Secretory Phospholipase A2 Inhibitor Research Articles

HPLC fluorescence assay for measuring the activity of NAPE-PLD and the action of inhibitors affecting this enzyme

N-Acyl phosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD) is the major enzyme for the biosynthesis of the endocannabinoid anandamide. The role of NAPE-PLD in various physiological and pathophysiological conditions is currently under investigation. For example, the enzyme might be involved in the control of neuronal activity, embryonic development and pregnancy, and prostate cancer. We synthesized a novel NAPE-PLD substrate with a fluorogenic pyrene substituent at the N-acyl residue as tool compound for studying this enzyme. As shown by HPLC with fluorescence detection, in rat brain microsomes the substrate was transformed into the expected pyrene-labeled N-acylethanolamine (NAE), but minor amounts of three by-products could also be detected. In the presence of pan-serine hydrolase and secretory phospholipase A2 inhibitors, the generation of these compounds, whose identity was verified using reference substances, was abolished. Based on these results, a method for determining the activity of NAPE-PLD was developed, validated, and applied to evaluate the action of known inhibitors of this enzyme. With human sperm, it was shown that the fluorescent substrate can also be used to study NAPE metabolism in intact cells.

GPR55 contributes to neutrophil recruitment and mechanical pain induction after spinal cord compression in mice

Pain transmission and processing in the nervous system are modulated by various biologically active substances, including lysophospholipids, through direct and indirect actions on the somatosensory pathway. Lysophosphatidylglucoside (LysoPtdGlc) was recently identified as a structurally unique lysophospholipid that exerts biological actions via the G protein-coupled receptor GPR55. Here, we demonstrated that GPR55-knockout (KO) mice show impaired induction of mechanical pain hypersensitivity in a model of spinal cord compression (SCC) without the same change in the models of peripheral tissue inflammation and peripheral nerve injury. Among these models, only SCC recruited peripheral inflammatory cells (neutrophils, monocytes/macrophages, and CD3+ T-cells) in the spinal dorsal horn (SDH), and GPR55-KO blunted these recruitments. Neutrophils were the first cells recruited to the SDH, and their depletion suppressed the induction of SCC-induced mechanical hypersensitivity and inflammatory responses in compressed SDH. Furthermore, we found that PtdGlc was present in the SDH and that intrathecal administration of an inhibitor of secretory phospholipase A2 (an enzyme required for producing LysoPtdGlc from PtdGlc) reduced neutrophil recruitment to compressed SDH and suppressed pain induction. Finally, by screening compounds from a chemical library, we identified auranofin as a clinically used drug with an inhibitory effect on mouse and human GPR55. Systemically administered auranofin to mice with SCC effectively suppressed spinal neutrophil infiltration and pain hypersensitivity. These results suggest that GPR55 signaling contributes to the induction of inflammatory responses and chronic pain after SCC via the recruitment of neutrophils and may provide a new target for reducing pain induction after spinal cord compression, such as spinal canal stenosis.

The BRAVO Clinical Study Protocol: Oral Varespladib for Inhibition of Secretory Phospholipase A2 in the Treatment of Snakebite Envenoming.

Snakebite is an urgent, unmet global medical need causing significant morbidity and mortality worldwide. Varespladib is a potent inhibitor of venom secretory phospholipase A2 (sPLA2) that can be administered orally via its prodrug, varespladib-methyl. Extensive preclinical data support clinical evaluation of varespladib as a treatment for snakebite envenoming (SBE). The protocol reported here was designed to evaluate varespladib-methyl for SBE from any snake species in multiple geographies. BRAVO (Broad-spectrum Rapid Antidote: Varespladib Oral for snakebite) is a multicenter, randomized, double-blind, placebo-controlled, phase 2 study to evaluate the safety, tolerability, and efficacy of oral varespladib-methyl plus standard of care (SoC) vs. SoC plus placebo in patients presenting with acute SBE by any venomous snake species. Male and female patients 5 years of age and older who meet eligibility criteria will be randomly assigned 1:1 to varespladib-methyl or placebo. The primary outcome is the Snakebite Severity Score (SSS) that has been modified for international use. This composite outcome is based on the sum of the pulmonary, cardiovascular, nervous, hematologic, and renal systems components of the updated SSS. This protocol was submitted to regulatory authorities in India and the US. A Clinical Trial No Objection Certificate from the India Central Drugs Standard Control Organisation, Drug Controller General-India, and a Notice to Proceed from the US Food and Drug Administration have been obtained. The study protocol was approved by properly constituted, valid institutional review boards or ethics committees at each study site. This study is being conducted in compliance with the April 1996 ICH Guidance for Industry GCP E6, the Integrated Addendum to ICH E6 (R2) of November 2016, and the applicable regulations of the country in which the study is conducted. The trial is registered on Clinical trials.gov, NCT#04996264 and Clinical Trials Registry-India, 2021/07/045079 000062.

