (COX-1/2) and 5-lipoxygenase (5-LOX) are enzymes in two different pathways in the inflammatory process. In the present study, a variety of new nimesulide derivatives were synthesized through incorporation of a 5-LOX pharmacophore into nimesulide followed with some structural modifications, which were then characterized for dual enzyme inhibitors for these two types of enzymes. Their structure-activity relationships (SARs) were studied, and compound 20f was found to be an excellent dual enzyme inhibitor. Its binding conformation and interaction mode were studied with molecular docking experiments. Compound 20f could become a lead compound for further development for potential anti-inflammatory drugs., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

With the increasing realization that modulating a multiplicity of targets can be an asset in the treatment of multifactorial disorders, we hereby report the synthesis and evaluation of the first compounds in which antioxidant, anti-inflammatory as well as squalene synthase (SQS) inhibitory activities are combined by design, in a series of simple molecules, extending their potential range of activities against the multifactorial disease of atherosclerosis. The activity of the initially synthesized antihyperlipidemic morpholine derivatives (1-6), in which we combined several pharmacophore moieties, was evaluated in vitro (antioxidant, inhibition of SQS and lipoxygenase) and in vivo (anti-dyslipidemic and anti-inflammatory effect). We further compared the in vitro SQS inhibitory action of these derivatives with theoretically derived molecular interactions by performing an in silico docking study using the X-ray crystal structure of human SQS. Based on low energy preferred binding modes, we designed potentially more potent SQS ligands. We proceeded with synthesizing and evaluating these new structures (7-12) in vitro and in vivo, to show that the new derivatives were significantly more active than formerly developed congeners, both as SQS inhibitors (20-70-fold increase in activity) and antioxidants (4-30-fold increase in activity). A significant correlation between experimental activity [Log(1/IC(50))] and the corresponding binding free energy (ΔG(b)) of the docked compounds was shown. These results, taken together, show a promising alternative and novel approach for the design and development of multifunctional antiatherosclerosis agents., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

5-Lipoxygenase (5-LOX) is important enzyme in the biosynthesis of leukotrienes, and is a potential target in the treatment of asthma and allergy. We designed and synthesized a series of benzoxazoles and benzothiazoles as 5-LOX inhibitors. Fourteen compounds prepared showed the inhibition of LTC4 formation with IC(50) value of 0.12-23.88 μM. Also two compounds 2d and 2g showed improved airway hypersensitiveness., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Ten novel mono- and di-O-prenylated chalcone derivatives were designed on the basis of a homology derived molecular model of 5-lipoxygenase (5-LOX). The compounds were docked into 5-LOX active site and the binding characteristics were quantified using LUDI. To verify our theoretical assumption, the molecules were synthesized and tested for their 5-LOX inhibitory activities. The synthesis was carried out by Claisen-Schmidt condensation reaction of mono- and di-O-prenylated acetophenones with appropriate aldehydes. 5-LOX in vitro inhibition assay showed higher potency of di-O-prenylated chalcones than their mono-O-prenylated chalcone analogs. Compound 5e exhibited good inhibition with an IC(50) at 4 microM. The overall trend for the binding energies calculated and LUDI score was in good qualitative agreement with the experimental data. Further, the compound 5e showed potent anti-proliferative effects (GI(50) at 9 microM) on breast cancer cell line, MCF-7., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Four derivatives of schisandrin, a major dibenzo[a,c]cyclooctadiene lignan of Schisandra chinensis (Turcz.) Baillon were synthesized and structurally characterized by means of NMR and mass spectroscopy. Furthermore, axial chirality of the biphenyl system was determined by comparison of calculated with measured circular dichroism (CD) spectra. Three of the obtained derivatives showed a ring contraction during chemical modification. While the original lignans were inactive on the performed bioassays, the compounds which showed the cycloheptadiene skeleton revealed remarkable activities. For the inhibition of LTB(4) production the IC(50) values of aR-6,7-dihydro-6-(1'-hydroxyethyl)-3,9-dimethoxy-6-methyl-5H-dibenzo[a,c]cycloheptene-1,2,10,11-tetraol (6) and aR-6-(1'-iodoethyl)-1,2,3,9,10,11-hexamethoxy-6-methyl-5H-dibenzo[a,c]cycloheptene (8) were 4.2+/-0.3microM and 4.5+/-0.2microM, respectively. aR-6,7-Dihydro-6-(1'-hydroxyethyl)-6-methyl-5H-dibenzo[a,c]cycloheptene-1,2,3,9,10,11-hexaol (5) revealed dual inhibition on COX-2 (IC(50) 32.1+/-2.5microM) and on LTB(4) production (37.3+/-5.5% inhibition at 50microM)., (Copyright 2010. Published by Elsevier Ltd.)

