Inhibited Leukotriene B4 Research Articles

A novel core skeleton design and synthesis of N‐alkyl‐1′‐(substituted sulfonyl)spiro[chromene‐2,4′‐piperidin]‐6‐amine derivatives as 5‐lipoxygenase inhibitors

Abstract5‐LO inhibitors can potentially be employed for the treatment of various inflammatory disorders. In this study, we have designed and synthesized new N‐alkyl‐1′‐(substituted sulfonyl)spiro[chromene‐2,4′‐piperidin]‐6‐amine‐based library as potential and novel 5‐LO inhibitors. In vitro results showed that several synthesized compounds exhibited high 5‐LO inhibitory activity, in parallel with the inhibition of leukotriene B4 (LTB4) production in the rat basophilic leukemia (RBL‐1) cells. Among the synthesized compounds, 8l was selected for in vivo study using a mouse ear edema model: oral administration of 8l (100 mg/kg) inhibited arachidonic acid‐induced ear edema, myeloperoxidase (MPO) activity, and LTB4 synthesis. SAR analysis and molecular docking studies demonstrated the allosteric binding mode between 5‐LO and the synthesized compounds including 8l.

LTB4 Promotes Acute Lung Injury via Upregulating the PLCε-1/TLR4/NF-κB Pathway in One-Lung Ventilation.

Background Mechanical ventilation (MV) can provoke acute lung injury (ALI) by increasing inflammation activation and disrupting the barrier in lung tissues even causing death. However, the inflammation-related molecules and pathways in MV-induced ALI remain largely unknown. Hence, the purposes of this study are to examine the role and mechanism of a novel inflammation-related molecule, leukotriene B4 (LTB4), in ALI. Methods The functions of LTB4 in one-lung ventilation (OLV) model were detected by the loss-of-function experiments. H&E staining was used to examine the pathologic changes of lung tissues. Functionally, PLCε-1 knockdown and Toll-like receptor 4 (TLR4)/NF-κB pathway inhibitor were used to detect the regulatory effects of LTB4 on the phospholipase Cε (PLCε-1)/TLR4/nuclear factor-kappa B (NF-κB) pathway. The levels of genes and proteins were determined by RT-qPCR and western blotting assay. The levels of inflammation cytokines and chemokines were measured by ELISA. Results Here, we found LTA4H, leukotriene B (4) receptor 1 (BLT1), LTB4, and PLCε-1 upregulated in OLV rats and associated with inflammatory activation and lung permeability changes of lung tissues. Inhibition of LTB4 alleviated the OLV-induced ALI by inhibiting inflammatory activation and lung permeability changes of lung tissues. For mechanism analyses, LTB4 promoted OLV-induced ALI by activating the PLCε-1/TLR4/NF-κB pathway. Conclusion LTB4 induced ALI in OLV rats by activating the PLCε-1/TLR4/NF-κB pathway. Our findings might supply a new potential therapeutic for OLV-induced ALI.

Synthesis, Characterization and Biological Evaluation of Chalcones and Its Derivatives for Antibacterial and Anti Inflammatory Activity

Chemistry or Medicinal chemistry is a discipline at the Interchange ofchemistry and pharmacology engaged with designing, methodize andcreating drug chalcones is a conventional term given tointensifies bearing the (E)- 1,3-diphenylprop-2-en-1-one, which can befunctionlized in the propane chain by the presence of olefinic, keto as well ashydroxyl group.Chalcones are a significant class of regular items and are considered as the forerunners of flavonoids and isoflavonoids. Synthetically, is (E)-1,3-diphenylprop-2-en-1-one in which two aromatic ring rings are joined by a three carbon bond having a carbonyl moiety and and α, β unsaturation. The compounds with the backbone of chalcones have been accounted for to have different pharmacological activities for example, antimicrobial, anti- inflammatory, analgesic, anti-platelet, anti-ulcerative, antimalarial, anticancer, antiviral, anti-leishmanial, antioxidant, antitubercular, anti-hyperglycemic, immunomodulatory, inhibition of chemical mediators release, inhibition of leukotriene B4, inhibition of tyrosinase and inhibition of aldose reductase activities. This paper mainly focuses on chalcones synthesized by Claisen Schmidt condensation which involves the condensation between an aromatic aldehyde or ketone with an aliphatic ketone or aldehyde catalysed by the presence of dilute alkali or acid to form alpha beta unsaturated compound. through reviewing different biological significance of chalcones andtheir derivatives have been reported along with their antibacterial movement against, Bacillus pumilis, Bacillus subtilis (gram-positive) and Escherichia coli, Proteus vulgaris (gram-negative). The antiinflammatory action of the sixteen chalcones has been assessed byutilizing carrageenan-actuated rodent paw oedema strategy.

