Discovery and Biological Evaluation of a Novel Class of Dual Microsomal Prostaglandin E2 Synthase-1/5-lipoxygenase Inhibitors Based on 2-[(4,6-Diphenethoxypyrimidin-2-yl)thio]hexanoic Acid

Clinical data mining reveals analgesic effects of lapatinib in cancer patients

Microsomal prostaglandin E2 synthase 1 (mPGES-1) is recognized as a promising target for a next generation of anti-inflammatory drugs that are not expected to have the side effects of currently available anti-inflammatory drugs. Lapatinib, an FDA-approved drug for cancer treatment, has recently been identified as an mPGES-1 inhibitor. But the efficacy of lapatinib as an analgesic remains to be evaluated. In the present clinical data mining (CDM) study, we have collected and analyzed all lapatinib-related clinical data retrieved from clinicaltrials.gov. Our CDM utilized a meta-analysis protocol, but the clinical data analyzed were not limited to the primary and secondary outcomes of clinical trials, unlike conventional meta-analyses. All the pain-related data were used to determine the numbers and odd ratios (ORs) of various forms of pain in cancer patients with lapatinib treatment. The ORs, 95% confidence intervals, and P values for the differences in pain were calculated and the heterogeneous data across the trials were evaluated. For all forms of pain analyzed, the patients received lapatinib treatment have a reduced occurrence (OR 0.79; CI 0.70–0.89; P = 0.0002 for the overall effect). According to our CDM results, available clinical data for 12,765 patients enrolled in 20 randomized clinical trials indicate that lapatinib therapy is associated with a significant reduction in various forms of pain, including musculoskeletal pain, bone pain, headache, arthralgia, and pain in extremity, in cancer patients. Our CDM results have demonstrated the significant analgesic effects of lapatinib, suggesting that lapatinib may be repurposed as a novel type of analgesic.

Research developments in the syntheses, anti-inflammatory activities and structure-activity relationships of pyrimidines

Pyrimidines are aromatic heterocyclic compounds that contain two nitrogen atoms at positions 1 and 3 of the six-membered ring. Numerous natural and synthetic pyrimidines are known to exist. They display a range of pharmacological effects including antioxidants, antibacterial, antiviral, antifungal, antituberculosis, and anti-inflammatory. This review sums up recent developments in the synthesis, anti-inflammatory effects, and structure-activity relationships (SARs) of pyrimidine derivatives. Numerous methods for the synthesis of pyrimidines are described. Anti-inflammatory effects of pyrimidines are attributed to their inhibitory response versus the expression and activities of certain vital inflammatory mediators namely prostaglandin E2, inducible nitric oxide synthase, tumor necrosis factor-α, nuclear factor κB, leukotrienes, and some interleukins. Literature studies reveal that a large number of pyrimidines exhibit potent anti-inflammatory effects. SARs of numerous pyrimidines have been discussed in detail. Several possible research guidelines and suggestions for the development of new pyrimidines as anti-inflammatory agents are also given. Detailed SAR analysis and prospects together provide clues for the synthesis of novel pyrimidine analogs possessing enhanced anti-inflammatory activities with minimum toxicity.

DREAM-in-CDM Approach and Identification of a New Generation of Anti-inflammatory Drugs Targeting mPGES-1

Microsomal prostaglandin E2 synthase-1 (mPGES-1) is known as an ideal target for next generation of anti-inflammatory drugs without the side effects of currently available anti-inflammatory drugs. However, there has been no clinically promising mPGES-1 inhibitor identified through traditional drug discovery and development route. Here we report a new approach, called DREAM-in-CDM (Drug Repurposing Effort Applying Integrated Modeling-in vitro/vivo-Clinical Data Mining), to identify an FDA-approved drug suitable for use as an effective analgesic targeting mPGES-1. The DREAM-in-CDM approach consists of three steps: computational screening of FDA-approved drugs; in vitro and/or in vivo assays; and clinical data mining. By using the DREAM-in-CDM approach, lapatinib has been identified as a promising mPGES-1 inhibitor which may have significant anti-inflammatory effects to relieve various forms of pain and possibly treat various inflammation conditions involved in other inflammation-related diseases such as the lung inflammation caused by the newly identified COVID-19. We anticipate that the DREAM-in-CDM approach will be used to repurpose FDA-approved drugs for various new therapeutic indications associated with new targets.

