Licofelone suppresses prostaglandin E2 formation by interference with the inducible microsomal prostaglandin E2 synthase-1

Furazanopyrazine-based novel promising anticancer agents interfering with the eicosanoid biosynthesis pathways by dual mPGES-1 and sEH inhibition

We report the identification of a new set of compounds based on the furazanopyrazine core interfering with eicosanoid biosynthesis and acting as potentially effective anti-inflammatory and anticancer agents. Based on our previous promising results on a set of furazanopyrazine-based compounds against the microsomal prostaglandin E2 synthase-1 (mPGES-1) enzyme, we here identified derivatives with improved pharmacokinetic properties by replacing the ester moiety with a more stable ether group. A focused virtual library of 1 × 104 molecules was built and screened against mPGES-1 through molecular docking experiments, leading to the selection of 10 candidates for synthesis and biological evaluation. Several molecules were found to inhibit mPGES-1 and, among them, two items featured IC50 values in the low micromolar range. Additional computational studies on the collection of synthesized compounds demonstrated that compound 3b, previously emerged as an mPGES-1 inhibitor, interfered with soluble epoxide hydrolase (sEH) activity, thus emerging as a valuable dual mPGES-1/sEH inhibitor. The pharmacokinetic features of the most potent compounds were accurately estimated. Unfortunately, poor outcomes were obtained for 3b; on the other hand, compound 7e exhibited promising mPGES-1 inhibition and excellent pharmacokinetic profile, demonstrating that the novel furazanopyrazine-based items with ether moiety possess improved pharmacokinetic properties compared to the ester-based compounds reported in our previous study. Additionally, the anticancer properties of 7e and 7d, the latter emerged as the most active mPGES-1 inhibitor, were evaluated and both compounds showed promising activities against HCT-116 human colorectal cancer (CRC) cells. These findings highlight the furazanopyrazine core as a promising scaffold for disclosing new anti-inflammatory drugs with the ability to inhibit targets belonging to arachidonic acid cascade.

Discovery of novel microsomal prostaglandin E2 synthase 1 (mPGES-1) inhibitors by a structurally inspired virtual screening study

Prostaglandin (PG) E2 is a pro-inflammatory lipid mediator derived from the metabolism of arachidonic acid (AA) by cyclooxygenases (COX) and PGE2 synthases. Nonsteroidal anti-inflammatory drugs (NSAIDs), commonly used in the treatment of inflammation, nonselectively inhibit COX activity and decrease PGE2 production. However, these drugs cause gastrointestinal bleeding and several cardiovascular complications. Therefore, inhibiting microsomal PGE2 Synthase-1 (mPGES-1) to block PGE2 production downstream of COX is expected to yield safer and more effective treatments for inflammation, cancer, and cardiovascular diseases. At present, there are no mPGES-1 inhibitors available on the market, but ongoing research continuously evaluates new compounds in both preclinical and clinical stages. Here, we conducted a high throughput virtual screening campaign to discover novel mPGES-1 inhibitor scaffolds. This campaign utilized physicochemical filtering alongside both structure-aware ligand-based approaches (shape screening templates and pharmacophore models, which were generated based on the 3D binding modes of the co-crystallized mPGES-1 inhibitors) and structure-based strategies (refinement with docking and molecular dynamics). Thirty-four compounds were selected and biologically tested for mPGES-1 inhibition in a cell-free assay using microsomes from interleukin-1β-stimulated A549 cells as the source of mPGES-1. The most potent compound inhibited the remaining enzyme activity with an IC50 value of 6.46 μM in a cell-free assay for PGE2 production. We also compared the binding patterns of the most active compounds identified in this study with those of co-crystallized inhibitors using molecular dynamics simulations. This comparison underscored the crucial role of ionic interactions, π-π interactions, hydrogen bonds, and water bridges involving specific amino acids. Our results highlight the importance of these interaction networks within the binding cavity in various binding scenarios. Ultimately, the insights gained from this study could assist in designing and developing new mPGES-1 inhibitors.

2-Phenylbenzothiazoles featuring heteroaryl sulfonamide end-capping substructures as developable mPGES-1 inhibitors

The inhibition of human microsomal prostaglandin E2 (PGE2) synthase-1 (mPGES-1) is a promising therapeutic modality for developing next-generation anti-inflammatory medications. In this study, we present novel 2-phenylbenzothiazole derivatives featuring heteroaryl sulfonamide end-capping substructures as inhibitors of human mPGES-1, with IC50 values in the range of 0.72-3.40 µM in a cell-free assay of PGE2 formation. Notably, compound 21, featuring a quinoxalinedione ring in its sulfonamide segment, effectively suppresses PGE2 biosynthesis at a low micromolar concentration (IC50 = 0.72 µM) with exceptional selectivity against cyclooxygenase (COX)-1, COX-2, 5-lipoxygenase (5-LOX), and FLAP. This compound offers a novel chemical scaffold for developing safer and more effective anti-inflammatory agents.

5-methyl-2-carboxamidepyrrole-based novel dual mPGES-1/sEH inhibitors as promising anticancer candidates

Inhibiting microsomal prostaglandin E2 synthase-1 (mPGES-1), an inducible enzyme involved in prostaglandin E2 (PGE2) biosynthesis and tumor microenvironment (TME) homeostasis, is a valuable strategy for treating inflammation and cancer. In this work, 5-methylcarboxamidepyrrole-based molecules were designed and synthesized as new compounds targeting mPGES-1. Remarkably, compounds 1f, 2b, 2c, and 2d were able to significantly reduce the activity of the isolated enzyme, showing IC50 values in the low micromolar range. With the aim of further profiling the synthesized molecules, their ability to interfere with the activity of soluble epoxide hydrolase (sEH), whose inhibition blocks the loss of the anti-inflammatory mediators epoxyeicosatrienoic acids (EETs or epoxyicosatrienoic acids), was investigated in silico and by employing specific biological assays. Among the set of tested compounds, 1f, 2b, 2c, and 2d emerged as mPGES-1/sEH dual inhibitors. Moreover, given that overexpression of mPGES-1 has been observed in many human tumors, we finally explored the biological effect of our compounds in an in vitro model of human colorectal cancer (CRC). The obtained outcomes pave the way for future investigation to optimize and further characterize anticancer pharmacological profile of the carboxamidepyrrole-based molecules.

Novel Benzimidazole Derivatives as Potent Inhibitors of Microsomal Prostaglandin E2 Synthase 1 for the Potential Treatment of Inflammation, Pain, and Fever

Microsomal prostaglandin E2 synthase 1 (mPGES-1) is a promising target for treating inflammatory diseases and pain. This study introduces a novel series of benzimidazoles, with the most potent analogs exhibiting IC50 values of 0.27-7.0 nM in a cell-free assay for prostaglandin (PG)E2 production. Compound 44 (AGU654) demonstrated remarkable selectivity for mPGES-1 (IC50 = 2.9 nM) over COX-1, COX-2, 5-LOX, and FLAP, along with excellent bioavailability. Metabololipidomics analysis with activated human monocyte-derived macrophages and human whole blood revealed that AGU654 selectively suppresses PGE2 production triggered by bacterial exotoxins while sparing other prostaglandins. Furthermore, in vivo studies showed that AGU654 significantly alleviated fever, inflammation, and inflammatory pain in preclinical guinea pig models, suggesting that it could be an effective strategy for managing inflammatory diseases. In conclusion, these benzimidazole derivatives warrant further exploration into new and alternative analogs, potentially uncovering novel compounds with a favorable pharmacological profile possessing significant anti-inflammatory and analgesic properties.