In the present study we have discovered compound 1, a benzo[1.3.2]dithiazolium ylide-based compound, as a new prototype dual inhibitor of cyclooxygenase (COX) and 5-lipoxygenase (5-LOX). Compound 1 was initially discovered as a COX-2 inhibitor, resulting indirectly from the COX-2 structure-based virtual screening that identified compound 2 as a virtual hit. Compounds 1 and 2 inhibited COX-1 and COX-2 in mouse macrophages with IC(50) in the range of 1.5-18.1microM. Both compounds 1 and 2 were also found to be potent inhibitors of human 5-LOX (IC(50)=1.22 and 0.47microM, respectively). Interestingly, compound 1 also had an inhibitory effect on tumor necrosis factor-alpha (TNF-alpha) production (IC(50)=0.44microM), which was not observed with compound 2. Docking studies suggested the (S)-enantiomer of 1 as the biologically active isomer that binds to COX-2. Being a cytokine-suppressive dual COX/5-LOX inhibitor, compound 1 may represent a useful lead structure for the development of advantageous new anti-inflammatory agents., (Copyright 2009 Elsevier Ltd. All rights reserved.)

A series of 2'-hydroxy-chalcones and their oxidative cyclization products, aurones, have been synthesized and tested for their antioxidant and lipoxygenase inhibitory activity. The natural product aureusidin (31) was synthesized in high yield by a new approach. An extensive structure-relationship study was performed and revealed that several chalcones and aurones possess an appealing pharmacological profile combining high antioxidant and lipid peroxidation activity with potent soybean LOX inhibition.

A group of 4-allyloxyaniline amides 5a-o were designed, synthesized and evaluated as potential inhibitors of soybean 15-lipoxygenase (SLO) on the basis of eugenol and esteragol structures. Compound 5e showed the best IC(50) in SLO inhibition (IC(50)=0.67+/-0.06 microM). All compounds were docked in SLO active site retrieved from RCSB Protein Data Bank (PDB entry: 1IK3) and showed that allyloxy group of compounds is oriented towards the Fe(3+)-OH moiety in the active site of enzyme and fixed by hydrogen bonding with two conserved His(513) and Gln(716). It is resulted that molecular volume of the amide moiety would be a major factor in inhibitory potency variation of the synthetic amides, where the hydrogen bonding of the amide group could also involve in the activity of the inhibitors.

A series of 20 novel 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines were designed, synthesized, and screened in vitro for anti-inflammatory activity. These compounds were designed for evaluation as dual inhibitors of cyclooxygenases (COX-1 and COX-2) and lipoxygenases (LOX-5, LOX-12, and LOX-15) that are responsible for inflammation and pain. All pyrazoline molecules prepared are optically active and compounds that are more potent in COX-2 inhibitory activity (5a and 5f) were resolved by chiral column and each enantiomer was tested for cyclooxygenase inhibitory activity. Molecular modeling and comparison of molecular models of 5a enantiomers with that of celecoxib model shows that 5a (enantiomer-1) and 5a (enantiomer-2) have more hydrogen bonding interactions in the catalytic domain of COX-2 enzyme than celecoxib. Compounds 5a, 5e, and 5f showed moderate to good LOX-5 and LOX-15 inhibitory activity and this is comparable to that of celecoxib and more potent than rofecoxib.

