Activation and inhibition of leukotriene A4 hydrolase aminopeptidase activity by diphenyl ether and derivatives

Design, Synthesis, Antifungal Activity, and Molecular Docking Studies of Novel Chiral Isoxazoline-Benzofuran-Sulfonamide Derivatives

Succinate dehydrogenase (SDH) is one of the most important molecular targets for the development of novel fungicides. With the emerging problem of resistance in plant fungal pathogens, novel compounds with high fungicidal activity need to be developed, but the study of chiral pesticides for the inhibition of highly destructive plant pathogens has been rarely reported in recent years. Therefore, a series of novel chiral isoxazoline-benzofuran-sulfonamide derivatives were designed to investigate potential novel antifungal molecules. The chiral target compound 3a was cultured as a single crystal and confirmed using X-ray diffraction. All the target compounds were tested for antifungal activity, and compounds 3c, 3i, 3s, and 3r were found to have significant antifungal effects against S. sclerotiorum with EC50 values of 0.42 mg/L, 0.33 mg/L, 0.37 mg/L, and 0.40 mg/L, respectively, which were superior to the commercial fungicide fluopyram (EC50 = 0.47 mg/L). The IC50 value of compound 3i against the SDH of S. sclerotiorum was 0.63 mg/mL, which was further demonstrated by enzyme activity assays. Scanning electron microscopy showed that 3i had a significant inhibitory effect on S. sclerotiorum. In addition, the fluorescence quenching analysis assay indicated that compound 3i had a similar effect with the positive control fluopyram. Molecular docking exhibited that target compounds with chiral configuration had better affinity than racemic configuration, and 3i possessed stronger action than fluopyram, which was in keeping with the in vitro test results. These results would provide a basis and reference for the development of novel chiral fungicides.

Modulation of the 5-Lipoxygenase Pathway by Chalcogen-Containing Inhibitors of Leukotriene A4 Hydrolase

The 5-lipoxygenase (5-LOX) pathway gives rise to bioactive inflammatory lipid mediators, such as leukotrienes (LTs). 5-LOX carries out the oxygenation of arachidonic acid to the 5-hydroperoxy derivative and then to the leukotriene A₄ epoxide which is converted to a chemotactic leukotriene B₄ (LTB₄) by leukotriene A₄ hydrolase (LTA₄H). In addition, LTA₄H possesses aminopeptidase activity to cleave the N-terminal proline of a pro-inflammatory tripeptide, prolyl-glycyl-proline (PGP). Based on the structural characteristics of LTA₄H, it is possible to selectively inhibit the epoxide hydrolase activity while sparing the inactivating, peptidolytic, cleavage of PGP. In the current study, chalcogen-containing compounds, 4-(4-benzylphenyl) thiazol-2-amine (ARM1) and its selenazole (TTSe) and oxazole (TTO) derivatives were characterized regarding their inhibitory and binding properties. All three compounds selectively inhibit the epoxide hydrolase activity of LTA₄H at low micromolar concentrations, while sparing the aminopeptidase activity. These inhibitors also block the 5-LOX activity in leukocytes and have distinct inhibition constants with recombinant 5-LOX. Furthermore, high-resolution structures of LTA₄H with inhibitors were determined and potential binding sites to 5-LOX were proposed. In conclusion, we present chalcogen-containing inhibitors which differentially target essential steps in the biosynthetic route for LTB₄ and can potentially be used as modulators of inflammatory response by the 5-LOX pathway.

Substrate-dependent modulation of the leukotriene A4 hydrolase aminopeptidase activity and effect in a murine model of acute lung inflammation

The aminopeptidase activity (AP) of the leukotriene A4 hydrolase (LTA4H) enzyme has emerged as a therapeutic target to modulate host immunity. Initial reports focused on the benefits of augmenting the LTA4H AP activity and clearing its putative pro-inflammatory substrate Pro-Gly-Pro (PGP). However, recent reports have introduced substantial complexity disconnecting the LTA4H modulator 4-methoxydiphenylmethane (4MDM) from PGP as follows: (1) 4MDM inhibits PGP hydrolysis and subsequently inhibition of LTA4H AP activity, and (2) 4MDM activates the same enzyme target in the presence of alternative substrates. Differential modulation of LTA4H by 4MDM was probed in a murine model of acute lung inflammation, which showed that 4MDM modulates the host neutrophilic response independent of clearing PGP. X-ray crystallography showed that 4MDM and PGP bind at the zinc binding pocket and no allosteric binding was observed. We then determined that 4MDM modulation is not dependent on the allosteric binding of the ligand, but on the N-terminal side chain of the peptide. In conclusion, our study revealed that a peptidase therapeutic target can interact with its substrate and ligand in complex biochemical mechanisms. This raises an important consideration when ligands are designed to explain some of the unpredictable outcomes observed in therapeutic discovery targeting LTA4H.