Novel 1,3,4-oxadiazole derivatives as highly potent microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors

Selective inhibition of microsomal prostaglandin E2 synthase-1 (mPGES-1) is implicated as a new therapeutic modality for the development of new-generation anti-inflammatory drugs. Here, we present the discovery of new and potent inhibitors of human mPGES-1, i.e., compounds 13, 15-25, 29-30 with IC50 values in the range of 5.6-82.3 nM in a cell-free assay of prostaglandin (PG)E2 formation. We also demonstrate that 20 (TG554, IC50 = 5.6 nM) suppresses leukotriene (LT) biosynthesis at low µM concentrations, providing a benchmark compound that dually intervenes with inflammatory PGE2 and LT biosynthesis. Comprehensive lipid mediator (LM) metabololipidomics with activated human monocyte-derived macrophages showed that TG554 selectively inhibits inflammatory PGE2 formation over all cyclooxygenase (COX)-derived prostanoids, does not cause substrate shunting towards 5-lipoxygenase (5-LOX) pathway, and does not interfere with the biosynthesis of the specialized pro-resolving mediators as observed with COX inhibitors, providing a new chemotype for effective and safer anti-inflammatory drug development.

Design and synthesis of new dihydropyrimidine/sulphonamide hybrids as promising anti-inflammatory agents via dual mPGES-1/5-LOX inhibition

A novel series of dihydropyrimidine/sulphonamide hybrids 3a-j with anti-inflammatory properties have been developed and tested as dual mPGES-1/5-LOX inhibitors. In vitro assay, results showed that compounds 3c, 3e, 3h, and 3j were the most effective dual inhibitors of mPGES-1 and 5-LOX activities. Compound 3j was the most potent dual inhibitor with IC50 values of 0.92 µM and 1.98 µM, respectively. In vivo, anti-inflammatory studies demonstrated that compounds 3c, 3e, 3h, and 3e had considerable anti-inflammatory activity, with EI% ranging from 29% to 71%. Compounds 3e and 3j were equivalent to celecoxib after the first hour but exhibited stronger anti-inflammatory effects than celecoxib after the third and fifth hours. Moreover, compounds 3e and 3j significantly reduced the levels of pro-inflammatory cytokines (PGE2, TNF-α, and IL-6) with gastrointestinal safety profiles. Molecular docking simulations explored the most potent derivatives' binding affinities and interaction patterns within mPGES-1 and 5-LOX active sites. This study disclosed that compound 3j is a promising anti-inflammatory lead with dual mPGES-1/5-LOX inhibition that deserves further preclinical investigation.

Identification of selective 5-LOX and FLAP inhibitors as novel anti-inflammatory agents by ligand-based virtual screening

Inflammation is a multifaceted biological process in which the conversion of arachidonic acid to eicosanoids, including prostaglandins and leukotrienes (LTs), plays a crucial role. 5-Lipoxygenase (5-LOX) is a key enzyme in cellular LT biosynthesis, and it is supported by the accessory protein 5-lipoxygenase-activating protein (FLAP). Pharmacological interventions to modulate LTs aim at either decreasing their biosynthesis or at mitigating their biological effects. Therefore, inhibiting 5-LOX or FLAP represents a useful strategy to reduce inflammation. Herein we present the identification and pharmacological evaluation of novel inhibitors targeting 5-LOX or FLAP. By means of a ligand-based virtual screening approach, we selected 38 compounds for in vitro assays. Among them, ALR-38 exhibits direct 5-LOX inhibition, while ALR-6 and ALR-27 showed potential as FLAP inhibitors. These latter not only reduced LT production but also promoted the generation of specialized pro-resolving mediators in specific human macrophage phenotypes. Interestingly, the identified compounds turned out to be selective for their respective targets, as none of them displayed activity towards microsomal prostaglandin E2 synthase-1 and soluble epoxide hydrolase, which are other proteins involved in eicosanoid biosynthesis. Thus, these compounds are endowed with potential therapeutic utility in mitigating inflammatory responses and might offer a venue for tackling inflammation-based disorders.

Cannabidiol acts as molecular switch in innate immune cells to promote the biosynthesis of inflammation-resolving lipid mediators

Cannabinoids are phytochemicals from cannabis with anti-inflammatory actions in immune cells. Lipid mediators (LM), produced from polyunsaturated fatty acids (PUFA), are potent regulators of the immune response and impact all stages of inflammation. How cannabinoids influence LM biosynthetic networks is unknown. Here, we reveal cannabidiol (CBD) as a potent LM class-switching agent that stimulates the production of specialized pro-resolving mediators (SPMs) but suppresses pro-inflammatory eicosanoid biosynthesis. Detailed metabololipidomics analysis in human monocyte-derived macrophages showed that CBD (i) upregulates exotoxin-stimulated generation of SPMs, (ii) suppresses 5-lipoxygenase (LOX)-mediated leukotriene production, and (iii) strongly induces SPM and 12/15-LOX product formation in resting cells by stimulation of phospholipase A2-dependent PUFA release and through Ca2+-independent, allosteric 15-LOX-1 activation. Finally, in zymosan-induced murine peritonitis, CBD increased SPM and 12/15-LOX products and suppressed pro-inflammatory eicosanoid levels in vivo. Switching eicosanoid to SPM production is a plausible mode of action of CBD and a promising inflammation-resolving strategy.

Highly potent and selective 5-lipoxygenase inhibition by new, simple heteroaryl-substituted catechols for treatment of inflammation

5-Lipoxygenase (LO) catalyzes the first steps in the formation of pro-inflammatory leukotrienes (LT) that are pivotal lipid mediators contributing to allergic reactions and inflammatory disorders. Based on its key role in LT biosynthesis, 5-LO is an attractive drug target, demanding for effective and selective inhibitors with efficacy in vivo, which however, are still rare. Encouraged by the recent identification of the catechol 4-(3,4-dihydroxyphenyl)dibenzofuran 1 as 5-LO inhibitor, simple structural modifications were made to yield even more effective and selective catechol derivatives. Within this new series, the two most potent compounds 3,4-dihydroxy-3'-phenoxybiphenyl (6b) and 2-(3,4-dihydroxyphenyl)benzo[b]thiophene (6d) potently inhibited human 5-LO in cell-free (IC506b and 6d = 20 nM) and cell-based assays (IC506b = 70 nM, 6d = 60 nM). Inhibition of 5-LO was reversible, unaffected by exogenously added substrate arachidonic acid, and not primarily mediated via radical scavenging and antioxidant activities. Functional 5-LO mutants expressed in HEK293 cells were still prone to inhibition by 6b and 6d, and docking simulations revealed distinct binding of the catechol moiety to 5-LO at an allosteric site. Analysis of 5-LO nuclear membrane translocation and intracellular Ca2+ mobilization revealed that these 5-LO-activating events are hardly affected by the catechols. Importantly, the high inhibitory potency of 6b and 6d was confirmed in human blood and in a murine zymosan-induced peritonitis model in vivo. Our results enclose these novel catechol derivatives as highly potent, novel type inhibitors of 5-LO with high selectivity and with marked effectiveness under pathophysiological conditions.