Molecular mechanism of 15-lipoxygenase allosteric activation and inhibition

Human reticulocyte 15-lipoxygenase (15-LOX) plays an important role in inflammation resolution and is also involved in many cancer-related processes. Both an activator and an inhibitor will serve as research tools for understanding the biological functions of 15-LOX and provide opportunities for drug discovery. In a previous study, both allosteric activators and inhibitors of 15-LOX were discovered through a virtual screening based computational approach. However, why molecules binding to the same site causes different effects remains to be disclosed. In the present study, we used previously reported activator and inhibitor molecules as probes to elucidate the mechanism of allosteric regulation of 15-LOX. We measured the influences of the allosteric activator and inhibitor on the enzymatic reaction rate and found that the activator increases 15-LOX activity by preventing substrate inhibition instead of increasing the turnover number. The inhibitor can also prevent substrate inhibition but decreases the turnover number at the same time, resulting in inhibition. Molecular dynamics simulations were conducted to help explain the underlying mechanism of allostery. Both the activator and inhibitor were demonstrated to be able to prevent 15-LOX from transforming into potentially inactive conformations. Compared to the activator, the inhibitor molecule restrains the motions of residues around the substrate binding site and reduces the flexibility of 15-LOX. These results explained the different effects between the activator and the inhibitor and shed light on how to effectively design novel activator molecules.

Structure-based discovery of mPGES-1 inhibitors suitable for preclinical testing in wild-type mice as a new generation of anti-inflammatory drugs

Human mPGES-1 is recognized as a promising target for next generation of anti-inflammatory drugs without the side effects of currently available anti-inflammatory drugs, and various inhibitors have been reported in the literature. However, none of the reported potent inhibitors of human mPGES-1 has shown to be also a potent inhibitor of mouse or rat mPGES-1, which prevents using the well-established mouse/rat models of inflammation-related diseases for preclinical studies. Hence, despite of extensive efforts to design and discover various human mPGES-1 inhibitors, the promise of mPGES-1 as a target for the next generation of anti-inflammatory drugs has never been demonstrated in any wild-type mouse/rat model using an mPGES-1 inhibitor. Here we report discovery of a novel type of selective mPGES-1 inhibitors potent for both human and mouse mPGES-1 enzymes through structure-based rational design. Based on in vivo studies using wild-type mice, the lead compound is indeed non-toxic, orally bioavailable, and more potent in decreasing the PGE₂ (an inflammatory marker) levels compared to the currently available drug celecoxib. This is the first demonstration in wild-type mice that mPGES-1 is truly a promising target for the next generation of anti-inflammatory drugs.

Structure-based discovery of mPGES-1 inhibitors suitable for preclinical testing in wild-type mice as a new generation of anti-inflammatory drugs

Human mPGES-1 is recognized as a promising target for next generation of anti-inflammatory drugs without the side effects of currently available anti-inflammatory drugs, and various inhibitors have been reported in the literature. However, none of the reported potent inhibitors of human mPGES-1 has shown to be also a potent inhibitor of mouse or rat mPGES-1, which prevents using the well-established mouse/rat models of inflammation-related diseases for preclinical studies. Hence, despite of extensive efforts to design and discover various human mPGES-1 inhibitors, the promise of mPGES-1 as a target for the next generation of anti-inflammatory drugs has never been demonstrated in any wild-type mouse/rat model using an mPGES-1 inhibitor. Here we report discovery of a novel type of selective mPGES-1 inhibitors potent for both human and mouse mPGES-1 enzymes through structure-based rational design. Based on in vivo studies using wild-type mice, the lead compound is indeed non-toxic, orally bioavailable, and more potent in decreasing the PGE₂ (an inflammatory marker) levels compared to the currently available drug celecoxib. This is the first demonstration in wild-type mice that mPGES-1 is truly a promising target for the next generation of anti-inflammatory drugs.

