Natural inhibitors against potential targets of cyclooxygenase, lipoxygenase and leukotrienes

Background: The cyclooxygenase (COX) and lipoxygenase (LOX) enzymes catalyze the production of pain mediators like prostaglandins (PGs) and leukotrienes (LTs) respectively from arachidonic acid. Introduction: The COX and LOX enzyme modulators are responsible for the major PGs and LTs mediated complications like asthma, osteoarthritis, rheumatoid arthritis, cancer, Alzheimer’s disease, neuropathy and cardiovascular syndromes (CVS). Many synthetic nonsteroidal anti-inflammatory drugs (NSAIDs) used in the treatment have serious side effects like nausea, vomiting, hyperacidity, gastrointestinal ulcers, CVS, etc. Methods: The natural inhibitors of pain mediators have great acceptance worldwide due to fewer side effects on long-term uses. The present review is an extensive study of the advantages of plant-based vs synthetic inhibitors. Results: These natural COX and LOX inhibitors control inflammatory response without causing side-effect-related complicacy. Conclusion: Therefore, the natural COX and LOX inhibitors may be used as alternative medicines for the management of pain and inflammation due to their less toxicity and resistivity.

Docking Studies and Molecular Dynamics Simulation of Compounds Contained in Kaempferia Galanga L. to Lipoxygenase (LOX) for Anti-Inflammatory Drugs

Inflammation is a self-protective response to start the healing process. An anti-inflammatory target worth developing are lipoxygenase inhibitors, which have been studied for several diseases, including severe respiratory disease. This research had the goals of estimating the activity of 21 compounds from K. galanga to inhibit the lipoxygenase (LOX) and estimating the bond stability of the ligand-LOX complex. Based on the compound’s affinity for LOX, the compounds in K. galanga were selected by utilizing the PLANTS docking software, with zileuton as the reference ligand. The GROMACS application was used to simulate the molecular dynamics of the LOX-ligand complex at 310 K. Based on the chemPLP score, most of the 21 K. galanga compounds showed a higher affinity towards 5-LOX compared to zileuton. δ-3-carene had the best affinity for 5-LOX. In the simulation of molecular dynamics until 20 ns, the RMSD of δ-3-carene and 5-LOX was not more than 0.03 nm or 0.3 Å, indicating that the whole system showed decent stability and had ‑1.67392 x 106 kcal/mol as the average potential energy. The results showed that K. galanga contains active components of 5-LOX inhibitors that could be developed.

Changes of L-Arginine Metabolism in Rat`S Colon Mucosa Under the Conditions of COX/LOX Inhibition and Acute Stress Action

Introduction. L-arginine is a semi-essential amino acid and a precursor of many biologically active compounds. Polyamines and NO produced from L-arginine take part in the regulation of biochemical processes in colon mucosa. Emotional stress, nonsteroidal anti-inflammatory drugs (NSAIDs) and their combined action can change the activity of L-arginine metabolizing enzymes. The aim of this study was to investigate the single action of NSAIDs with different mechanisms of action and their combination with acute stress on L-arginine metabolism in colon mucosa of rats. Methods. Animals were divided into 8 groups: control group (1), administration of nonselective, COX-2 selective and dual COX-2/5-LOX inhibitors (groups 2-4), acute stress group (5), administration of same NSAIDs as in groups 2-4 under the conditions of acute stress (groups 6-8). The activity of iNOS, cNOS, arginase, concentration of L-arginine, nitrite and nitrate was measured in colon mucosa. Results. Nonselective COX inhibition by naproxen caused the increase in iNOS and decrease in cNOS activity in colon mucosa. Both COX-2 (celecoxib) and dual COX-2/5-LOX (2A5DHT) inhibitors enhanced cNOS and arginase acting in combination with acute stress. The concentration of L-arginine remained unchanged in most of the groups, but combination of dual COX-2/5-LOX inhibitor and acute stress raised this parameter.