A group of 4-allyl-2-methoxyphenol (eugenol) esters were designed, synthesized, and evaluated as potential inhibitors of soybean 15-lipoxygenase (SLO). Compounds 4c, 4d 4f, 4p, and 4q showed the best IC(50) in SLO inhibition (IC(50)=1.7, 2.3, 2.1, 2.2, and 0.017microM, respectively). All compounds were docked into SLO active site and showed that allyl group of compounds is oriented toward the iron atom in the active site of SLO. It is assumed that lipophilic interaction of ligand-enzyme would be in charge of inhibiting the enzyme activity. The selectivity of eugenol derivatives in inhibiting 15-HLOb was also compared with 15-HLOa by molecular modeling and multiple alignment techniques.

Human lipoxygenase (hLO) isozymes have been implicated in a number of disease states and have attracted much attention with respect to their inhibition. One class of inhibitors, the flavonoids, have been shown to be potent lipoxygenase inhibitors but their study has been restricted to those compounds found in nature, which have limited structural variability. We have therefore carried out a comprehensive study to determine the structural requirements for flavonoid potency and selectivity against platelet 12-hLO, reticulocyte 15-hLO-1, and prostate epithelial 15-hLO-2. We conclude from this study that catechols are essential for high potency, that isoflavones and isoflavonones tend to select against 12-hLO, that isoflavons tend to select against 15-hLO-1, but few flavonoids target 15-hLO-2.

Human lipoxygenases (hLO) have been implicated in a variety of diseases and cancers and each hLO isozyme appears to have distinct roles in cellular biology. This fact emphasizes the need for discovering selective hLO inhibitors for both understanding the role of specific lipoxygenases in the cell and developing pharmaceutical therapeutics. To this end, we have modified a known lipoxygenase assay for high-throughput (HTP) screening of both the National Cancer Institute (NCI) and the UC Santa Cruz marine extract library (UCSC-MEL) in search of platelet-type 12-hLO (12-hLO) selective inhibitors. The HTP screen led to the characterization of five novel 12-hLO inhibitors from the NCI repository. One is the potent but non-selective michellamine B, a natural product, anti-viral agent. The other four compounds were selective inhibitors against 12-hLO, with three being synthetic compounds and one being alpha-mangostin, a natural product, caspase-3 pathway inhibitor. In addition, a selective inhibitor was isolated from the UCSC-MEL (neodysidenin), which has a unique chemical scaffold for a hLO inhibitor. Due to the unique structure of neodysidenin, steady-state inhibition kinetics were performed and its mode of inhibition against 12-hLO was determined to be competitive (K(i)=17microM) and selective over reticulocyte 15-hLO-1 (K(i) 15-hLO-1/12-hLO>30).

Lipoxygenase catalyzes the first two steps of the transformation of arachidonic acid into leukotrienes which are implicated in host defense reactions. It is well known that many acids possess potent anti-inflammatory activity. Taking into account that compounds bearing a thienyl, naphthyl, pyrollyl, and 2,4-di-tert-butyl-phenol moieties possess anti-inflammatory activity which is related to their capacity to transfer electrons and to scavenge reactive oxygen species, we synthesized some new aryl-acetic acids and we explored their ability to inhibit soybean lipoxygenase, to present antioxidant and anti-inflammatory activities, and to interact with glutathione. The compounds have shown important antioxidant activity, medium anti-inflammatory activity, and very good inhibition of soybean lipoxygenase. Compound 3-(3,5-di-tert-butyl-2-hydroxy-phenyl)-2-phenyl-acrylic acid (1i) showed significant in vitro LO inhibition (IC(50) 65 microM). The results are discussed in terms of structural and physicochemical characteristics of the compounds. The structures of the synthesized compounds were confirmed by spectral and elemental analysis. Their lipophilicity are experimentally determined by RPTLC method.