Fluorescent probes for visualizing ROS-associated proteins in disease

Abnormal expression of proteins, including catalytic and expression dysfunction, is directly related to the development of various diseases in living organisms. Reactive oxygen species (ROS) could regulate protein expression by redox modification or cellular signal pathway and thus influence the development of disease. Determining the expression level and activity of these ROS-associated proteins is of considerable importance in early-stage disease diagnosis and the identification of new drug targets. Fluorescence imaging technology has emerged as a powerful tool for specific in situ imaging of target proteins by virtue of its non-invasiveness, high sensitivity and good spatiotemporal resolution. In this review, we summarize advances made in the past decade for the design of fluorescent probes that have contributed to tracking ROS-associated proteins in disease. We envision that this review will attract significant attention from a wide range of researchers in their utilization of fluorescent probes for in situ investigation of pathological processes synergistically regulated by both ROS and proteins.

Classification and QSAR models of leukotriene A4 hydrolase (LTA4H) inhibitors by machine learning methods

Leukotriene A4 hydrolase (LTA4H) is an important anti-inflammatory target which can convert leukotriene A4 (LTA4) into pro-inflammatory substance leukotriene B4 (LTB4). In this paper, we built 18 classification models for 463 LTA4H inhibitors by using support vector machine (SVM), random forest (RF) and K-Nearest Neighbour (KNN). The best classification model (Model 2A) was built from RF and MACCS fingerprints. The prediction accuracy of 88.96% and the Matthews correlation coefficient (MCC) of 0.74 had been achieved on the test set. We also divided the 463 LTA4H inhibitors into six subsets using K-Means. We found that the highly active LTA4H inhibitors mostly contained diphenylmethane or diphenyl ether as the scaffold and pyridine or piperidine as the side chain. In addition, six quantitative structure-activity relationship (QSAR) models for 172 LTA4H inhibitors were built by multiple linear regression (MLR) and SVM. The best QSAR model (Model 6A) was built by using SVM and CORINA Symphony descriptors. The coefficients of determination of the training set and the test set were equal to 0.81 and 0.79, respectively. Classification and QSAR models could be used for subsequent virtual screening, and the obtained fragments that were important for highly active inhibitors would be helpful for designing new LTA4H inhibitors.

Expedient Discovery for Novel Antifungal Leads Targeting Succinate Dehydrogenase: Pyrazole-4-formylhydrazide Derivatives Bearing a Diphenyl Ether Fragment

The pyrazole-4-carboxamide scaffold containing a flexible amide chain has emerged as the molecular skeleton of highly efficient agricultural fungicides targeting succinate dehydrogenase (SDH). Based on the above vital structural features of succinate dehydrogenase inhibitors (SDHI), three types of novel pyrazole-4-formylhydrazine derivatives bearing a diphenyl ether moiety were rationally conceived under the guidance of a virtual docking comparison between bioactive molecules and SDH. Consistent with the virtual verification results of a molecular docking comparison, the in vitro antifungal bioassays indicated that the skeleton structure of title compounds should be optimized as an N'-(4-phenoxyphenyl)-1H-pyrazole-4-carbohydrazide scaffold. Strikingly, N'-(4-phenoxyphenyl)-1H-pyrazole-4-carbohydrazide derivatives 11o against Rhizoctonia solani, 11m against Fusarium graminearum, and 11g against Botrytis cinerea exhibited excellent antifungal effects, with corresponding EC₅₀ values of 0.14, 0.27, and 0.52 μg/mL, which were obviously better than carbendazim against R. solani (0.34 μg/mL) and F. graminearum (0.57 μg/mL) as well as penthiopyrad against B. cinerea (0.83 μg/mL). The relative studies on an in vivo bioassay against R. solani, bioactive evaluation against SDH, and molecular docking were further explored to ascertain the practical value of compound 11o as a potential fungicide targeting SDH. The present work provided a non-negligible complement for the structural optimization of antifungal leads targeting SDH.