"Synthesis and Characterization of New Secretory Phospholipase A2-Inhibitor N-P-Substituted-1- ((5-P-Substituted-1, 3, 4-Oxadiazol-2-Yl) Methyl)- 1h-1, 2, 3-Triazole-4-Carboxamides and Their Anti- Inflammatory and Anticancer Activities"

"Synthesis and Characterization of New Secretory Phospholipase A2-Inhibitor N-P-Substituted-1- ((5-P-Substituted-1, 3, 4-Oxadiazol-2-Yl) Methyl)- 1h-1, 2, 3-Triazole-4-Carboxamides and Their Anti- Inflammatory and Anticancer Activities"

Selective C3–H nitration of 2-sulfanilamidopyridines withtert-butyl nitrite

A selective C3–H nitration of bioactive 2-sulfanilamidopyridine derivatives, including corticosteroid 11-β-dehydrogenase isozyme, secretory phospholipase A2inhibitor and human neutrophil elastase inhibitor, has been reported.

Antibody-induced pain-like behavior and bone erosion: links to subclinical inflammation, osteoclast activity, and acid-sensing ion channel 3-dependent sensitization.

Several bone conditions, eg, bone cancer, osteoporosis, and rheumatoid arthritis (RA), are associated with a risk of developing persistent pain. Increased osteoclast activity is often the hallmark of these bony pathologies and not only leads to bone remodeling but is also a source of pronociceptive factors that sensitize the bone-innervating nociceptors. Although historically bone loss in RA has been believed to be a consequence of inflammation, both bone erosion and pain can occur years before the symptom onset. Here, we have addressed the disconnection between inflammation, pain, and bone erosion by using a combination of 2 monoclonal antibodies isolated from B cells of patients with RA. We have found that mice injected with B02/B09 monoclonal antibodies (mAbs) developed a long-lasting mechanical hypersensitivity that was accompanied by bone erosion in the absence of joint edema or synovitis. Intriguingly, we have noted a lack of analgesic effect of naproxen and a moderate elevation of few inflammatory factors in the ankle joints suggesting that B02/B09-induced pain-like behavior does not depend on inflammatory processes. By contrast, we found that inhibiting osteoclast activity and acid-sensing ion channel 3 signaling prevented the development of B02/B09-mediated mechanical hypersensitivity. Moreover, we have identified secretory phospholipase A2 and lysophosphatidylcholine 16:0 as critical components of B02/B09-induced pain-like behavior and shown that treatment with a secretory phospholipase A2 inhibitor reversed B02/B09-induced mechanical hypersensitivity and bone erosion. Taken together, our study suggests a potential link between bone erosion and pain in a state of subclinical inflammation and offers a step forward in understanding the mechanisms of bone pain in diseases such as RA.

Current Anti-Inflammatory Therapies and the Potential of Secretory Phospholipase A2 Inhibitors in the Design of New Anti-Inflammatory Drugs: A Review of 2012 - 2018.

The inflammatory process is a natural self-defense response of the organism to damage agents and its action mechanism involves a series of complex reactions. However, in some cases, this process can become chronic, causing much harm to the body. Therefore, over the years, many anti-inflammatory drugs have been developed aiming to decrease the concentrations of inflammatory mediators in the organism, which is a way of controlling these abnormal chain reactions. The main target of conventional anti-inflammatory drugs is the cyclooxygenase (COX) enzyme, but its use implies several side effects. Thus, based on these limitations, many studies have been performed, aiming to create new drugs, with new action mechanisms. In this sense, the phospholipase A2 (PLA2) enzymes stand out. Among all the existing isoforms, secretory PLA2 is the major target for inhibitor development, since many studies have proven that this enzyme participates in various inflammatory conditions, such as cancer, Alzheimer and arthritis. Finally, for the purpose of developing anti-inflammatory drugs that are sPLA2 inhibitors, many molecules have been designed. Accordingly, this work presents an overview of inflammatory processes and mediators, the current available anti-inflammatory drugs, and it briefly covers the PLA2 enzymes, as well as the diverse structural array of the newest sPLA2 inhibitors as a possible target for the production of new anti-inflammatory drugs.