Dapsone Suppresses Disease in Preclinical Murine Models of Pemphigoid Diseases

Epidermolysis bullosa acquisita and mucous membrane pemphigoid are autoimmune blistering diseases characterized by mucocutaneous blisters elicited by an autoantibody-mediated immune response against specific proteins of the epidermal basement membrane. The antibiotic dapsone is frequently used to treat both diseases, but its therapeutic effectiveness is uncertain, and its mode of action in these diseases is largely unknown. We evaluated the effect of dapsone in antibody transfer mouse models of epidermolysis bullosa acquisita and mucous membrane pemphigoid, which do not allow the drawing of conclusions on clinical treatment regimens but can be instrumental to partially uncover the mode(s) of action of dapsone in these diseases. Dapsone significantly mitigated inflammation in both models, reducing the recruitment of neutrophils into the skin and disrupting their release of leukotriene B4 (LTB4) and ROS in response to immune complexes. LTB4 has been implicated in numerous diseases, but effective LTB4 inhibitors for clinical use are not available. Our findings indicate that the mode of action of dapsone in these models may be based on the inhibition of LTB4 and ROS release from neutrophils. Moreover, they encourage testing the use of dapsone as an effective, albeit nonspecific, inhibitor of LTB4 biosynthesis in other LTB4-driven diseases.

Molecular pathways involved in lymphedema: Hydroxytyrosol as a candidate natural compound for treating the effects of lymph accumulation

Lymphedema is a chronic accumulation of interstitial fluid due to inefficient lymph drainage. Major causes of lymphedema are malformations of lymphatic vessels, trauma, toxic damage and surgery. The swelling typically affects the limbs. Lymphedema may be primary, caused by genetic mutations and relatively rare, or secondary (acquired), due to external causes such as infections or surgery. Fluid accumulation induces pathological changes: activation of the inflammatory cascade, immune cell infiltration, tissue fibrosis, adipose accumulation. We focused on the inflammatory phenotype mediated by leukotriene B4, a lipid mediator of the inflammatory pathway, and the potential therapeutic effect of hydroxytyrosol.We conducted an electronic search in PubMed using “lymphedema”, “lymphedema pathway”, “hydroxytyrosol” as keywords. We found that lymphedema deregulates at least six molecular pathways and that hydroxytyrosol, a compound with antioxidant activity, can improve endothelial dysfunction, hemostatic and lipid profiles, and decrease oxidative stress and inflammation through inhibition of leukotriene B4 activity.This review is the first to highlight the possibility of using hydroxytyrosol to treat the secondary effects of lymphedema, especially inflammation. The possible effects of hydroxytyrosol on lymphedema should be tested in vitro and in vivo to find the best way to treat patients with lymphedema in order to improve their health status.

Leukotriene B4 Contributes to Development of Cardiac Allograft Vasculopathy

Purpose Cardiac allograft vasculopathy (CAV) is a highly prevalent vaso-occlusive disease that is a leading cause of graft failure and mortality after heart transplantation. While the pathogenesis of CAV remains incompletely understood, histologic evidence suggests that macrophages, which constitute an important part of the innate immune response, may play an important role. Prior studies in pulmonary hypertension have shown that macrophage-derived leukotriene B4 (LTB4) induces proliferation and hypertrophy of human pulmonary artery smooth muscle cells. We hypothesized that LTB4 plays a similar role in the development of CAV. Methods Human studies: We performed immunofluorescence staining of sections from human CAV+ and CAV- coronary arteries with CD68 (macrophage marker) and 5-LO (5-lipoxygenase, LTB4-producing enzyme), and measured serial LTB4 plasma levels in 14 patients with angiographic CAV and 14 matched CAV- controls. Rat model: We performed aortic transplants in a rat CAV model (Fischer into Lewis orthotopic aortic transplants, n=11) with allogeneic transplants as controls (n=6), and performed CD68 and 5-LO staining of aortic cross-sections of mice with and without aortic intimal hyperplasia. We then treated rat allogeneic transplants with bestatin (protease inhibitor that blocks LTB4 production) to determine whether LTB4 inhibition can prevent the intimal proliferation seen in this rat CAV model. Results Immunofluorescence staining showed that 5-LO co-localized with CD68+ macrophages in the intimal layer of CAV+ human arterioles and in allogeneic rat aortic transplant models. Plasma LTB4 levels were higher in CAV+ cases compared to CAV- controls (n=14 per group, p Conclusion Macrophage-derived leukotriene B4 may contribute to development of CAV. Blockade of LTB4 synthesis has the potential to prevent CAV development after heart transplantation.