Natural products as inhibitors of prostaglandin E2 and pro-inflammatory 5-lipoxygenase-derived lipid mediator biosynthesis

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit prostanoid formation and represent prevalent therapeutics for treatment of inflammatory disorders. However, NSAIDs are afflicted with severe side effects, which might be circumvented by more selective suppression of pro-inflammatory eicosanoid biosynthesis. This concept led to dual inhibitors of microsomal prostaglandin E₂ synthase (mPGES)-1 and 5-lipoxygenase that are crucial enzymes in the biosynthesis of pro-inflammatory prostaglandin E₂ and leukotrienes. The potential of their dual inhibition in light of superior efficacy and safety is discussed. Focus is placed on natural products, for which direct inhibition of mPGES-1 and leukotriene biosynthesis has been confirmed.

Multiple target-centric strategy to tame inflammation

Single-target inhibition is an unsatisfactory therapeutic option to treat multifactorial pathologies, brought into limelight 'paradox of inflammation' beside dearth of innovation, rationalizes a shift toward 'multiple-target' design concept in anti-inflammatory research field. To improvise, two platform strategies, drugs mixture or multitarget drugs, are plausible. Dual cyclooxygenase/lipoxygenase inhibitor 'licofelone' developed after the backfire of rofecoxib due to safety concerns has fetched first light of triumph of the latter strategy. As hitting multiple targets in restraint is perhaps more viable strategy rather than single target, this review, outlines the most germane multiple target agents of synthetic and natural origin placing clear advantage in favors of multitarget strategy as real therapeutic solution for inflammation.

Selective inhibitors of human mPGES-1 from structure-based computational screening

Human mPGES-1 is recognized as a promising target for next generation of anti-inflammatory drugs. Although various mPGES-1 inhibitors have been reported in literature, few have entered clinical trials and none has been proven clinically useful so far. It is highly desired for developing the next generation of therapeutics for inflammation-related diseases to design and discover novel inhibitors of mPGES-1 with new scaffolds. Here, we report the identification of a series of new, potent and selective inhibitors of human mPGES-1 with diverse scaffolds through combined computational and experimental studies. The computationally modeled binding structures of these new inhibitors of mPGES-1 provide some interesting clues for rational design of modified structures of the inhibitors to more favorably bind with mPGES-1.

Computational models for the classification of mPGES-1 inhibitors with fingerprint descriptors

Human microsomal prostaglandin [Formula: see text] synthase (mPGES)-1 is a promising drug target for inflammation and other diseases with inflammatory symptoms. In this work, we built classification models which were able to classify mPGES-1 inhibitors into two groups: highly active inhibitors and weakly active inhibitors. A dataset of 1910 mPGES-1 inhibitors was separated into a training set and a test set by two methods, by a Kohonen's self-organizing map or by random selection. The molecules were represented by different types of fingerprint descriptors including MACCS keys (MACCS), CDK fingerprints, Estate fingerprints, PubChem fingerprints, substructure fingerprints and 2D atom pairs fingerprint. First, we used a support vector machine (SVM) to build twelve models with six types of fingerprints and found that MACCS had some advantage over the other fingerprints in modeling. Next, we used naïve Bayes (NB), random forest (RF) and multilayer perceptron (MLP) methods to build six models with MACCS only and found that models using RF and MLP methods were better than NB. Finally, all the models with MACCS keys were used to make predictions on an external test set of 41 compounds. In summary, the models built with MACCS keys and using SVM, RF and MLP methods show good prediction performance on the test sets and the external test set. Furthermore, we made a structure-activity relationship analysis between mPGES-1 and its inhibitors based on the information gain of fingerprints and could pinpoint some key functional groups for mPGES-1 activity. It was found that highly active inhibitors usually contained an amide group, an aromatic ring or a nitrogen heterocyclic ring, and several heteroatoms substituents such as fluorine and chlorine. The carboxyl group and sulfur atom groups mainly appeared in weakly active inhibitors.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Chemistry and biology of microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors as novel anti-inflammatory agents: recent developments and current status

Prostaglandin (PG) E₂, a key mediator of inflammatory pain and fever, is biosynthesized from PGH₂ by mPGES-1.