The enzymology of human eicosanoid pathways: the lipoxygenase branches

Eicosanoids are short-lived derivatives of polyunsaturated fatty acids that serve as autocrine and paracrine signaling molecules. They are involved numerous biological processes of both the well state and disease states. A thorough understanding of the progression the disease state and homeostasis of the well state requires a complete evaluation of the systems involved. This review examines the enzymology for the enzymes involved in the production of eicosanoids along the lipoxygenase branches of the eicosanoid pathways with particular emphasis on those derived from arachidonic acid. The enzymatic parameters, protocols to measure them, and proposed catalytic mechanisms are presented in detail.

Effect of Modifier Structure on the Activation of Leukotriene A4 Hydrolase Aminopeptidase Activity

Activation of the leukotriene A4 hydrolase (LTA4H) aminopeptidase (AP) activity with 4-methoxydiphenylmethane (4MDM) promoted resolution of neutrophil infiltration in a murine cigarette smoke-induced model for emphysematous chronic obstructive pulmonary disease. Recently, 4-(4-benzylphenyl)thiazol-2-amine (ARM1) was published as a ligand for LTA4H with potential anti-inflammatory properties. To investigate the effect of modifier structure on enzyme kinetics of LTA4H, a series of analogues bearing structural features of ARM1 and 4MDM were synthesized using trifluoroborate Suzuki coupling reactions. Following, the 2.8 Å X-ray crystal structure of LTA4H complexed with 4-OMe-ARM1, a 4MDM-ARM1 hybrid molecule, was determined. Kinetic analysis showed that ARM1 and related analogues lowered affinity for the enzyme-substrate complex, resulting in a change of mechanism from hyperbolic mixed predominately catalytic activation (HMx(Sp < Ca)A) as observed for 4MDM to a predominately specific activation (HMx(Sp > Ca)A) mechanism. 4-OMe-ARM1 was then shown to dose responsively reduce LTB4 production in human neutrophils.

Activation of Glutathione Peroxidase 4 as a Novel Anti-inflammatory Strategy

The anti-oxidative enzyme, glutathione peroxidase 4 (GPX4), helps to promote inflammation resolution by eliminating oxidative species produced by the arachidonic acid (AA) metabolic network. Up-regulating its activity has been proposed as a promising strategy for inflammation intervention. In the present study, we aimed to study the effect of GPX4 activator on the AA metabolic network and inflammation related pathways. Using combined computational and experimental screen, we identified a novel compound that can activate the enzyme activity of GPX4 by more than two folds. We further assessed its potential in a series of cellular assays where GPX4 was demonstrated to play a regulatory role. We are able to show that GPX4 activation suppressed inflammatory conditions such as oxidation of AA and NF-κB pathway activation. We further demonstrated that this GPX4 activator can decrease the intracellular ROS level and suppress ferroptosis. Our study suggests that GPX4 activators can be developed as anti-inflammatory or cyto-protective agent in lipid-peroxidation-mediated diseases.

Novel Allosteric Activators for Ferroptosis Regulator Glutathione Peroxidase 4

Glutathione peroxidase 4 (GPX4) is essential for cell membrane repair, inflammation suppression, and ferroptosis inhibition. GPX4 upregulation provides unique drug discovery opportunities for inflammation and ferroptosis-related diseases. However, rational design of protein activators is challenging. Until now, no compound has been reported to activate the enzyme activity of GPX4. Here, we identified a potential allosteric site in GPX4 and successfully found eight GPX4 activators using a novel computational strategy and experimental studies. Compound 1 from the virtual screen increased GPX4 activity, suppressed ferroptosis, reduced pro-inflammatory lipid mediator production, and inhibited NF-κB pathway activation. Further chemical synthesis and structure-activity relationship studies revealed seven more activators. The strongest compound, 1d4, increased GPX4 activity to 150% at 20 μM in the cell-free assay and 61 μM in cell extracts. Therefore, we demonstrated that GPX4 can be directly activated using chemical compounds to suppress ferroptosis and inflammation. Meanwhile, the discovery of GPX4 activators verified the possibility of rational design of allosteric activators.