A group of 2-substituted pyrimido[4,5-b][1,4]benzothiazines were designed, synthesized, and evaluated as potential inhibitors of 15-lipoxygenase (15-LO). Compounds 4d and 4e showed the best IC50 of 15-LO inhibition (IC50=18 and 34 microM, respectively). All compounds were docked into 15-LO. As a result the sulfur atom was oriented toward the iron atom of the active site of 15-LO. We suggest the interaction of the iron atom is essential for the activity of the inhibitors.

Six novel ibuprofen derivatives and related structures, incorporating a proline moiety and designed for neurodegenerative disorders, are studied. They possess anti-inflammatory properties and three of them inhibited lipoxygenase. One compound was found to inhibit cyclooxygenase (COX)-2 production in spleenocytes from arthritic rats. The HS-containing compounds are potent antioxidants and one of them protected against glutathione loss after cerebral ischemia/reperfusion. They demonstrated lipid-lowering ability and seem to acquire low gastrointestinal toxicity. Acetylcholinesterase inhibitory activity, found in two of these compounds, may be an asset to their actions.

A group of 4-(4-methanesulfonylphenyl)-3-phenyl-2(5H)furanones possessing an acetyl, 3-oxobut-1-ynyl, [hydroxyl(or alkoxy)imino]alkyl, [hydroxyl(or alkoxy)imino]alkynyl, and N-alkoxy(or N-phenoxy)carbonyl-N-hydroxy-N-ethylamino substituents at the para-position of the C-3 phenyl ring of rofecoxib were synthesized. This group of compounds was designed for evaluation as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs) that exhibit in vivo anti-inflammatory and analgesic activities. In vitro COX-1/COX-2, and 5-LOX/15-LOX, isozyme inhibition structure-activity relationships identified 3-[4-(1-hydroxyimino)ethylphenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (17a) having an optimal combination of COX-2 (COX-2 IC50 = 1.4 microM; COX-2 SI > 71), and 5-LOX and 15 LOX (5-LOX IC50 = 0.28 microM; 15-LOX IC50 = 0.32 microM), inhibitory effects. It was also discovered that 3-[4-(3-hydroxyiminobut-1-ynyl)phenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (18a) possesses dual COX-2 (IC50 = 2.7 microM) and 5-LOX (IC50 = 0.30 microM) inhibitor actions. Further in vivo studies employing a rat carrageenan-induced paw edema model showed that the oxime compounds (17a, 18a) were more potent anti-inflammatory agents than the 5-LOX inhibitor caffeic acid, and 15-LOX inhibitor nordihydroguaiaretic acid (NDGA), but less potent than the selective COX-2 inhibitor celecoxib. The results of this investigation showed that incorporation of a para-oxime moiety on the C-3 phenyl ring of rofecoxib provides a suitable template for the design of dual inhibitors of the COX and LOX enzymes.

A group of (E)-3-(4-methanesulfonylphenyl)acrylic acids possessing a substituted-phenyl ring (4-H, 4-Br, 3-Br, 4-F, 4-OH, 4-OMe, 4-OAc, and 4-NHAc) attached to the acrylic acid C-2 position were prepared using a stereospecific Perkin condensation reaction. A related group of compounds having 4- and 3-(4-isopropyloxyphenyl)phenyl, 4- and 3-(2,4-difluorophenyl)phenyl and 4- and 3-(4-methanesulfonylphenyl)phenyl substituents attached to the acrylic acid C-2 position were also synthesized, using a palladium-catalyzed Suzuki cross-coupling reaction, for evaluation as dual cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) inhibitors. (E)-2-(3-Bromophenyl)-3-(4-methanesulfonylphenyl)acrylic acid (9h), and compounds having 4-(4-isopropyloxyphenyl-, 2,4-difluorophenyl-, or 4-methylsulfonylphenyl)phenyl moieties at the acrylic acid C-2 position (11a,b,d), were particularly potent COX-2 inhibitors with a high COX-2 selectivity index (COX-2 IC50 approximately 0.32 microM, SI > 316) similar to the reference drug rofecoxib (COX-2 IC50 = 0.5 microM, SI > 200). Acrylic acid analogs with a C-2 4-hydoxyphenyl (9d, IC50 = 0.56 microM), or 4-acetamidophenyl (9g, IC50 = 0.11 microM), substituent were particularly potent 5-LOX inhibitors that may participate in an additional specific hydrogen-bonding interaction. A number of compounds possessing a C-2 substituted-phenyl moiety (4-Br, 4-F, and 4-OH), or a 4- or 3-(2,4-difluorophenyl)phenyl moiety, showed potent 15-LOX inhibitory activity (IC50 values in the 0.31-0.49 microM range) relative to the reference drug luteolin (IC50 = 3.2 microM). Compounds having a C-2 4-acetylaminophenyl, or 4-(2,4-difluorophenyl)phenyl, moiety exhibited anti-inflammatory activities that were equipotent to aspirin, but less than that of celecoxib. The structure-activity data acquired indicate the acrylic acid moiety constitutes a suitable scaffold (template) to design novel acyclic dual inhibitors of the COX and LOX isozymes.