Identification of 2-Aminoacyl-1,3,4-thiadiazoles as Prostaglandin E2 and Leukotriene Biosynthesis Inhibitors

The application of a multi-step scientific workflow revealed an unprecedented class of PGE₂/leukotriene biosynthesis inhibitors with in vivo activity. Specifically, starting from a combinatorial virtual library of ∼4.2 × 10⁵ molecules, a small set of compounds was identified for the synthesis. Among these, four novel 2-aminoacyl-1,3,4-thiadiazole derivatives (3, 6, 7, and 9) displayed marked anti-inflammatory properties in vitro by strongly inhibiting PGE₂ biosynthesis, with IC₅₀ values in the nanomolar range. The hit compounds also efficiently interfered with leukotriene biosynthesis in cell-based systems and modulated IL-6 and PGE₂ biosynthesis in a lipopolysaccharide-stimulated J774A.1 macrophage cell line. The most promising compound 3 showed prominent in vivo anti-inflammatory activity in a mouse model, with efficacy comparable to that of dexamethasone, attenuating zymosan-induced leukocyte migration in mouse peritoneum with considerable modulation of the levels of typical pro-/anti-inflammatory cytokines.

Rotational constriction of curcuminoids impacts 5-lipoxygenase and mPGES-1 inhibition and evokes a lipid mediator class switch in macrophages

Polypharmacological targeting of lipid mediator networks offers potential for efficient and safe anti-inflammatory therapy. Because of the diversity of its biological targets, curcumin (1a) has been viewed as a privileged structure for bioactivity or, alternatively, as a pan-assay interference (PAIN) compound. Curcumin has actually few high-affinity targets, the most remarkable ones being 5-lipoxygenase (5-LOX) and microsomal prostaglandin E2 synthase (mPGES)-1. These enzymes are critical for the production of pro-inflammatory leukotrienes and prostaglandin (PG)E2, and previous structure-activity-relationship studies in this area have focused on the enolized 1,3-diketone motif, the alkyl-linker and the aryl-moieties, neglecting the rotational state of curcumin, which can adopt twisted conformations in solution and at target sites. To explore how the conformation of curcuminoids impacts 5-LOX and mPGES-1 inhibition, we have synthesized rotationally constrained analogues of the natural product and its pyrazole analogue by alkylation of the linker and/or of the ortho aromatic position(s). These modifications strongly impacted 5-LOX and mPGES-1 inhibition and their systematic analysis led to the identification of potent and selective 5-LOX (3b, IC50 = 0.038 µM, 44.7-fold selectivity over mPGES-1) and mPGES-1 inhibitors (2f, IC50 = 0.11 µM, 4.6-fold selectivity over 5-LOX). Molecular docking experiments suggest that the C2-methylated pyrazolocurcuminoid 3b targets an allosteric binding site at the interface between catalytic and regulatory 5-LOX domain, while the o, o'-dimethylated desmethoxycurcumin 2f likely binds between two monomers of the trimeric mPGES-1 structure. Both compounds trigger a lipid mediator class switch from pro-inflammatory leukotrienes to PG and specialized pro-resolving lipid mediators in activated human macrophages.

In Silico, In Vitro, and In Vivo Analysis of Tanshinone IIA and Cryptotanshinone from Salvia miltiorrhiza as Modulators of Cyclooxygenase-2/mPGES-1/Endothelial Prostaglandin EP3 Pathway

Tanshinone IIA (TIIA) and cryptotanshinone (CRY) from Salvia miltiorrhiza Bunge were investigated for their inhibitory activity against the cyclooxygenase-2 (COX-2)/microsomal prostaglandin E synthase-1 (mPGES-1)/endothelial prostaglandin 3 (EP3) pathway using in silico, in vitro, in vivo, and ex vivo assays. From the analysis of the docking poses, both diterpenoids were able to interact significantly with COX-2, 5-lipoxygenase (5-LO), platelet-activating factor receptor (PAFR), and mPGES-1. This evidence was further corroborated by data obtained from a cell-free assay, where CRY displayed a significant inhibitory potency against mPGES-1 (IC50 = 1.9 ± 0.4 µM) and 5-LO (IC50 = 7.1 µM), while TIIA showed no relevant inhibition of these targets. This was consistent with their activity to increase mice bleeding time (CRY: 2.44 ± 0.13 min, p ≤ 0.001; TIIA: 2.07 ± 0.17 min p ≤ 0.01) and with the capability to modulate mouse clot retraction (CRY: 0.048 ± 0.011 g, p ≤ 0.01; TIIA: 0.068 ± 0.009 g, p ≤ 0.05). For the first time, our results show that TIIA and, in particular, CRY are able to interact significantly with the key proteins involved not only in the onset of inflammation but also in platelet activity (and hyper-reactivity). Future preclinical and clinical investigations, together with this evidence, could provide the scientific basis to consider these compounds as an alternative therapeutic approach for thrombotic- and thromboembolic-based diseases.

Licofelone, a potent COX/5-LOX inhibitor and a novel option for treatment of neurological disorders

Neurological disorders result in disability and morbidity. Neuroinflammation is a key factor involved in progression or resolution of a series of neurological disorders like Huntington disease (HD), Parkinson's disease (PD), Alzheimer's disease (AD), Spinal Cord Injury (SCI), and Seizure. Thereby, anti-inflammatory drugs have been developed to improve the neurodegenerative impairments. Licofelone is an approved osteoarthritis drug that inhibits both the COX (cyclooxygenase) and 5-LOX (lipoxygenase) pathways. Licofelone has pain-relieving and anti-inflammatory effects and it was shown to have neuroprotective properties in the central nervous system, which is implicated in its regulatory effect on the COX/5-LOX pathway, inflammatory cytokines, and immune responses. In this study, we briefly review the various features of neurological disorders and the function of COX/LOX in their flare up and current pharmacological products for their management. Moreover, this review attempts to summarize potential therapeutics that target the immune responses within the central nervous system. A better understanding of the interactions between Licofelone and the nervous systems will be crucial to demonstrate the possible efficacy of Licofelone in neurological disorders.

Microsomal prostaglandin E2 synthase-1 and its inhibitors: Molecular mechanisms and therapeutic significance

Inflammation is closely linked to the abnormal phospholipid metabolism chain of cyclooxygenase-2/microsomal prostaglandin E₂ synthase-1/prostaglandin E₂ (COX-2/mPGES-1/PGE₂). In clinical practice, non-steroidal anti-inflammatory drugs (NSAIDs) as upstream COX-2 enzyme activity inhibitors are widely used to block COX-2 cascade to relieve inflammatory response. However, NSAIDs could also cause cardiovascular and gastrointestinal side effects due to its inhibition on other prostaglandins generation. To avoid this, targeting downstream mPGES-1 instead of upstream COX is preferable to selectively block overexpressed PGE₂ in inflammatory diseases. Some mPGES-1 inhibitor candidates including synthetic compounds, natural products and existing anti-inflammatory drugs have been proved to be effective in in vitro experiments. After 20 years of in-depth research on mPGES-1 and its inhibitors, ISC 27864 have completed phase II clinical trial. In this review, we intend to summarize mPGES-1 inhibitors focused on their inhibitory specificity with perspectives for future drug development.