Feasibility and physiological relevance of designing highly potent aminopeptidase-sparing leukotriene A4 hydrolase inhibitors

Leukotriene A4 Hydrolase (LTA4H) is a bifunctional zinc metalloenzyme that comprises both epoxide hydrolase and aminopeptidase activity, exerted by two overlapping catalytic sites. The epoxide hydrolase function of the enzyme catalyzes the biosynthesis of the pro-inflammatory lipid mediator leukotriene (LT) B4. Recent literature suggests that the aminopeptidase function of LTA4H is responsible for degradation of the tripeptide Pro-Gly-Pro (PGP) for which neutrophil chemotactic activity has been postulated. It has been speculated that the design of epoxide hydrolase selective LTA4H inhibitors that spare the aminopeptidase pocket may therefore lead to more efficacious anti-inflammatory drugs. In this study, we conducted a high throughput screen (HTS) for LTA4H inhibitors and attempted to rationally design compounds that would spare the PGP degrading function. While we were able to identify compounds with preference for the epoxide hydrolase function, absolute selectivity was not achievable for highly potent compounds. In order to assess the relevance of designing such aminopeptidase-sparing LTA4H inhibitors, we studied the role of PGP in inducing inflammation in different settings in wild type and LTA4H deficient (LTA4H KO) animals but could not confirm its chemotactic potential.  Attempting to design highly potent epoxide hydrolase selective LTA4H inhibitors, therefore seems to be neither feasible nor relevant.

The development of novel LTA4H modulators to selectively target LTB4 generation

The pro-inflammatory mediator leukotriene B₄ (LTB₄) is implicated in the pathologies of an array of diseases and thus represents an attractive therapeutic target. The enzyme leukotriene A₄ hydrolase (LTA₄H) catalyses the distal step in LTB₄ synthesis and hence inhibitors of this enzyme have been actively pursued. Despite potent LTA₄H inhibitors entering clinical trials all have failed to show efficacy. We recently identified a secondary anti-inflammatory role for LTA₄H in degrading the neutrophil chemoattractant Pro-Gly-Pro (PGP) and rationalized that the failure of conventional LTA₄H inhibitors may be that they inadvertently prevented PGP degradation. We demonstrate that these inhibitors do indeed fail to discriminate between the dual activities of LTA₄H, and enable PGP accumulation in mice. Accordingly, we have developed novel compounds that potently inhibit LTB₄ generation whilst leaving PGP degradation unperturbed. These novel compounds could represent a safer and superior class of LTA₄H inhibitors for translation into the clinic.

Diverse ways of perturbing the human arachidonic acid metabolic network to control inflammation

Inflammation and other common disorders including diabetes, cardiovascular disease, and cancer are often the result of several molecular abnormalities and are not likely to be resolved by a traditional single-target drug discovery approach. Though inflammation is a normal bodily reaction, uncontrolled and misdirected inflammation can cause inflammatory diseases such as rheumatoid arthritis and asthma. Nonsteroidal anti-inflammatory drugs including aspirin, ibuprofen, naproxen, or celecoxib are commonly used to relieve aches and pains, but often these drugs have undesirable and sometimes even fatal side effects. To facilitate safer and more effective anti-inflammatory drug discovery, a balanced treatment strategy should be developed at the biological network level. In this Account, we focus on our recent progress in modeling the inflammation-related arachidonic acid (AA) metabolic network and subsequent multiple drug design. We first constructed a mathematical model of inflammation based on experimental data and then applied the model to simulate the effects of commonly used anti-inflammatory drugs. Our results indicated that the model correctly reproduced the established bleeding and cardiovascular side effects. Multitarget optimal intervention (MTOI), a Monte Carlo simulated annealing based computational scheme, was then developed to identify key targets and optimal solutions for controlling inflammation. A number of optimal multitarget strategies were discovered that were both effective and safe and had minimal associated side effects. Experimental studies were performed to evaluate these multitarget control solutions further using different combinations of inhibitors to perturb the network. Consequently, simultaneous control of cyclooxygenase-1 and -2 and leukotriene A4 hydrolase, as well as 5-lipoxygenase and prostaglandin E2 synthase were found to be among the best solutions. A single compound that can bind multiple targets presents advantages including low risk of drug-drug interactions and robustness regarding concentration fluctuations. Thus, we developed strategies for multiple-target drug design and successfully discovered several series of multiple-target inhibitors. Optimal solutions for a disease network often involve mild but simultaneous interventions of multiple targets, which is in accord with the philosophy of traditional Chinese medicine (TCM). To this end, our AA network model can aptly explain TCM anti-inflammatory herbs and formulas at the molecular level. We also aimed to identify activators for several enzymes that appeared to have increased activity based on MTOI outcomes. Strategies were then developed to predict potential allosteric sites and to discover enzyme activators based on our hypothesis that combined treatment with the projected activators and inhibitors could balance different AA network pathways, control inflammation, and reduce associated adverse effects. Our work demonstrates that the integration of network modeling and drug discovery can provide novel solutions for disease control, which also calls for new developments in drug design concepts and methodologies. With the rapid accumulation of quantitative data and knowledge of the molecular networks of disease, we can expect an increase in the development and use of quantitative disease models to facilitate efficient and safe drug discovery.