Pirinixic acids: flexible fatty acid mimetics with various biological activities

Pirinixic acid is a typical fatty acid mimetic and was developed as synthetic antihyperlipidemic agent. While its target remained unknown in the early development, it has later been characterized as dual PPARα/γ agonist. Based on this activity, pirinixic acid has served as a lead compound for several structure–activity relationship (SAR) studies addressing diverse targets for lipid mimetics. Many structural variants of pirinixic acid descendants have been developed and thereby potent agents on metabolic, inflammatory and neuroprotective targets were discovered of which some have proven in vivo efficacy. This article reviews pirinixic acid descendants along with their in vitro-pharmacological profiles, summarizes their in vivo data and finally gives a future perspective for this valuable class of fatty acid mimetics.

Perspective of microsomal prostaglandin E2 synthase-1 as drug target in inflammation-related disorders

Prostaglandin (PG)E2 encompasses crucial roles in pain, fever, inflammation and diseases with inflammatory component, such as cancer, but is also essential for gastric, renal, cardiovascular and immune homeostasis. Cyclooxygenases (COX) convert arachidonic acid to the intermediate PGH2 which is isomerized to PGE2 by at least three different PGE2 synthases. Inhibitors of COX - non-steroidal anti-inflammatory drugs (NSAIDs) - are currently the only available therapeutics that target PGE2 biosynthesis. Due to adverse effects of COX inhibitors on the cardiovascular system (COX-2-selective), stomach and kidney (COX-1/2-unselective), novel pharmacological strategies are in demand. The inducible microsomal PGE2 synthase (mPGES)-1 is considered mainly responsible for the excessive PGE2 synthesis during inflammation and was suggested as promising drug target for suppressing PGE2 biosynthesis. However, 15 years after intensive research on the biology and pharmacology of mPGES-1, the therapeutic value of mPGES-1 as drug target is still vague and mPGES-1 inhibitors did not enter the market so far. This commentary will first shed light on the structure, mechanism and regulation of mPGES-1 and will then discuss its biological function and the consequence of its inhibition for the dynamic network of eicosanoids. Moreover, we (i) present current strategies for interfering with mPGES-1-mediated PGE2 synthesis, (ii) summarize bioanalytical approaches for mPGES-1 drug discovery and (iii) describe preclinical test systems for the characterization of mPGES-1 inhibitors. The pharmacological potential of selective mPGES-1 inhibitor classes as well as dual mPGES-1/5-lipoxygenase inhibitors is reviewed and pitfalls in their development, including species discrepancies and loss of in vivo activity, are discussed.

Targeting microsomal prostaglandin E2synthase-1 (mPGES-1): the development of inhibitors as an alternative to non-steroidal anti-inflammatory drugs (NSAIDs)

AA cascade and several key residues in the 3D structure of mPGES-1.

SAR-studies of γ-secretase modulators with PPARγ-agonistic and 5-lipoxygenase-inhibitory activity for Alzheimer's disease

We present the design, synthesis and biological evaluation of compounds containing a 2-(benzylidene)hexanoic acid scaffold as multi-target directed γ-secretase-modulators. Broad structural variations were undertaken to elucidate the structure-activity-relationships at the 5-position of the aromatic core. Compound 13 showed the most potent activity profile with IC50 values of 0.79μM (Aβ42), 0.3μM (5-lipoxygenase) and an EC50 value of 4.64μM for PPARγ-activation. This derivative is the first compound exhibiting low micromolar to nanomolar activities for these three targets. Combining γ-secretase-modulation, PPARγ-agonism and inhibition of 5-lipoxygenase in one compound could be a novel disease-modifying multi-target-strategy for Alzheimer's disease to concurrently address the causative amyloid pathology and secondary pathologies like chronic brain inflammation.

Discovery of depsides and depsidones from lichen as potent inhibitors of microsomal prostaglandin E2 synthase-1 using pharmacophore models

Nature in silico: Virtual screening using validated pharmacophore models identified lichen depsides and depsidones as potential inhibitors of mPGES-1, an emerging target for NSAIDs. Evaluation of the virtual hits in a cell-free assay revealed physodic acid and perlatolic acid as potent inhibitors of mPGES-1 (IC(50) = 0.4 and 0.43 μM, respectively), indicating that these natural products have potential as novel anti-inflammatory agents.