Structure-based screening for the discovery of 1,2,4-oxadiazoles as promising hits for the development of new anti-inflammatory agents interfering with eicosanoid biosynthesis pathways

The multiple inhibition of biological targets involved in pro-inflammatory eicosanoid biosynthesis represents an innovative strategy for treating inflammatory disorders in light of higher efficacy and safety. Herein, following a multidisciplinary protocol involving virtual combinatorial screening, chemical synthesis, and in vitro and in vivo validation of the biological activities, we report the identification of 1,2,4-oxadiazole-based eicosanoid biosynthesis multi-target inhibitors. The multidisciplinary scientific approach led to the identification of three 1,2,4-oxadiazole hits (compounds 1, 2 and 5), all endowed with IC₅₀ values in the low micromolar range, acting as 5-lipoxygenase-activating protein (FLAP) antagonists (compounds 1 and 2), and as a multi-target inhibitor (compound 5) of arachidonic acid cascade enzymes, namely cyclooxygenase-1 (COX-1), 5-lipoxygenase (5-LO) and microsomal prostaglandin E₂ synthase-1 (mPGES-1). Moreover, our in vivo results demonstrate that compound 5 is able to attenuate leukocyte migration in a model of zymosan-induced peritonitis and to modulate the production of IL-1β and TNF-α. These results are of interest for further expanding the chemical diversity around the 1,2,4-oxadiazole central core, enabling the identification of novel anti-inflammatory agents characterized by a favorable pharmacological profile and considering that moderate interference with multiple targets might have advantages in re-adjusting homeostasis.

From Vietnamese plants to a biflavonoid that relieves inflammation by triggering the lipid mediator class switch to resolution

Chronic inflammation results from excessive pro-inflammatory signaling and the failure to resolve the inflammatory reaction. Lipid mediators orchestrate both the initiation and resolution of inflammation. Switching from pro-inflammatory to pro-resolving lipid mediator biosynthesis is considered as efficient strategy to relieve chronic inflammation, though drug candidates exhibiting such features are unknown. Starting from a library of Vietnamese medical plant extracts, we identified isomers of the biflavanoid 8-methylsocotrin-4'-ol from Dracaena cambodiana, which limit inflammation by targeting 5-lipoxygenase and switching the lipid mediator profile from leukotrienes to specialized pro-resolving mediators (SPM). Elucidation of the absolute configurations of 8-methylsocotrin-4'-ol revealed the 2S,γS-isomer being most active, and molecular docking studies suggest that the compound binds to an allosteric site between the 5-lipoxygenase subdomains. We identified additional subordinate targets within lipid mediator biosynthesis, including microsomal prostaglandin E2 synthase-1. Leukotriene production is efficiently suppressed in activated human neutrophils, macrophages, and blood, while the induction of SPM biosynthesis is restricted to M2 macrophages. The shift from leukotrienes to SPM was also evident in mouse peritonitis in vivo and accompanied by a substantial decrease in immune cell infiltration. In summary, we disclose a promising drug candidate that combines potent 5-lipoxygenase inhibition with the favorable reprogramming of lipid mediator profiles.

Discovery of N-amido-phenylsulfonamide derivatives as novel microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors

Our previous research showed that N-carboxy-phenylsulfonyl hydrazide (scaffold A) could reduce LPS-stimulated PGE₂ levels in RAW 264.7 macrophage cells by an inhibition of mPGES-1 enzyme. However, a number of scaffold A derivatives showed the drawbacks such as the formation of regioisomers and poor liver metabolic stability. In order to overcome these synthetic and metabolic problems, therefore, we decided to replace N-carboxy-phenylsulfonyl hydrazide (scaffold A) with N-carboxy-phenylsulfonamide (scaffold B) or N-amido-phenylsulfonamide frameworks (scaffold C) as a bioisosteric replacement. Among them, MPO-0186 (scaffold C) inhibited the production of PGE₂ (IC₅₀: 0.24 μM) in A549 cells via inhibition of mPGES-1 (IC₅₀: 0.49 μM in a cell-free assay) and was found to be approximately 9- and 8-fold more potent than MK-886 as a reference inhibitor, respectively. A molecular docking study theoretically suggests that MPO-0186 could inhibit PGE₂ production by blocking the PGH₂ binding site of mPGES-1 enzyme. Furthermore, MPO-0186 demonstrated good liver metabolic stability and no significant inhibition observed in clinically relevant CYP isoforms except CYP2C19. This result provides a potential starting point for the development of selective and potent mPGES-1 inhibitor with a novel scaffold.

Beneficial Modulation of Lipid Mediator Biosynthesis in Innate Immune Cells by Antirheumatic Tripterygium wilfordii Glycosides

Tripterygium wilfordii glycosides (TWG) is a traditional Chinese medicine with effectiveness against rheumatoid arthritis (RA), supported by numerous clinical trials. Lipid mediators (LM) are biomolecules produced from polyunsaturated fatty acids mainly by cyclooxygenases (COX) and lipoxygenases (LOX) in complex networks which regulate inflammation and immune responses and are strongly linked to RA. The mechanism by which TWG affects LM networks in RA treatment remains elusive. Employing LM metabololipidomics using ultra-performance liquid chromatography-tandem mass spectrometry revealed striking modulation of LM pathways by TWG in human monocyte-derived macrophage (MDM) phenotypes. In inflammatory M1-MDM, TWG (30 µg/mL) potently suppressed agonist-induced formation of 5-LOX products which was confirmed in human PMNL and traced back to direct inhibition of 5-LOX (IC₅₀ = 2.9 µg/mL). TWG also efficiently blocked thromboxane formation in M1-MDM without inhibiting other prostanoids and COX enzymes. Importantly, in anti-inflammatory M2-MDM, TWG (30 µg/mL) induced pronounced formation of specialized pro-resolving mediators (SPM) and related 12/15-LOX-derived SPM precursors, without COX and 5-LOX activation. During MDM polarization, TWG (1 µg/mL) decreased the capacity to generate pro-inflammatory 5-LOX and COX products, cytokines and markers for M1 phenotypes. Together, suppression of pro-inflammatory LM but SPM induction may contribute to the antirheumatic properties of TWG.

Identification of 2-(thiophen-2-yl)acetic Acid-Based Lead Compound for mPGES-1 Inhibition

We report the implementation of our in silico/synthesis pipeline by targeting the glutathione-dependent enzyme mPGES-1, a valuable macromolecular target in both cancer therapy and inflammation therapy. Specifically, by using a virtual fragment screening approach of aromatic bromides, straightforwardly modifiable by the Suzuki-Miyaura reaction, we identified 3-phenylpropanoic acid and 2-(thiophen-2-yl)acetic acid to be suitable chemical platforms to develop tighter mPGES-1 inhibitors. Among these, compounds 1c and 2c showed selective inhibitory activity against mPGES-1 in the low micromolar range in accordance with molecular modeling calculations. Moreover, 1c and 2c exhibited interesting IC₅₀ values on A549 cell lines compared to CAY10526, selected as reference compound. The most promising compound 2c induced the cycle arrest in the G₀/G₁ phase at 24 h of exposure, whereas at 48 and 72 h, it caused an increase of subG₀/G₁ fraction, suggesting an apoptosis/necrosis effect.