Role of leukotriene A4 hydrolase aminopeptidase in the pathogenesis of emphysema

The leukotriene A4 hydrolase (LTA4H) is a bifunctional enzyme with epoxy hydrolase and aminopeptidase activities. We hypothesize that the LTA4H aminopeptidase activity alleviates neutrophilic inflammation, which contributes to cigarette smoke (CS)-induced emphysema by clearing proline-glycine-proline (PGP), a triamino acid chemokine known to induce chemotaxis of neutrophils. To investigate the biological contributions made by the LTA4H aminopeptidase activity in CS-induced emphysema, we exposed wild-type mice to CS over 5 mo while treating them with a vehicle or a pharmaceutical agent (4MDM) that selectively augments the LTA4H aminopeptidase without affecting the bioproduction of leukotriene B4. Emphysematous phenotypes were assessed by premortem lung physiology with a small animal ventilator and by postmortem histologic morphometry. CS exposure acidified the airspaces and induced localization of the LTA4H protein into the nuclei of the epithelial cells. This resulted in accumulation of PGP in the airspaces by suppressing the LTA4H aminopeptidase activity. When the LTA4H aminopeptidase activity was selectively augmented by 4MDM, the levels of PGP in the bronchoalveolar lavage fluid and infiltration of neutrophils into the lungs were significantly reduced without affecting the levels of leukotriene B4. This protected murine lungs from CS-induced emphysematous alveolar remodeling. In conclusion, CS exposure promotes the development of CS-induced emphysema by suppressing the enzymatic activities of the LTA4H aminopeptidase in lung tissues and accumulating PGP and neutrophils in the airspaces. However, restoring the leukotriene A4 aminopeptidase activity with a pharmaceutical agent protected murine lungs from developing CS-induced emphysema.

A sensitive fluorigenic substrate for selective in vitro and in vivo assay of leukotriene A4 hydrolase activity

Leukotriene A4 hydrolase (LTA4H) is a bifunctional zinc-dependent metalloprotease bearing both an epoxide hydrolase, producing the pro-inflammatory LTB4 leukotriene, and an aminopeptidase activity, whose physiological relevance has long been ignored. Distinct substrates are commonly used for each activity, although none is completely satisfactory; LTA4, substrate for the hydrolase activity, is unstable and inactivates the enzyme, whereas aminoacids β-naphthylamide and para-nitroanilide, used as aminopeptidase substrates, are poor and nonselective. Based on the three-dimensional structure of LTA4H, we describe a new, specific, and high-affinity fluorigenic substrate, PL553 [L-(4-benzoyl)phenylalanyl-β-naphthylamide], with both in vitro and in vivo applications. PL553 possesses a catalytic efficiency (k(cat)/K(m)) of 3.8±0.5×10⁴ M⁻¹ s⁻¹ using human recombinant LTA4H and a limit of detection and quantification of less than 1 to 2 ng. The PL553 assay was validated by measuring the inhibitory potency of known LTA4H inhibitors and used to characterize new specific amino-phosphinic inhibitors. The LTA4H inhibition measured with PL553 in mouse tissues, after intravenous administration of inhibitors, was also correlated with a reduction in LTB4 levels. This authenticates the assay as the first allowing the easy measurement of endogenous LTA4H activity and in vitro specific screening of new LTA4H inhibitors.

Development of predictive quantitative structure–activity relationship model and its application in the discovery of human leukotriene A4 hydrolase inhibitors

Background: Human LTA4H catalyzes the conversion of LTA4 to LTB4 and plays a key role in innate immune responses. Inhibition of this enzyme can be a valid method in the treatment of inflammatory response exhibited through LTB4. Results & discussion: The quantitative structure–activity relationship (QSAR) models were developed using genetic function approximation and validated. A training set of 26 diverse compounds and their molecular descriptors were used to develop highly correlating QSAR models. A six-descriptor model explaining the biological activity of the training and test sets with correlation values of 0.846 and 0.502, respectively, was selected as the best model and used in a database screening of drug-like Maybridge database followed by molecular docking. Conclusion: Based on the predicted potent inhibitory activities, expected binding mode and molecular interactions at the active site of hLTA4H final leads were selected as to be utilized in designing future hLTA4H inhibitors.