Inhibition of 5-lipoxygenase alleviates graft-versus-host disease.

Leukotriene B4 (LTB4), a proinflammatory mediator produced by the enzyme 5-lipoxygenase (5-LO), is associated with the development of many inflammatory diseases. In this study, we evaluated the participation of the 5-LO/LTB4 axis in graft-versus-host disease (GVHD) pathogenesis by transplanting 5-LO-deficient leukocytes and investigated the effect of pharmacologic 5-LO inhibition by zileuton and LTB4 inhibition by CP-105,696. Mice that received allogeneic transplant showed an increase in nuclear 5-LO expression in splenocytes, indicating enzyme activation after GVHD. Mice receiving 5-LO-deficient cell transplant or zileuton treatment had prolonged survival, reduced GVHD clinical scores, reduced intestinal and liver injury, and decreased levels of serum and hepatic LTB4 These results were associated with inhibition of leukocyte recruitment and decreased production of cytokines and chemokines. Treatment with CP-105,696 achieved similar effects. The chimerism or the beneficial graft-versus-leukemia response remained unaffected. Our data provide evidence that the 5-LO/LTB4 axis orchestrates GVHD development and suggest it could be a target for the development of novel therapeutic strategies for GVHD treatment.

Let-7 microRNA-dependent control of leukotriene signaling regulates the transition of hematopoietic niche in mice

Hematopoietic stem and progenitor cells arise from the vascular endothelium of the dorsal aorta and subsequently switch niche to the fetal liver through unknown mechanisms. Here we report that vascular endothelium-specific deletion of mouse Drosha (DroshacKO), an enzyme essential for microRNA biogenesis, leads to anemia and death. A similar number of hematopoietic stem and progenitor cells emerge from Drosha-deficient and control vascular endothelium, but DroshacKO-derived hematopoietic stem and progenitor cells accumulate in the dorsal aorta and fail to colonize the fetal liver. Depletion of the let-7 family of microRNAs is a primary cause of this defect, as it leads to activation of leukotriene B4 signaling and induction of the α4β1 integrin cell adhesion complex in hematopoietic stem and progenitor cells. Inhibition of leukotriene B4 or integrin rescues maturation and migration of DroshacKO hematopoietic stem and progenitor cells to the fetal liver, while it hampers hematopoiesis in wild-type animals. Our study uncovers a previously undefined role of innate leukotriene B4 signaling as a gatekeeper of the hematopoietic niche transition.

Neutrophils in cisplatin AKI—mediator or marker?

Inflammation is an important mediator of most forms of acute kidney injury (AKI). Although neutrophils are prominent components of theinflammatory cascade, the precise role of neutrophils in AKI and the mechanisms by which they contribute to AKI remain controversial. In this issue, Deng etal. identify an important cross talk between renal epithelial cells and neutrophils involving the production and action ofleukotriene B4 in mediating cisplatin AKI. We discuss the possible explanations for the discrepant findings that have been reported for neutrophils in cisplatin AKI.

The Endocannabinoid Metabolite Prostaglandin E2 (PGE2)-Glycerol Inhibits Human Neutrophil Functions: Involvement of Its Hydrolysis into PGE2 and EP Receptors.