Anti-inflammatory celastrol promotes a switch from leukotriene biosynthesis to formation of specialized pro-resolving lipid mediators

The pentacyclic triterpenoid quinone methide celastrol (CS) from Tripterygium wilfordii Hook. F. effectively ameliorates inflammation with potential as therapeutics for inflammatory diseases. However, the molecular mechanisms underlying the anti-inflammatory and inflammation-resolving features of CS are incompletely understood. Here we demonstrate that CS potently inhibits the activity of human 5-lipoxygenase (5-LOX), the key enzyme in pro-inflammatory leukotriene (LT) formation, in cell-free assays with IC₅₀ = 0.19-0.49 µM. Employing metabololipidomics using ultra-performance liquid chromatography coupled to tandem mass spectrometry in activated human polymorphonuclear leukocytes or M1 macrophages we found that CS (1 µM) potently suppresses 5-LOX-derived products without impairing the formation of lipid mediators (LM) formed by 12-/15-LOXs as well as fatty acid substrate release. Intriguingly, CS induced the generation of 12-/15-LOX-derived LM including the specialized pro-resolving mediator (SPM) resolvin D5 in human M2 macrophages. Finally, intraperitoneal pre-treatment of mice with 10 mg/kg CS strongly impaired zymosan-induced LT formation and simultaneously elevated the levels of SPM and related 12-/15-LOX-derived LM in peritoneal exudates, spleen and plasma in vivo. Conclusively, CS promotes a switch from LT biosynthesis to formation of SPM which may underlie the anti-inflammatory and inflammation-resolving effects of CS, representing an interesting pharmacological strategy for intervention with inflammatory disorders.

Simple heteroaryl modifications in the 4,5-diarylisoxazol-3-carboxylic acid scaffold favorably modulates the activity as dual mPGES-1/5-LO inhibitors with in vivo efficacy

Microsomal prostaglandin E₂ synthase-1 (mPGES-1), 5-lipoxygenase (5-LO) and 5- lipoxygenase-activating protein (FLAP) are key for biosynthesis of proinflammatory lipid mediators and pharmacologically relevant drug targets. In the present study, we made an attempt to explore the role of small heteroaromatic fragments on the 4,5-diarylisoxazol-3-carboxylic acid scaffold, which are selected to interact with focused regions in the active sites of mPGES-1, 5-LO and FLAP. We report that the simple structural variations on the benzyloxyaryl side-arm of the scaffold significantly influence the selectivity against mPGES-1, 5-LO and FLAP, enabling to produce multi-target inhibitors of these protein targets, exemplified by compound 18 (IC₅₀ mPGES-1 = 0.16 µM; IC₅₀ 5-LO = 0.39 µM) with in vivo efficacy in animal model of inflammation. The computationally modeled binding structures of these new inhibitors for three targets provide clues for rational design of modified structures as multi-target inhibitors. In conclusion, the simple synthetic procedure, and the possibility of enhancing the potency of this class of inhibitors through structural modifications pave the way for further development of new multi-target inhibitors against mPGES-1, 5-LO and FLAP, with potential application as anti-inflammatory agents.

Overview on the Discovery and Development of Anti-Inflammatory Drugs: Should the Focus Be on Synthesis or Degradation of PGE2?

Inflammation is a protective response that develops against tissue injury and infection. Chronic inflammation, on the other hand, is the key player in the pathogenesis of many inflammatory disorders including cancer. The cytokine storm, an inflammatory response flaring out of control, is mostly responsible for the mortality in COVID-19 patients. Anti-inflammatory drugs inhibit cyclooxygenases (COX), which are involved in the biosynthesis of prostaglandins that promote inflammation. The conventional non-steroidal anti-inflammatory drugs (NSAIDs) are associated with gastric and renal side-effects, as they inhibit both the constitutive COX-1 and the inducible COX-2. The majority of selective COX-2 inhibitors (COXIBs) are without gastric side-effects but are associated with cardiac side-effects on long-term use. The search for anti-inflammatory drugs without side-effects, therefore, has become a dream and ongoing effort of the Pharma companies. As PGE₂ is the key mediator of inflammatory disorders, coming up with a strategy to reduce the levels of PGE₂ alone without affecting other metabolites may form a better choice for the development of next generation anti-inflammatory drugs. In this direction the options being explored are on synthesis of PGE₂-mPGES-1; PGE₂ degradation through a specific PG dehydrogenase, 15-PGDH, and by blocking its activity mediated through a specific PGE receptor, EP4. As leukotrienes formed via the 5-lipoxygenase (5-LOX) pathway also play an important role in the mediation of inflammation, efforts are also being made to target both COX and LOX pathways. This review focuses on addressing the following three points: 1) How NSAIDs and COXIBs are associated with gastric, renal and cardiac side-effects; 2) Should the focus be on the targets upstream or downstream of PGE₂; and 3) the status of alternative targets being explored for the discovery and development of anti-inflammatory drugs without side-effects.

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Discovery and Development of a Novel mPGES-1/5-LOX Dual Inhibitor LFA-9 for Prevention and Treatment of Chronic Inflammatory Diseases

Background

Non-steroidal anti-inflammatory drugs, cyclooxygenase (COX)-2 selective inhibitors, have been explored for prevention and treatment of several inflammatory chronic conditions including arthritis, and cancer. However, the long-term use of these drugs is associated with gastrointestinal, renal, and cardiovascular side effects. Later, COX/5-lipoxygenase (5-LOX) dual inhibitors (eg, licofelone) have been developed but did not enter into the market from the clinical trails due to COX-1/2 inhibition-associated side effects. Hence, targeting microsomal prostaglandin E synthase-1 (mPGES-1) and 5-LOX can be an ideal approach while sparing COX-1/2 activities for development of the next generation of anti-inflammatory drugs with better efficacy and safety.

Materials and Methods

In silico (molecular modelling) studies were used to design a mPGES-1/5-LOX dual inhibitory and COX-1/2 sparing lead molecule licofelone analogue-9 (LFA-9) by modifying the pharmacophore of licofelone. In vitro cell-free enzymatic (mPGES-1, 5-LOX, COX-1/2) assays using fluorometric/colorimetric methods and cell-based assays (LPS-induced PGE₂, LTB₄, and PGI₂ productions from macrophages) using ELISA technique, isothermal calorimetry, and circular dichroism techniques were performed to determine the mPGES-1/5-LOX inhibitory efficacy and selectivity. Anti-inflammatory efficacy of LFA-9 was evaluated using a carrageenan (inflammogen)-induced rat paw edema model. Infiltration/expression of CD68 immune cells and TNF-α in paw tissues were evaluated using confocal microscope and immunoblot analysis. Anti-cancer effect of LFA-9 was evaluated using colon spheroids in vitro.

Results

LFA-9 inhibited mPGES-1/5-LOX and their products PGE₂ and LTB₄, spared COX-1/2 and its product PGI₂. LFA-9 bound strongly with human mPGES-1/5-LOX enzymes and induced changes in their secondary structure, thereby inhibited their enzymatic activities. LFA-9 inhibited carrageenan-induced inflammation (70.4%) in rats and suppressed CD68 immune cell infiltration (P ≤ 0.0001) and TNF-α expression. LFA-9 suppressed colon tumor stemness (60.2%) in vitro through inhibition of PGE₂ (82%) levels.

Conclusion

Overall study results suggest that LFA-9 is a mPGES-1/5-LOX dual inhibitor and showed anti-inflammatory and colorectal cancer preventive activities, and warranted detailed studies.

Structure-based, multi-targeted drug discovery approach to eicosanoid inhibition: Dual inhibitors of mPGES-1 and 5-lipoxygenase activating protein (FLAP)

BACKGROUND

Due to the importance of both prostaglandins (PGs) and leukotrienes (LTs) as pro-inflammatory mediators, and the potential for eicosanoid shunting in the presence of pathway target inhibitors, we have investigated an approach to inhibiting the formation of both PGs and LTs as part of a multi-targeted drug discovery effort.

METHODS

We generated ligand-protein X-ray crystal structures of known inhibitors of microsomal prostaglandin E2 synthase-1 (mPGES-1) and the 5-Lipoxygenase Activating Protein (FLAP), with their respective proteins, to understand the overlapping pharmacophores. We subsequently used molecular modeling and structure-based drug design (SBDD) to identify hybrid structures intended to inhibit both targets.