Design of Dual COX-2 and 5-LOX Inhibitors with Iron-Chelating Properties Using Structure-Based and Ligand-Based Methods

Background: Inflammation is common pathogenesis of many diseases progression, such as malignancy, cardiovascular and rheumatic diseases. The inhibition of the synthesis of inflammatory mediators by modulation of cyclooxygenase (COX) and lipoxygenase (LOX) pathways provides a challenging strategy for the development of more effective drugs. Objective: The aim of this study was to design dual COX-2 and 5-LOX inhibitors with iron-chelating properties using a combination of ligand-based (three-dimensional quantitative structure-activity relationship (3D-QSAR)) and structure-based (molecular docking) methods. Methods: The 3D-QSAR analysis was applied on a literature dataset consisting of 28 dual COX-2 and 5-LOX inhibitors in Pentacle software. The quality of developed COX-2 and 5-LOX 3D-QSAR models were evaluated by internal and external validation methods. The molecular docking analysis was performed in GOLD software, while selected ADMET properties were predicted in ADMET predictor software. Results: According to the molecular docking studies, the class of sulfohydroxamic acid analogues, previously designed by 3D-QSAR, was clustered as potential dual COX-2 and 5-LOX inhibitors with iron-chelating properties. Based on the 3D-QSAR and molecular docking, 1j, 1g, and 1l were selected as the most promising dual COX-2 and 5-LOX inhibitors. According to the in silico ADMET predictions, all compounds had an ADMET_Risk score less than 7 and a CYP_Risk score lower than 2.5. Designed compounds were not estimated as hERG inhibitors, and 1j had improved intrinsic solubility (8.704) in comparison to the dataset compounds (0.411-7.946). Conclusion: By combining 3D-QSAR and molecular docking, three compounds (1j, 1g, and 1l) are selected as the most promising designed dual COX-2 and 5-LOX inhibitors, for which good activity, as well as favourable ADMET properties and toxicity, are expected.

In Vitro Effects of Selective COX and LOX Inhibitors and Their Combinations with Antineoplastic Drugs in the Mouse Melanoma Cell Line B16F10

The constitutive expression or overactivation of cyclooxygenase (COX) and lipoxygenase (LOX) enzymes results in aberrant metabolism of arachidonic acid and poor prognosis in melanoma. Our aim is to compare the in vitro effects of selective COX-1 (acetylsalicylic acid), COX-2 (meloxicam), 5-LOX (MK-886 and AA-861), 12-LOX (baicalein) and 15-LOX (PD-146176) inhibition in terms of proliferation (SRB assay), mitochondrial viability (MTT assay), caspase 3-7 activity (chemiluminescent assay), 2D antimigratory (scratch assay) and synthesis of eicosanoids (EIA) in the B16F10 cell line (single treatments). We also explore their combinatorial pharmacological space with dacarbazine and temozolomide (median effect method). Overall, our results with single treatments show a superior cytotoxic efficacy of selective LOX inhibitors over selective COX inhibitors against B16F10 cells. PD-146176 caused the strongest antiproliferation effect which was accompanied by cell cycle arrest in G1 phase and an >50-fold increase in caspases 3/7 activity. When the selected inhibitors are combined with the antineoplastic drugs, only meloxicam provides clear synergy, with LOX inhibitors mostly antagonizing. These apparent contradictions between single and combination treatments, together with some paradoxical effects observed in the biosynthesis of eicosanoids after FLAP inhibition in short term incubations, warrant further mechanistical in vitro and in vivo scrutiny.

Some Dietary Phenolic Compounds Can Activate Thyroid Peroxidase and Inhibit Lipoxygenase-Preliminary Study in the Model Systems