γ-Hydroxybutenolide Containing Marine Natural Products and Their Synthesis: A Review

:γ-Hydroxybutenolides (γ-HB) is an important structural core found in many bioactive marine natural products (MNPS). The γ-HB core containing NPS served as an inspiration to medicinal chemists to undertake designing of the new synthetic strategies to construct γ-HB core. Subsequently, it further results in the development of novel physiological and therapeutic agents. The most notable example includes manoalides, cacospongionolides, petrosaspongioide M and dysidiolide from marine sponges possessing anti-inflammatory properties. γ-HB containing MNPS were known to possess various pharmacological properties such as antimicrobial (acantholide B), cytotoxic (acantholide A-E, spongianolide A), inhibitors of secretory phospholipase A2 (cladocorans A and B), BACE inhibitors (ianthellidone G), etc. Moreover, the γ-HB moiety was explored as antifouling agents as well. Owing to their numerous biological activities and attractive molecular structures, there are lots of advances in the synthetic methodology of these compounds. This review gives the account on isolation and biological studies of MNPS with γ-HB skeleton as a core unit. Furthermore, the synthesis of selective γ-HB containing bioactive MNPS like manoalide, secomanoalide, cacospongionolides, luffarielloide and dysidiolide were highlighted in the article.

Delayed Oral LY333013 Rescues Mice from Highly Neurotoxic, Lethal Doses of Papuan Taipan (Oxyuranus scutellatus) Venom.

There is an unmet need for economical snakebite therapies with long shelf lives that are effective even with delays in treatment. The orally bioavailable, heat-stable, secretory phospholipase A2 (sPLA2) inhibitor, LY333013, demonstrates antidotal characteristics for severe snakebite envenoming in both field and hospital use. A murine model of lethal envenoming by a Papuan taipan (Oxyuranus scutellatus) demonstrates that LY333013, even with delayed oral administration, improves the chances of survival. Furthermore, LY333013 improves the performance of antivenom even after it no longer reverses neurotoxic signs. Our study is the first demonstration that neurotoxicity from presynaptic venom sPLA2S can be treated successfully, even after the window of therapeutic antivenom has closed. These results suggest that sPLA2 inhibitors have the potential to reduce death and disability and should be considered for the initial and adjunct treatment of snakebite envenoming. The scope and capacity of the sPLA2 inhibitors ability to achieve these endpoints requires further investigation and development efforts.

Developing Small Molecule Therapeutics for the Initial and Adjunctive Treatment of Snakebite.

The World Health Organization (WHO) recently added snakebite envenoming to the priority list of Neglected Tropical Diseases (NTD). It is thought that ~75% of mortality following snakebite occurs outside the hospital setting, making the temporal gap between a bite and antivenom administration a major therapeutic challenge. Small molecule therapeutics (SMTs) have been proposed as potential prereferral treatments for snakebite to help address this gap. Herein, we discuss the characteristics, potential uses, and development of SMTs as potential treatments for snakebite envenomation. We focus on SMTs that are secretory phospholipase A2 (sPLA2) inhibitors with brief exploration of other potential drug targets on venom molecules.

Therapeutic reduction of lysophospholipids in the digestive tract recapitulates the metabolic benefits of bariatric surgery and promotes diabetes remission

ObjectiveObesity and obesity-related metabolic disorders are major health problems worldwide. The most effective obesity intervention is bariatric surgery. This study tested the hypothesis that bariatric surgery alters phospholipid metabolism in the gastrointestinal tract to favor a metabolically healthy gut microbiota profile and therapeutic intervention of phospholipid metabolism in the gastrointestinal may have similar metabolic benefits. MethodsThe first study compared plasma levels of the bioactive lipid metabolites lysophospholipid and trimethylamine N-oxide (TMAO) as well as gut microbiota profile in high fat/carbohydrate (HFHC) diet-fed C57BL/6 mice with or without vertical sleeve gastrectomy (VSG) and in Pla2g1b−/− mice with group 1B phospholipase A2 gene inactivation. The second study examined the effectiveness of the non-absorbable secretory phospholipase A2 inhibitor methyl indoxam to reverse hyperglycemia and hyperlipidemia in HFHC diet-fed C57BL/6 mice after diabetes onset. ResultsBoth bariatric surgery and PLA2G1B inactivation were shown to reduce lysophospholipid content in the gastrointestinal tract, resulting in resistance to HFHC diet-induced alterations of the gut microbiota, reduction of the cardiovascular risk factors hyperlipidemia and TMAO, decreased adiposity, and prevention of HFHC diet-induced diabetes. Importantly, treatment of wild type mice with methyl indoxam after HFHC diet-induced onset of hyperlipidemia and hyperglycemia effectively restored normal plasma lipid and glucose levels and replicated the metabolic benefits of VSG surgery with diabetes remission and TMAO reduction. ConclusionThese results provided pre-clinical evidence that PLA2G1B inhibition in the digestive tract may be a viable alternative option to bariatric surgery for obesity and obesity-related cardiometabolic disorder intervention.