RESULTS

This work enabled the preparation of compounds 4 and 5, which showed potent in vitro inhibition of both targets.

SIGNIFICANCE

Our findings enhance the structural understanding of mPGES-1 and FLAP's unique ligand binding pockets and should accelerate the discovery of additional dual inhibitors for these two important integral membrane protein drug targets.

Finding New Molecular Targets of Familiar Natural Products Using In Silico Target Prediction

Natural products comprise a rich reservoir for innovative drug leads and are a constant source of bioactive compounds. To find pharmacological targets for new or already known natural products using modern computer-aided methods is a current endeavor in drug discovery. Nature's treasures, however, could be used more effectively. Yet, reliable pipelines for the large-scale target prediction of natural products are still rare. We developed an in silico workflow consisting of four independent, stand-alone target prediction tools and evaluated its performance on dihydrochalcones (DHCs)-a well-known class of natural products. Thereby, we revealed four previously unreported protein targets for DHCs, namely 5-lipoxygenase, cyclooxygenase-1, 17β-hydroxysteroid dehydrogenase 3, and aldo-keto reductase 1C3. Moreover, we provide a thorough strategy on how to perform computational target predictions and guidance on using the respective tools.

Microsomal Prostaglandin E2 Synthase-1 as a New Macromolecular Drug Target in the Prevention of Inflammation and Cancer

BACKGROUND

Cancer is one of the most life-threatening diseases worldwide. Since inflammation is considered to be one of the known characteristics of cancer, the activity of PGE2 has been paired with different tumorigenic steps such as increased tumor cell proliferation, resistance to apoptosis, increased invasiveness, angiogenesis and immunosuppression.

OBJECTIVE

It has been successfully demonstrated that inhibition of mPGES-1 prevented inflammation in preclinical studies. However, despite the crucial roles of mPGEs-1 and PGE2 in tumorigenesis, there is not much in vivo study on mPGES-1 inhibition in cancer therapy. The specificity of mPGEs-1 enzyme and its low expression level under normal conditions makes it a promising drug target with a low risk of side effects.

METHODS

A comprehensive literature search was performed for writing this review. An updated view on PGE2 biosynthesis, PGES isoenzyme family and its pharmacology and the latest information about inhibitors of mPGES-1 have been discussed.

RESULTS

In this study, it was aimed to highlight the importance of mPGES-1 and its inhibition in inflammationrelated cancer and other inflammatory conditions. Information about PGE2 biosynthesis, its role in inflammationrelated pathologies were also provided. We kept the noncancer-related inflammatory part short and tried to bring together promising molecules or scaffolds.

CONCLUSION

The information provided in this review might be useful to researchers in designing novel and potent mPGES-1 inhibitors for the treatment of cancer and inflammation.

A Combinatorial Virtual Screening Approach Driving the Synthesis of 2,4-Thiazolidinedione-Based Molecules as New Dual mPGES-1/5-LO Inhibitors

Dual inhibition of microsomal prostaglandin E₂ synthase-1 (mPGES-1) and 5-lipoxygenase (5-LO), two key enzymes involved in pro-inflammatory eicosanoid biosynthesis, represents a new strategy for treating inflammatory disorders. Herein we report the discovery of 2,4-thiazolidinedione-based mPGES-1/5-LO dual inhibitors following a multidisciplinary protocol, involving virtual combinatorial screening, chemical synthesis, and validation of the biological activities for the selected compounds. Following the multicomponent-based chemical route for the decoration of the 2,4-thiazolidinedione core, a large library of virtual compounds was built (∼2.0×10⁴ items) and submitted to virtual screening. Nine selected molecules were synthesized and biologically evaluated, disclosing among them four compounds able to reduce the activity of both enzymes in the mid- and low- micromolar range of activities. These results are of interest for further expanding the chemical diversity around the 2,4-thiazolidinedione central core, facilitating the identification of novel anti-inflammatory agents endowed with a promising and safer pharmacological profile.

Enantioselective Synthesis of Pyrrolizin-1-ones via Lewis Base Catalyzed N-Allylation of N-Silyl Pyrrole Latent Nucleophiles

Pyrrolizidine alkaloids and their derivatives often feature interesting biological activities. A class of substituted 2,3-dihydro-1H-pyrrolizin-1-one derivatives has been explored as a potential treatment for Alzheimer's disease, but enantioselective synthesis of these molecules is still elusive. We report that enantioselective N-allylation of N-silyl pyrrole latent nucleophiles with allylic fluorides followed by hydrogenation and diastereoselective Friedel-Crafts cyclization constitute an efficient synthetic route to access enantioenriched substituted 2,3-dihydro-1H-pyrrolizin-1-ones.

Structure-Activity Relationships of Pentacyclic Triterpenoids as Inhibitors of Cyclooxygenase and Lipoxygenase Enzymes

Pentacyclic triterpenes may be active agents and provide a rich natural resource of promising compounds for drug development. The inhibitory activities of 29 natural oleanane and ursane pentacyclic triterpenes were evaluated against four major enzymes involved in the inflammatory process: 5-LOX, 15-LOX-2, COX-1, and COX-2. It was found that 3-O-acetyl-β-boswellic acid potently inhibited human 15-LOX-2 (IC₅₀ = 12.2 ± 0.47 μM). Analysis of the structure-activity relationships revealed that the presence of a hydroxy group at position 24 was beneficial in terms of both 5-LOX and COX-1 inhibition. Notably, the introduction of a carboxylic acid group at position 30 was important for dual 5-LOX/COX inhibitory activity; furthermore, its combination with a carbonyl group at C-11 considerably increased 5-LOX inhibition. Also, the presence of an α-hydroxy group at C-2 or a carboxylic acid group at C-23 markedly suppressed the 5-LOX activity. The present findings reveal that the types and configurations of polar moieties at positions C-2, -3, -11, -24, and -30 are important structural aspects of pentacyclic triterpenes for their potential as anti-inflammatory lead compounds.

Discovery of a Celecoxib Binding Site on Prostaglandin E Synthase (PTGES) with a Cleavable Chelation-Assisted Biotin Probe

The coxibs are a subset of nonsteroidal anti-inflammatory drugs (NSAIDs) that primarily target cyclooxygenase-2 (COX-2) to inhibit prostaglandin signaling and reduce inflammation. However, mechanisms to inhibit other members of the prostaglandin signaling pathway may improve selectivity and reduce off-target toxicity. Here, we report a novel binding site for celecoxib on prostaglandin E synthase (PTGES), which is an enzyme downstream of COX-2 in the prostaglandin signaling pathway, using a cleavable chelation-assisted biotin probe 6. Evaluation of the multifunctional probe 6 revealed significantly improved tagging efficiencies attributable to the embedded picolyl functional group. Application of the probe 6 within the small molecule interactome mapping by photoaffinity labeling (SIM-PAL) platform using photo-celecoxib as a reporter for celecoxib identified PTGES and other membrane proteins in the top eight enriched proteins from A549 cells. Four binding sites to photo-celecoxib were mapped by the probe 6, including a binding site with PTGES. The binding interaction with PTGES was validated by competitive displacement with celecoxib and licofelone, which is a known PTGES inhibitor, and was used to generate a structural model of the interaction. The identification of photo-celecoxib interactions with membrane proteins, including the direct binding site on the membrane protein PTGES, will inform further functional followup and the design of new selective inhibitors of the prostaglandin signaling pathway.