The endocannabinoids 2-arachidonoyl-glycerol and N-arachidonoyl-ethanolamine mediate an array of pro- and anti-inflammatory effects. These effects are related, in part, to their metabolism by eicosanoid biosynthetic enzymes. For example, N-arachidonoyl-ethanolamine and 2-arachidonoyl-glycerol can be metabolized by cyclooxygenase-2 into PG-ethanolamide (PG-EA) and PG-glycerol (PG-G), respectively. Although PGE2 is a recognized suppressor of neutrophil functions, the impact of cyclooxygenase-derived endocannabinoids such as PGE2-EA or PGE2-G on neutrophils is unknown. This study's aim was to define the effects of these mediators on neutrophil functions and the underlying cellular mechanisms involved. We show that PGE2-G, but not PGE2-EA, inhibits leukotriene B4 biosynthesis, superoxide production, migration, and antimicrobial peptide release. The effects of PGE2-G were prevented by EP1/EP2 receptor antagonist AH-6809 but not the EP4 antagonist ONO-AE2-227. The effects of PGE2-G required its hydrolysis into PGE2, were not observed with the non-hydrolyzable PGE2-serinol amide, and were completely prevented by methyl-arachidonoyl-fluorophosphate and palmostatin B, and partially prevented by JZL184 and WWL113. Although we could detect six of the documented PG-G hydrolases in neutrophils by quantitative PCR, only ABHD12 and ABHD16A were detected by immunoblot. Our pharmacological data, combined with our protein expression data, did not allow us to pinpoint one PGE2-G lipase, and rather support the involvement of an uncharacterized lipase and/or of multiple hydrolases. In conclusion, we show that PGE2-G inhibits human neutrophil functions through its hydrolysis into PGE2, and by activating the EP2 receptor. This also indicates that neutrophils could regulate inflammation by altering the balance between PG-G and PG levels in vivo.

Hybrid Receptor-Bound/MM-GBSA-Per-residue Energy-Based Pharmacophore Modelling: Enhanced Approach for Identification of Selective LTA4H Inhibitors as Potential Anti-inflammatory Drugs.

Leukotriene A4 hydrolase has been identified as an enzyme with dual anti- and pro-inflammatory role, thus, the conversion of leukotriene to leukotriene B4 in the initiation stage of inflammation and the removal of the chemotactic Pro-Gly-Pro tripeptide. These findings make leukotriene A4 hydrolase an attractive drug target: suggesting an innovative approach towards the identification and design of novel class of compounds that can selectively inhibit leukotriene B4 synthesis while sparing the aminopeptidase activity. Previous inhibitors block the dual activity of the enzyme. Recently, a small lead molecule inhibitor denoted as ARM1 has been identified to block the hydrolase activity of leukotriene A4 hydrolase whilst sparing the aminopeptidase activity. In this study, a hybrid receptor-bound/MM-GBSA-per-residue energy based pharmacophore modeling approach was implemented to identify potential selective hydrolase inhibitors of leukotriene A4 hydrolase. In this approach, active site residues that favorably contributed to the binding of the bound conformation of ARM1 were derived from MD ensembles and MM/GBSA thermodynamic calculations. These residues were then mapped to key pharmacophore features of ARM1. The generated pharmacophore model was used to search the ZINC database for 3D structures that match the pharmacophore. Five new compounds have been identified and proposed as potential epoxide hydrolase selective inhibitors of leukotriene A4 hydrolase. Molecular docking and MM/GBSA analyses revealed that, these top five lead-like compounds ZINC00142747, ZINC94260794, ZINC01382396, ZINC02508448, and ZINC53994447 showed better binding affinities to the hydrolase active site pocket compared to ARM1. Per-residue energy decomposition analysis revealed that amino acid residues Phe314, Tyr378, Pro382, Trp311, Val367, and Ala377 are key residues critical in the selective inhibition of these hits. Information highlighted in this study may guide the the design the next generation of novel and potent epoxide hydrolase selective inhibitors of leukotriene A4 hydrolase.

Synthesis and Medicinal Significance of Chalcones- A Review

Chalcone is an aromatic ketone that forms a central core for a variety of important biological compounds, which are collectively known as chalcones. They possess different activities like antibacterial, antifungal, anti-inflammatory and anti tumor etc depending on the substitution made on them. Chalcones are 1,3-diphenyl-2-propene-1-one, in which two aromatic rings are linked by a three carbon α, β-unsaturated carbonyl system.These are abundant in edible plants and are considered to be precursors of flavonoids and isoflavonoids. Chalcones possess conjugated double bonds and a completely delocalized Π-electron system on both benzene rings. Molecules possessing such system have relatively low redox potentials and have a greater probability of undergoing electron transfer reactions. The compounds with the backbone of chalcones have been reported to possess various biological activities such as antimicrobial, anti-inflammatory, analgesic, anti platelet, anti ulcerative, anti malarial, anticancer, antiviral, anti leishmanial, antioxidant, anti tubercular, anti hyperglycemic, immunomodulatory, inhibition of chemical mediators release, inhibition of leukotriene B4, inhibition of tyrosinase and inhibition of aldose reductase activities. The presence of a reactive alpha, beta -unsatutated keto function in chalcones is found to be responsible for their antimicrobial activity. In this paper through reviewing different biological significance of chalcones and their derivatives have been reported along with their chemistry and of synthesis. Synthetically or chemically chalcones are synthesized by two reactions: a) Aldol condensation and b) Claisen Schmidt condensation. But here is a focus on chalcones synthesized by Claisen Schmidt condensation which involves the condensation between an aromatic aldehyde or ketone with an aliphatic ketone or aldehyde catalysed by the presence of dilute alkali or acid to form alpha beta unsaturated compound.