The need for Group IIA secretory phospholipase A2 (sPLA2-IIA) inhibitors in inflammatory ocular disease treatment

The need for Group IIA secretory phospholipase A2 (sPLA2-IIA) inhibitors in inflammatory ocular disease treatment

Novel Dual Inhibitors of Secretory Phospholipase A2 and Sphingomyelin Synthase: Design, Synthesis and Evaluation

Novel Dual Inhibitors of Secretory Phospholipase A2 and Sphingomyelin Synthase: Design, Synthesis and Evaluation

Hepatic Overexpression of Annexin A1 and A2 in Thioacetamide-Primed Mice Protects Them Against Acetaminophen-Induced Liver Failure and Death.

Compensatory tissue repair (CTR) in thioacetamide (TA)-primed rats protects them against acetaminophen (APAP)-induced lethality. This study was aimed at investigating the mechanisms of CTR-mediated heteroprotection in mice. Male Swiss Webster mice received a priming dose of TA (40 mg/kg body weight [BW] in 10 mL distilled water [DW]/kg BW, intraperitoneally [IP]). Thioacetamide-induced liver injury, CTR, and expression of annexin A1 and A2 (ANX1 and ANX2), the endogenous inhibitors of the death protein secretory phospholipase A2 (sPLA2), were measured over a time course of 84 hours after TA priming. Both centrilobular necrosis and CTR peaked at 36 hours after TA priming as indicated by significantly increased plasma alanine transaminase (ALT) and aspartate transaminase (AST) activities, liver histology, and proliferating cell nuclear antigen immunostaining. Thioacetamide priming resulted in the overexpression of ANX1 and ANX2 at 36 to 84 hours and 12 to 60 hours, respectively. A lethal dose of APAP (600 mg/kg BW in 10 mL 0.45% NaCl/kg BW, IP) was given at 12, 24, or 36 hours after TA-priming. Thioacetamide priming did not affect the rise in plasma ALT, AST, sPLA2, and arachidonic acid levels seen at 2 hours after the APAP overdose. Neither these biochemical parameters nor histology suggested any escalation of hepatic injury at later time points (12 and 24 hours after APAP overdose), consistent with 100% survival of the TA + APAP-treated mice compared to DW + APAP-treated mice, which had 100% mortality. Inhibition of ANX1 and ANX2 biosynthesis using cycloheximide (40 mg/kg BW in 5 mL DW/kg BW, IP) abolished this heteroprotection. Our data indicate that hepatic overexpression of ANX1 and ANX2 inhibits APAP-induced expansion of liver injury.

Virtual analysis of structurally diverse synthetic analogs as inhibitors of snake venom secretory phospholipase A2.

Due to the toxic pathophysiological role of snake venom phospholipase A2 (PLA2 ), its compelling limitations to anti-venom therapy in humans and the need for alternative therapy foster considerable pharmacological interest towards search of PLA2 specific inhibitors. In this study, an integrated approach involving homology modeling, molecular dynamics and molecular docking studies on VRV-PL-V (Vipera russellii venom phospholipase A2 fraction-V) belonging to Group II-B secretory PLA2 from Daboia russelli pulchella is carried out in order to study the structure-based inhibitor design. The accuracy of the model was validated using multiple computational approaches. The molecular docking study of this protein was undertaken using different classes of experimentally proven, structurally diverse synthetic inhibitors of secretory PLA2 whose selection is based on IC50 value that ranges from 25 μM to 100 μM. Estimation of protein-ligand contacts by docking analysis sheds light on the importance of His 47 and Asp 48 within the VRV-PL-V binding pocket as key residue for hydrogen bond interaction with ligands. Our virtual analysis revealed that compounds with different scaffold binds to the same active site region. ADME analysis was also further performed to filter and identify the best potential specific inhibitor against VRV-PL-V. Additionally, the e-pharmacophore was generated for the best potential specific inhibitor against VRV-PL-V and reported here. The present study should therefore play a guiding role in the experimental design of VRV-PL-V inhibitors that may provide better therapeutic molecular models for PLA2 recognition and anti-ophidian activity.