Leukotriene A4 Hydrolase: Biology, Inhibitors and Clinical Applications

Leukotriene A4 hydrolase is a zinc-containing cytosolic enzyme with both hydrolase and aminopeptidase activity. LTA4H stereospecifically catalyzes the transformation of the unstable epoxide LTA4 to the potent pro-inflammatory mediator LTB4. Variations in the lta4h gene have been linked to susceptibility to multiple diseases including myocardial infarction, stroke and asthma. Pre-clinical animal models and human biomarker data have implicated LTB4 in inflammatory diseases. Several groups have now identified selective inhibitors of LTA4H, many of which were influenced by the disclosure of a protein crystal structure a decade ago. Clinical validation of LTA4H remains elusive despite the progression of inhibitors into pre-clinical and clinical development.

Molecular dynamics simulation study and hybrid pharmacophore model development in human LTA4H inhibitor design

Human leukotriene A4 hydrolase (hLTA4H) is a bi-functional enzyme catalyzes the hydrolase and aminopeptidase functions upon the fatty acid and peptide substrates, respectively, utilizing the same but overlapping binding site. Particularly the hydrolase function of this enzyme catalyzes the rate-limiting step of the leukotriene (LT) cascade that converts the LTA4 to LTB4. This product is a potent pro-inflammatory activator of inflammatory responses and thus blocking this conversion provides a valuable means to design anti-inflammatory agents. Four structurally very similar chemical compounds with highly different inhibitory profile towards the hydrolase function of hLTA4H were selected from the literature. Molecular dynamics (MD) simulations of the complexes of hLTA4H with these inhibitors were performed and the results have provided valuable information explaining the reasons for the differences in their biological activities. Binding mode analysis revealed that the additional thiophene moiety of most active inhibitor helps the pyrrolidine moiety to interact the most important R563 and K565 residues. The hLTA4H complexes with the most active compound and substrate were utilized in the development of hybrid pharmacophore models. These developed pharmacophore models were used in screening chemical databases in order to identify lead candidates to design potent hLTA4H inhibitors. Final evaluation based on molecular docking and electronic parameters has identified three compounds of diverse chemical scaffolds as potential leads to be used in novel and potent hLTA4H inhibitor design.

Microsomal prostaglandin E synthase-1 exhibits one-third-of-the-sites reactivity

mPGES-1 (microsomal prostaglandin E synthase-1) is a newly recognized target for the treatment of inflammatory diseases. As the terminal enzyme of the prostaglandin production pathway, mPGES-1 inhibition may have a low risk of side effects. Inhibitors of mPGES-1 have attracted considerable attention as next-generation anti-inflammatory drugs. However, as mPGES-1 is a membrane protein, its enzymatic mechanism remains to be disclosed fully. We used MD (molecular dynamics) simulations, mutation analysis, hybrid experiments and co-IP (co-immunoprecipitation) to investigate the conformation transitions of mPGES-1 during catalysis. mPGES-1 forms a homotrimer with three substrate-binding sites (pockets). In the MD simulation, only one substrate molecule could bind to one of the pockets and form the active complex, suggesting that the mPGES-1 trimer has only one pocket active at any given time. This one-third-of-the-sites reactivity enzyme mechanism was verified further by hybridization experiments and MD simulations. The results of the present study revealed for the first time a novel one-third-of-the-sites reactivity enzyme mechanism for mPGES-1, and the unique substrate-binding pocket in our model constituted an active conformation that was suitable for further enzymatic mechanism study and structural-based drug design against mPGES-1.

Effect of the leukotriene A4 hydrolase aminopeptidase augmentor 4-methoxydiphenylmethane in a pre-clinical model of pulmonary emphysema

The leukotriene A(4) hydrolase enzyme is a dual functioning enzyme with the following two catalytic activities: an epoxide hydrolase function that transforms the lipid metabolite leukotriene A(4) to leukotriene B(4) and an aminopeptidase function that hydrolyzes short peptides. To date, all drug discovery efforts have focused on the epoxide hydrolase activity of the enzyme, because of extensive biological characterization of the pro-inflammatory properties of its metabolite, leukotriene B(4). Herein, we have designed a small molecule, 4-methoxydiphenylmethane, as a pharmacological agent that is bioavailable and augments the aminopeptidase activity of the leukotriene A(4) hydrolase enzyme. Pre-clinical evaluation of our drug showed protection against intranasal elastase-induced pulmonary emphysema in murine models.