A review on mPGES-1 inhibitors: From preclinical studies to clinical applications

Prostaglandin E₂ (PGE₂) is a lipid mediator of inflammation and cancer progression. It is mainly formed via metabolism of arachidonic acid by cyclooxygenases (COX) and the terminal enzyme microsomal prostaglandin E synthase-1 (mPGES-1). Widely used non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX activity, resulting in decreased PGE₂ production and symptomatic relief. However, NSAIDs block the production of many other lipid mediators that have important physiological and resolving actions, and these drugs cause gastrointestinal bleeding and/or increase the risk for severe cardiovascular events. Selective inhibition of downstream mPGES-1 for reduction in only PGE₂ biosynthesis is suggested as a safer therapeutic strategy. This review covers the recent advances in characterization of new mPGES-1 inhibitors in preclinical models and their future clinical applications.

Ginkgolic Acid is a Multi-Target Inhibitor of Key Enzymes in Pro-Inflammatory Lipid Mediator Biosynthesis

Introduction: Lipid mediators (LMs) comprise bioactive metabolites of polyunsaturated fatty acids, including pro-inflammatory prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs), as well as specialized pro-resolving mediators (SPMs). They are essentially biosynthesized via cyclooxygenase (COX) and lipoxygenase (LO) pathways in complex networks and regulate the progression as well as the resolution of inflammatory disorders including inflammation-triggered cancer. Ginkgolic acid (GA) is a phenolic acid contained in Ginkgo biloba L. with neuroprotective, antimicrobial, and antitumoral properties. Although LMs regulate microbial infections and tumor progression, whether GA affects LM biosynthesis is unknown and was investigated here in detail. Methods: Pharmacophore-based virtual screening was performed along with docking simulations. Activity assays were conducted for isolated human recombinant 5-LO, cytosolic phospholipase (PLA)2α, COX-2, and ovine COX-1. The activity of human mPGES-1 and thromboxane A2 synthase (TXAS) was determined in crude cellular fractions. Cellular LM formation was studied using human monocytes, neutrophils, platelets, and M1- and M2-like macrophages. LMs were identified after (ultra)high-performance liquid chromatography by UV detection or ESI-tandem mass spectrometry. Results: GA was identified as virtual hit in an mPGES-1 pharmacophore-based virtual screening. Cell-free assays revealed potent suppression of mPGES-1 activity (IC50 = 0.7 µM) that is fully reversible and essentially independent of the substrate concentration. Moreover, cell-free assays revealed COX-1 and TXAS as additional targets of GA with lower affinity (IC50 = 8.1 and 5.2 µM). Notably, 5-LO, the key enzyme in LT biosynthesis, was potently inhibited by GA (IC50 = 0.2 µM) in a reversible and substrate-independent manner. Docking simulations support the molecular interaction of GA with mPGES-1 and 5-LO and suggest concrete binding sites. Interestingly, interference of GA with mPGES-1, COX-1, TXAS, and 5-LO was evident also in intact cells with IC50 values of 2.1-3.8 µM; no radical scavenging or cytotoxic properties were obvious. Analysis of LM profiles from bacteria-stimulated human M1- and M2-like macrophages confirmed the multi-target features of GA and revealed LM redirection towards the formation of 12-/15-LO products including SPM. Conclusions: We reveal GA as potent multi-target inhibitor of key enzymes in the biosynthesis of pro-inflammatory LMs that contribute to the complex pharmacological and toxicological properties of GA.

5-Lipoxygenase as a drug target: A review on trends in inhibitors structural design, SAR and mechanism based approach

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.

The standardized herbal combination BNO 2103 contained in Canephron® N alleviates inflammatory pain in experimental cystitis and prostatitis

BACKGROUND

Urinary tract infections are among the most common types of infections and give rise to inflammation with pain as one of the main symptoms. The herbal medicinal product Canephron^® N contains BNO 2103, a defined mixture of pulverized rosemary leaves, centaury herb, and lovage root, and has been used in the treatment of urinary tract infections for more than 25 years.

PURPOSE

To test the hypothesis that BNO 2103 reduces pain in cystitis and prostatitis by virtue of anti-inflammatory properties, and to reveal potential mechanisms underlying the anti-inflammatory features.

STUDY DESIGN

BNO 2103 was studied for anti-inflammatory and analgesic properties in three animal models in vivo, and the mode of action underlying the anti-inflammatory features was investigated in human leukocytes and cell-free assays in vitro.

METHODS

To assess the anti-inflammatory and analgesic efficacy of BNO 2103 we employed cyclophosphamide-induced cystitis and carrageenan-induced prostatitis in rats, and zymosan-induced peritonitis in mice. Human neutrophils and monocytes as well as isolated human 5-lipoxygenase and microsomal prostaglandin E₂ synthase-1-containing microsomes were utilized to assess inhibition of leukotriene and/or prostaglandin E₂ production by HPLC and/or ELISA.

RESULTS

When given orally, BNO 2103 reduced inflammation and hyperalgesia in experimental cystitis in rats, while individual components of BNO 2103 also reduced hyperalgesia. Furthermore, BNO 2103 reduced hyperalgesia in rats with carrageenan-induced prostatitis. Cell-based and cell-free studies implicate inhibition of prostaglandin E₂ and leukotriene B₄ biosynthesis as potential mechanisms underlying the analgesic and anti-inflammatory effects.

CONCLUSION

Our data support the hypothesis that BNO 2103 reduces pain by virtue of its anti-inflammatory properties, possibly related to suppression of prostaglandin E₂ and leukotriene B₄ formation, and suggest that this combination has the potential to treat clinical symptoms such as inflammatory pain. Thus BNO 2103 may represent an alternative to reduce the use of antibiotics in urinary tract infections.

Novel benzoxanthene lignans that favorably modulate lipid mediator biosynthesis: A promising pharmacological strategy for anti-inflammatory therapy

Lipid mediators (LM) encompass pro-inflammatory prostaglandins (PG) and leukotrienes (LT) but also specialized pro-resolving mediators (SPM) which display pivotal bioactivities in health and disease. Pharmacological intervention with inflammatory disorders such as osteoarthritis and rheumatoid arthritis commonly employs anti-inflammatory drugs that can suppress PG and LT formation, which however, possess limited effectiveness and side effects. Here, we report on the discovery and characterization of the two novel benzoxanthene lignans 1 and 2 that modulate select LM biosynthetic enzymes enabling the switch from pro-inflammatory LT to SPM biosynthesis as potential pharmacological strategy to intervene with inflammation. In cell-free assays, compound 1 and 2 inhibit microsomal prostaglandin E₂ synthase-1 and leukotriene C₄ synthase (IC₅₀ ∼ 0.6-3.4 µM) and potently interfere with 5-lipoxygenase (5-LOX), the key enzyme in LT biosynthesis (IC₅₀ = 0.04 and 0.09 µM). In human neutrophils, monocytes and M1 and M2 macrophages, compound 1 and 2 efficiently suppress LT biosynthesis (IC₅₀ < 1 µM), accompanied by elevation of 15-LOX-derived LM including SPM. In zymosan-induced murine peritonitis, compound 1 and 2 ameliorated self-limited inflammation along with suppression of early LT formation and elevation of subsequent SPM biosynthesis in vivo. Together, these novel benzoxanthene lignans promote the LM class switch from pro-inflammatory towards pro-resolving LM to terminate inflammation, suggesting their suitability as novel leads for pharmacotherapy of arthritis and related inflammatory disorders.