Inflammation, oxidative stress and renin angiotensin system in atherosclerosis.

Atherosclerosis is a chronic inflammatory disease associated with cardiovascular dysfunction including myocardial infarction, unstable angina, sudden cardiac death, stroke and peripheral thromboses. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with cardiovascular risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. The impairment of the endothelium associated with cardiovascular risk factors creates an imbalance between vasodilating and vasoconstricting factors, in particular, an increase in angiotensin II (Ang II) and a decrease in nitric oxide. The renin-angiotensin system (RAS), and its primary mediator Ang II, also have a direct influence on the progression of the atherosclerotic process via effects on endothelial function, inflammation, fibrinolytic balance, and plaque stability. Anti-inflammatory agents [statins, secretory phospholipase A2 inhibitor, lipoprotein-associated phospholipase A2 inhibitor, 5-lipoxygenase activating protein, chemokine motif ligand-2, C-C chemokine motif receptor 2 pathway inhibitors, methotrexate, IL-1 pathway inhibitor and RAS inhibitors (angiotensin-converting enzyme inhibitors)], Ang II receptor blockers and ranin inhibitors may slow inflammatory processes and disease progression. Several studies in human using anti-inflammatory agents and RAS inhibitors revealed vascular benefits and reduced progression of coronary atherosclerosis in patients with stable angina pectoris; decreased vascular inflammatory markers, improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis. Recent preclinical studies have demonstrated therapeutic efficacy of vitamin D analogs paricalcitol in ApoE-deficient atherosclerotic mice.

Studies of synthetic chalcone derivatives as potential inhibitors of secretory phospholipase A2, cyclooxygenases, lipoxygenase and pro-inflammatory cytokines.

Arachidonic acid metabolism leads to the generation of key lipid mediators which play a fundamental role during inflammation. The inhibition of enzymes involved in arachidonic acid metabolism has been considered as a synergistic anti-inflammatory effect with enhanced spectrum of activity. A series of 1,3-diphenyl-2-propen-1-one derivatives were investigated for anti-inflammatory related activities involving inhibition of secretory phospholipase A2, cyclooxygenases, soybean lipoxygenase, and lipopolysaccharides-induced secretion of interleukin-6 and tumor necrosis factor-alpha in mouse RAW264.7 macrophages. The results from the above mentioned assays exhibited that the synthesized compounds were effective inhibitors of pro-inflammatory enzymes and cytokines. The results also revealed that the chalcone derivatives with 4-methlyamino ethanol substitution seem to be significant for inhibition of enzymes and cytokines. Molecular docking experiments were carried out to elucidate the molecular aspects of the observed inhibitory activities of the investigated compounds. Present findings increase the possibility that these chalcone derivatives might serve as a beneficial starting point for the design and development of improved anti-inflammatory agents.

Discovery of Novel Secretory Phospholipase A2 Inhibitors Using Virtual Screen

Human non-pancreatic secretory phospholipase A2 was reported to be associated with inflammatory diseases and considered as a potential drug target for inflammation and other related disease treatment. Although many human non-pancreatic secretory phospholipase A2 inhibitors were reported, few entered into the drug development stage due to various problems. In this study, we discovered seven novel human non-pancreatic secretory phospholipase A2 inhibitors using virtual screen. Of the 99 compounds tested by continuous fluorescence assay, seven are potent human non-pancreatic secretory phospholipase A2 inhibitors with micromolar IC50 values. Typical molecules include 9-fluorenylmethoxycarbonyl protected α-phenylalanine derivatives and azo compounds, which may serve as novel scaffold for developing potent human non-pancreatic secretory phospholipase A2 inhibitors. These compounds bind to human non-pancreatic secretory phospholipase A2 by interacting with the catalytic calcium ion and the hydrophobic regions in the substrate-binding pocket.

Pharmacological evaluation and docking studies of α,β-unsaturated carbonyl based synthetic compounds as inhibitors of secretory phospholipase A2, cyclooxygenases, lipoxygenase and proinflammatory cytokines

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

Targeting inflammation—what has the VISTA-16 trial taught us?

The VISTA-16 trial of varespladib, a secretory phospholipase A2 (sPLA2) inhibitor, in patients with an acute coronary syndrome was terminated prematurely owing to futility and a signal towards harm. Despite these discouraging results, therapies that target inflammation to modify pathways in atherogenesis remain an area of active investigation.