The presented research concerns the triple activity of trans-cinnamic (tCA), ferulic (FA) and syringic acids (SA). They act as thyroid peroxidase (TPO) activators, lipoxygenase (LOX) inhibitors and show antiradical activity. All compounds showed a dose-dependent TPO activatory effect, thus the AC50 value (the concentration resulting in 50% activation) was determined. The tested compounds can be ranked as follows: tCA > FA > SA with AC50 = 0.10, 0.39, 0.69 mM, respectively. Strong synergism was found between FA and SA. The activatory effects of all tested compounds may result from interaction with the TPO allosteric site. It was proposed that conformational change resulting from activator binding to TPO allosteric pocket results from the flexibility of a nearby loop formed by residues Val352-Tyr363. All compounds act as uncompetitive LOX inhibitors. The most effective were tCA and SA, whereas the weakest was FA (IC50 = 0.009 mM and IC50 0.027 mM, respectively). In all cases, an interaction between the inhibitors carboxylic groups and side-chain atoms of Arg102 and Arg139 in an allosteric pocket of LOX was suggested. FA/tCA and FA/SA acted synergistically, whereas tCA/SA demonstrated antagonism. The highest antiradical activity was found in the case of SA (IC50 = 0.22 mM). FA/tCA and tCA/SA acted synergistically, whereas antagonism was found for the SA/FA mixture.

Identification of a Prenyl Chalcone as a Competitive Lipoxygenase Inhibitor: Screening, Biochemical Evaluation and Molecular Modeling Studies

Cyclooxygenase (COX) and lipoxygenase (LOX) are key targets for the development of new anti-inflammatory agents. LOX, which is involved in the biosynthesis of mediators in inflammation and allergic reactions, was selected for a biochemical screening campaign to identify LOX inhibitors by employing the main natural product library of Brazilian biodiversity. Two prenyl chalcones were identified as potent inhibitors of LOX-1 in the screening. The most active compound, (E)-2-O-farnesyl chalcone, decreased the rate of oxygen consumption to an extent similar to that of the positive control, nordihydroguaiaretic acid. Additionally, studies on the mechanism of the action indicated that (E)-2-O-farnesyl chalcone is a competitive LOX-1 inhibitor. Molecular modeling studies indicated the importance of the prenyl moieties for the binding of the inhibitors to the LOX binding site, which is related to their pharmacological properties.

New 5-LOX and 15-LOX Inhibitors Isolated from Red Sea Derived Brown Alga Sarragassum Cinnerum: An In Silico-Supported Study

Sargassum is a brown algal genus inhabiting tropical region. Metabolomic profiling of Sarragassum cinnerum “Sargassaceae”, dereplicated eleven compounds 1-11, further phytochemical investigation afforded two new aryl cresol 12-13, along with eight known compounds 14-21. Both new metabolites along with 19 showed moderate in vitro antiproliferative activity against HEPG2, MCF7, and CACO2. Molecular targets of the bioactive compounds using a pharmacophore-based virtual screening, predicts 5-LOX and 15-LOX as the most probable target linked to their observed antiproliferative activity. The validation step revealed 12 and 13 inhibited 5-LOX more prudentially than 15-LOX, while 19 showed a convergent inhibitory activity toward both enzymes. Further in-depth in silico analysis revealed the molecular interactions inside both enzymes active sites and explained the varying inhibitory activity for 12, and 13 toward 5-LOX and 15-LOX. Taken together, unique metabolites in S. cinnerum had potential anticancer activity supported with in-silico investigations to facility drug discovery and development processes.

Lipoxygenase (LOX) Pathway: A Promising Target to Combat Cancer

: Leukotrienes are one of the major eicosanoid lipid mediators being produced as a result of oxidative transformation of arachidonic acid. Subsequently, they get converted into various cellular signaling hormones by a series of enzymes of myeloid origin to mediateor debilitate inflammation. Interestingly, the available literature demonstrates the pivotal role of eicosanoids in neurodegenerative, obesity, diabetes, cardiovascular diseases and cancers as well. The aberrant metabolism of arachidonic acid by LOX pathway is a common feature of epithelial derived malignancies and suggests the contributory role of dietary fats in carcinogenesis. The enzymes and receptors of the LOX pathway play a significant role in cell proliferation, differentiation and regulation of apoptosis through multiple signaling pathways and have been reported to be involved in various cancers including prostate, colon, lung and pancreatic cancers. So far, leukotriene receptor antagonists and 5-LOX inhibitors have reached up to the clinical trials for treating various diseases. Keeping its various roles in cancer, the review highlights the components of the leukotriene synthesizing machinery, emerging opportunities for pharmacological intervention, and the probability of considering lipoxygenases and leukotriene receptors as good candidates for clinical chemoprevention studies.