Synthesis, Biological Evaluation and Structure-Activity Relationships of Diflapolin Analogues as Dual sEH/FLAP Inhibitors

A series of derivatives of the potent dual soluble epoxide hydrolase (sEH)/5-lipoxygenase-activating protein (FLAP) inhibitor diflapolin was designed, synthesized, and characterized by 1H NMR, 13C NMR, and elemental analysis. These novel compounds were biologically evaluated for their inhibitory activity against sEH and FLAP. Molecular modeling tools were applied to analyze structure-activity relationships (SAR) on both targets. Results show that even small modifications on the lead compound diflapolin markedly influence the inhibitory potential, especially on FLAP, suggesting very narrow SAR.

Synthesis of diarylidenecyclohexanone derivatives as potential anti-inflammatory leads against COX-2/mPGES1 and 5-LOX

This study establishes the diarylidenecyclohexanones as good anti-inflammatory pharmacophores with selective high potency against PGE₂and 5-LOX without toxicity towards healthy human cells.

Discovery of 3-hydroxy-3-pyrrolin-2-one-based mPGES-1 inhibitors using a multi-step virtual screening protocol

Targeting microsomal prostaglandin E₂ synthase-1 (mPGES-1) represents an efficient strategy for the development of novel drugs against inflammation and cancer with potentially reduced side effects. With this aim, a virtual screening was performed on a large library of commercially available molecules using the X-ray structure of mPGES-1 co-complexed with a potent inhibitor. Combining fast ligand-based shape alignment, molecular docking experiments, and qualitative analysis of the binding poses, a small set of molecules was selected for the subsequent steps of validation of the biological activity. Compounds 2 and 3, bearing the 3-hydroxy-3-pyrrolin-2-one nucleus, showed mPGES-1-inhibitory activity in the low micromolar range. These data highlighted the applicability of the reported virtual screening protocol for the selection of new mPGES-1 inhibitors as promising anti-inflammatory/anti-cancer drugs.

Melleolides from Honey Mushroom Inhibit 5-Lipoxygenase via Cys159

5-Lipoxygenase (5-LO) initiates the biosynthesis of pro-inflammatory leukotrienes from arachidonic acid, which requires the nuclear membrane-bound 5-LO-activating protein (FLAP) for substrate transfer. Here, we identified human 5-LO as a molecular target of melleolides from honey mushroom (Armillaria mellea). Melleolides inhibit 5-LO via an α,β-unsaturated aldehyde serving as Michael acceptor for surface cysteines at the substrate entrance that are revealed as molecular determinants for 5-LO activity. Experiments with 5-LO mutants, where select cysteines had been replaced by serine, indicated that the investigated melleolides suppress 5-LO product formation via two distinct modes of action: (1) by direct interference with 5-LO activity involving two or more of the cysteines 159, 300, 416, and 418, and (2) by preventing 5-LO/FLAP assemblies involving selectively Cys159 in 5-LO. Interestingly, replacement of Cys159 by serine prevented 5-LO/FLAP assemblies as well, implying Cys159 as determinant for 5-LO/FLAP complex formation at the nuclear membrane required for leukotriene biosynthesis.

Thiazoles and Thiazolidinones as COX/LOX Inhibitors

Inflammation is a natural process that is connected to various conditions and disorders such as arthritis, psoriasis, cancer, infections, asthma, etc. Based on the fact that cyclooxygenase isoenzymes (COX-1, COX-2) are responsible for the production of prostaglandins that play an important role in inflammation, traditional treatment approaches include administration of non-steroidal anti-inflammatory drugs (NSAIDs), which act as selective or non-selective COX inhibitors. Almost all of them present a number of unwanted, often serious, side effects as a consequence of interference with the arachidonic acid cascade. In search for new drugs to avoid side effects, while maintaining high potency over inflammation, scientists turned their interest to the synthesis of dual COX/LOX inhibitors, which could provide numerous therapeutic advantages in terms of anti-inflammatory activity, improved gastric protection and safer cardiovascular profile compared to conventional NSAIDs. Τhiazole and thiazolidinone moieties can be found in numerous biologically active compounds of natural origin, as well as synthetic molecules that possess a wide range of pharmacological activities. This review focuses on the biological activity of several thiazole and thiazolidinone derivatives as COX-1/COX-2 and LOX inhibitors.

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.

Common structural and pharmacophoric features of mPGES-1 and LTC4S

Prostaglandins and leukotrienes are produced in the COX and 5-LOX pathways of the inflammatory process. The current drugs target the upstream enzymes of either of the two pathways, leading to side effects. We have attempted to target the downstream enzymes simultaneously. Two compounds 2 and 3 (10 μM), identified by virtual screening, inhibited mPGES-1 activity by 53.4 ± 4.0 and 53.9 ± 8.1%, respectively. Structural and pharmacophore studies revealed a set of common residues between LTC4S and mPGES-1 as well as four-point pharmacophore mapping onto the inhibitors of both these enzymes as well as 2 and 3. These structural and pharmacophoric features may be exploited for ligand- and structure-based screening of inhibitors and designing of dual inhibitors.

NMR-based identification of the major bioactive molecules from an Italian cultivar of Lycium barbarum

Lycium barbarum (Solanaceae), long known to the traditional Chinese medicine because of its many health-promoting effects, has of late spread widely across the Western hemisphere, mainly on account of the nutritional richness in vitamins, minerals and antioxidant metabolites of its fruits. Data on bioactive metabolites from fruits and leaves, which are commonly consumed in soups and salads, are scarce and sometimes even contradictory. By means of NMR, the present study identified the specialised products contained in an Italian cultivar of L. barbarum. Kaempeferol, caffeic acid, 3,4,5-trihydroxycinnamic acid and 5-hydroxyferulic acid were found in fresh fruits; rutin and chlorogenic acid were detected in leaves and flowers; also, a previously undescribed N,N-dicaffeoylspermidine derivative was identified in flowers, while N-feruloyltyramine derivatives, for which interesting anti-inflammatory properties have been reported, turned out to be the major bioactive molecules in stems. The plethora of the detected bioactive molecules amplifies the nutraceutical value of berries and leaves and prompts the exploitation of L. barbarum flowers and pruned stems as sources of beneficial compounds.

Synergistic Antifungal Effect of Fluconazole Combined with Licofelone against Resistant Candida albicans

Candida albicans (C. albicans) is one of the important opportunistic fungal pathogens that is closely associated with disseminated or chronic infections. The objective of this study is to evaluate the synergistic antifungal effect of licofelone, which is dual microsomal prostaglandin E2 synthase/lipoxygenase (mPGES-1/LOX) inhibitor in combination with fluconazole against C. albicans. Here our results showed that licofelone (16 μg/mL) can synergistically work with fluconazole (1 μg/mL) against planktonic cells of fluconazole-resistant C. albicans. The two-drug combination inhibited the C. albicans biofilm formation over 12 h, and reduced the expression of extracellular phospholipase genes, biofilm-specific genes and RAS/cAMP/PKA pathway related genes. In addition, the two-drug combination inhibited the transition from yeast to hyphal growth form, and decreased the secreted aspartyl proteinase activity, while not affecting the drug efflux pumps activity. Galleria mellonella model was also used to confirm the antifungal activity of the drug combination in vivo. This study first indicates that the combination of fluconazole and licofelone has synergistic effect against resistant C. albicans and could be a promising therapeutic strategy for the antifungal treatment.