Microsomal Prostaglandin E2 Synthase-1

The prostanoids and leukotrienes (LTs) formed from arachidonic acid (AA) via the cyclooxygenase (COX)-1/2 and 5-lipoxygenase (5-LO) pathway, respectively, mediate inflammatory responses, chronic tissue remodelling, cancer, asthma and autoimmune disorders, but also possess homeostatic functions in the gastrointestinal tract, uterus, brain, kidney, vasculature and host defence. Based on the manifold functions of these eicosanoids, the clinical use of non-steroidal anti-inflammatory drugs (NSAIDs), a class of drugs that block formation of all prostanoids, is hampered by severe side-effects including gastrointestinal injury, renal irritations and cardiovascular risks. Therefore, anti-inflammatory agents interfering with eicosanoid biosynthesis require a well-balanced pharmacological profile to minimize these on-target side-effects. Current anti-inflammatory research aims at identifying compounds that can suppress the massive formation of pro-inflammatory prostaglandin (PG)E2 without affecting homeostatic PGE2 and PGI2 synthesis. The inducible microsomal prostaglandin E2 synthase-1 (mPGES-1) is one promising target enzyme. We will give an overview about the structure, regulation and function of mPGES-1 and then present novel inhibitors of mPGES-1 that may possess a promising pharmacological profile.

Structure-activity relationship of nonacidic quinazolinone inhibitors of human microsomal prostaglandin synthase 1 (mPGES 1)

Microsomal prostaglandin E synthase 1 (mPGES-1) is a key enzyme of the arachidonic acid cascade. Its product PGE(2) plays an important role in various inflammatory processes, pain, fever, and cancer. Selective inhibition of mPGES-1 might be a promising step to avoid cyclooxygenase-related effects of NSAIDs. We studied a class of quinazolinone derivatives of the lead structure FR20 for their effects on the isolated human and murine enzymes, human HeLa cells, and in various settings of the whole blood assay. Novel compounds with direct enzyme inhibiting activity in the submicromolar range (IC(50): 0.13-0.37 μM) were designed using a bioisosteric replacement strategy and proved to be effective in both cells and human whole blood. Furthermore, pharmacological profiling of toxicity and eicosanoid screening with LC/MS-MS was applied to characterize this new class of mPGES-1 inhibitors.

Identification and development of mPGES-1 inhibitors: where we are at?

Microsomal prostaglandin E synthase-1 (mPGES-1) is the terminal synthase responsible for the synthesis of the pro-tumorigenic prostaglandin E(2) (PGE(2)). mPGES-1 is overexpressed in a wide variety of cancers. Since its discovery in 1997 by Bengt Samuelsson and collaborators, the enzyme has been the object of over 200 peer-reviewed articles. Although today mPGES-1 is considered a validated and promising therapeutic target for anticancer drug discovery, challenges in inhibitor design and selectivity are such that up to this date there are only a few published records of small-molecule inhibitors targeting the enzyme and exhibiting some in vivo anticancer activity. This review summarizes the structures, and the in vitro and in vivo activities of these novel mPGES-1 inhibitors. Challenges that have been encountered are also discussed.

SAR studies of acidic dual γ-secretase/PPARγ modulators

A novel set of dual γ-secretase/PPARγ modulators characterized by a 2-benzyl hexanoic acid scaffold is presented. Synthetic efforts were focused on the variation of the substitution pattern of the central benzene. Finally, we obtained a new class of 2,5-disubstituted 2-benzylidene hexanoic acid derivatives, which act as dual γ-secretase/PPARγ modulators in the low micromolar range. We have explored broad SAR and successfully improved the dual pharmacological activity and the selectivity profile against potential off-targets such as NOTCH and COX. Compound 17 showed an IC(50) Aβ42=2.4 μM and an EC(50) PPARγ=7.2 μM and could be a valuable tool to further evaluate the concept of dual γ-secretase/PPARγ modulators in animal models of Alzheimer's disease.