Replacement of the dihydroquinolinone pharmacophore of Zeneca's ZD2138 by ionizable imidazolylphenyl moiety has lead to the discovery of a novel series of potent and orally active 5-lipoxygenase (5-LO) inhibitors. The synthesis and structure-activity relationship (SAR) of this series of compounds are described herein.

Azorella compacta, Azorella yareta and Laretia acaulis (Apiaceae) are native species from the high Andes Mountains, northeastern Chile, and they have being traditionally used to treat asthma, colds and bronchitis, illnesses with inflammation and pain as the main symptoms. Interestingly, there are no scientific reports available on their benefits or toxicity. This study was carried out with the purpose of validating the medicinal use of these species and to discover anti-inflammatory and analgesic new molecules. As a working hypothesis, we have proposed that these medicinal species contain bioactive compounds with anti-inflammatory and analgesic effects. In this context, azorellanol, 13-hydroxy-7-oxoazorellane and 7-deacetylazorellanol, three diterpenoids previously isolated only from these plants, were subjected to farmaco-toxicological evaluation. Their topical anti-inflammatory and analgesic activities along with acute toxicities or innocuosness were also investigated. Our results indicate the absence of toxic and side effects in mice. All compounds presented dose-related inhibition of pain. 13-hydroxy-7-oxoazorellane was the most potent analgesic but it was less effective than sodium naproxen, the reference drug. Azorellanol exhibited the highest topical anti-inflammatory potency on AA (arachidonic acid) and TPA (12-deoxyphorbol 13-tetradecanoate) induced oedema, and it effect was similar to the reference drugs (nimesulide and indomethacin). Probably, its mechanism of action could be explained through the inhibition to cyclo-oxygenase activity. Our results corroborate the anti-inflammatory and analgesic effects of these species, and it justifies their use in folk medicine.

(5Z,8Z,11Z,13E)-15-Hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE) is not well oxygenated by arachidonate 15-lipoxygenases because of two structural reasons: (i) it contains a hydrophilic OH-group in close proximity to its methyl end and (ii) it lacks the bisallylic methylene at C(13). We synthesized racemic (5Z,8Z,11Z,14Z)-16-hydroxy-5,8,11,14-eicosatetraenoic acid (16-HETE) which still contains the bisallylic C(13), separated the enantiomers reaching an optical purity of >99% and tested them as substrates for 5- and 15-lipoxygenases. Our synthetic pathway, which is based on stereospecific hydrogenation of a polyacetylenic precursor, yielded substantial amounts (30%) of 14,15-dehydro-16-HETE in addition to 16-HETE. When 16-HETE was tested as lipoxygenase substrate, we found that it is well oxygenated by the soybean 15-lipoxygenase and by the recombinant human 5-lipoxygenase. Analysis of the reaction products suggested an arachidonic acid-like alignment at the active site of the two enzymes. In contrast, the product pattern of 16-HETE methyl ester oxygenation by the soybean lipoxygenase (5-lipoxygenation) may be explained by an inverse head to tail substrate orientation.

Three polyhydroxy-2-phenylnaphthalenes (1-3) and the oxy analogue of tetrahydroxypavinan (4) were prepared and evaluated for their antioxidant properties (inhibition of diphenylpycrylhydrazyl radical (DPPH), reduction of iron (III) ion) and inhibition of 5-lipoxygenase (5-LO) activity. Their three-dimensional structures were established on the basis of spectroscopic data and semiempirical calculations. Compounds 1 and 2 were found as potent 5-LO inhibitors as nordihydroguaiaretic acid (NDGA), whereas 4 is 2.5 times less potent than NDGA. The reliability of the 3-D structures with the 5-LO inhibition properties is discussed. Their antioxidant properties show that tested compounds are expected to act as redox inhibitors.

Series of 6-aminoalkyloxazolo[4,5-b]pyridin-2(3H)-ones incorporating structural modifications both in the alkyl chain and basic amino moiety were tested for their analgesic efficacy and safety in mice and rats. Two of the synthesised compounds, 4a (3-methyl-6-[(4-phenyl-1-piperazinyl)methyl]oxazolo[4,5-b]pyridin-2(3H)-one) and 12a (3-methyl-6¿1-[2-(4-phenyl-1-piperazinyl)ethan-1-ol]¿oxazolo[4,5-b]pyridin- 2(3H)-one) were found to be more potent than aspirin with ED50 values of 26 (16.1-42.4) and 15.5 (11.4-21.2) mg/kg po (mouse, phenylquinone writhing test) respectively and 6 (3.1-9.8) and 5.5 (3.5-8.8) mg/kg po (rat, acetic acid writhing test). Compounds 4a and 12a proved to be potent nonopioid nonantiinflammatory analgesics but unfortunately have sedative properties at relatively low doses (respectively 64 and 16 mg/kg po, mice).

Compound 4k N-[5-(4-fluoro)phenoxythien-2-yl]methanesulfonamide is representative of a new class of potent inhibitors of 5-lipoxygenase (5-LO). These versatile compounds exhibit dose-dependent inhibition of 5-LO with IC50s ranging from 20-100 nM in the rat basophilic leukemia (RBL-1) cell homogenate assay and submicromolar IC50s in both the RBL-1 and human peripheral blood leukocyte (PBL) whole cell assays. Compound 4k also showed significant anti-inflammatory activity in the adjuvant arthritic rat at an oral dose of 3 mg/kg.

A series of substituted indolylalkoxyiminoalkylcarboxylates were found to be potent leukotriene biosynthesis inhibitors. The structure-activity relationships were investigated. Representative potent inhibitors identified were the quinolyl 3a (A-86885) and pyridyl 3b (A-86886) congeners with in vitro IC50s of 21 and 9 nM and in vivo leukotriene inhibition in the rat with oral ED50s of 0.9 and 1.7 mg/kg, respectively.

2-Phenylsulfenyl- (1b), 2-phenylselenenyl- (1c) and 2-phenyltellurenyl-1-naphthol (1d) were prepared and their antioxidative properties evaluated in comparison with 2-benzyl-1-naphthol (1a; DuP 654). 2-Phenyltellurenyl-1-naphthol had a significantly lower (1.00 V versus SCE) oxidation potential than the other three compounds (1.24, 1.27 and 1.25 V, respectively, versus SCE for compounds 1a, 1b and 1c) as determined by cyclic voltammetry. In contrast to the other materials, compound 1d was able to catalyze the reduction of hydrogen peroxide in the presence of thiols as stoichiometric reducing agents. The organotellurium compound was also the most efficient inhibitor of azo-initiated peroxidation of linoleic acid in a two-phase model system. Ab initio geometry optimization at the 3-21G(*) level revealed infinitesimal changes in the molecular conformations of the carbon, sulfur, selenium and tellurium analogues. As judged by their ability to inhibit stimulated LTB4 biosynthesis in human neutrophils, compounds 1a-1d all turned out to be highly potent 5-lipoxygenase inhibitors with IC50-values ranging from 0.40 microM for 2-benzyl-1-naphthol (1a) to 0.063 microM for 2-phenyltellurenyl-1-naphthol (1d).