Relative Inhibitions of 5-Lipoxygenase and Myeloperoxidase and Free-Radical Scavenging Activities of Daidzein, Dihydrodaidzein, and Equol.

The effects of bioavailability and metabolic transformation on the biological activities of daidzein are relatively unknown. The effects of daidzein, dihydrodaidzein, and equol at physiologically relevant concentrations on the production of leukotriene B4 and F2-isoprostanes, and myeloperoxidase enzyme activity in freshly isolated human neutrophils were examined. Equol, at physiological concentrations, inhibited leukotriene B4 production (IC50-200 nmol/L) in human neutrophils significantly more than daidzein and dihydrodaidzein (IC50 values >1000 nmol/L). Daidzein, dihydrodaidzein, and equol did not affect the enzymatic hydrolysis of leukotriene A4 to leukotriene B4, suggesting that they exerted their inhibitory effects on the 5-lipoxygenase activity. Daidzein (IC50 = 600 nmol/L) protected against free radical peroxidation of arachidonic acid significantly more than did equol and dihydrodaidzein (IC50 values >1000 nmol/L). Equol also showed significantly greater inhibition of myeloperoxidase activity (IC50 = 450 nmol/L) when compared to daidzein and dihydrodaidzein. Equol accumulated within the human neutrophils at significantly higher concentrations than daidzein and dihydrodaidzein after incubation with the three compounds at physiologically relevant concentrations. Neutrophils were able to accumulate intracellular daidzein, dihydrodaidzein, and equol up to a concentration of ∼600 nmol/L. Our results provide in vitro evidence that the biological activities of daidzein are profoundly influenced by bioavailability and metabolic transformation.

Miconidin Acetate and Primin as Potent 5-Lipoxygenase Inhibitors from Brazilian Eugenia hiemalis (Myrtaceae)

This paper describes the isolation and identification of primin and miconidin acetate as metabolites from the flower bud extract of Eugenia hiemalis as well as the anti-inflammatory activity of miconidin acetate by inhibition of 5-lipoxygenase. Miconidin acetate inhibited leukotriene B4 formation catalyzed by the human recombinant enzyme (IC50 = 0.3 ± 0.17 µM) more than primin (IC50 = 1.4 ± 0.6 µM) and zileuton (IC50 = 1.1 ± 0.7 µM). Miconidin acetate (20 µM) inhibited LTB4 formation to an extent of 59 ± 12 % in vitro using a cell-based assay, comparable to the positive control zileuton (69 ± 12 % inhibition at a concentration of 10 µM). The binding modes of miconidin acetate were further evaluated in silico by molecular docking to the human 5-lipoxygenase crystal structure. The hydroxyl group was predicted to form a hydrogen bond with the terminal Ile676, while the pentyl moiety occupied the hydrophobic substrate channel. The obtained results show that flower buds of E. hiemalis are an interesting source of anti-inflammatory compounds, mainly of miconidin acetate.

Maximum Time of the Effect of Antileukotriene - Zileuton in Treatment of Patients with Bronchial Asthma.

Objective:Maximum time of the effect of antileukotriene substances - Zileuton in the treatment of patients with bronchial asthma and increased bronchial reactivity and of the salbutamol as agonist of the beta2 adrenergic receptor studied in this work.Methods:Parameters of the lung function are determined with Body plethysmography. Raw and ITGV were registered and specific resistance (SRaw) was calculated. Zileuton (Zyflo, tbl. 600 mg), producer Cornerstone Therapeutics, USA was used in the research.Results:Results of this research, in patients with bronchial asthma, indicate that antileukotriene substances–Zileuton administered in a dose of 600 mg first day (oral route of administration 4 × 1 tbl.) has not caused significant decrease of the specific resistance of the airways (SRaw) (p value 0.1 > Alpha 0.05), whereas Zileuton administered two days in a row, in a dose of 600 mg (4 × 1 tbl. a day), has caused significant decrease of the specific resistance of the airways (SRaw) (P value 0.03 < Alpha 0.05). Effect of the control with salbutamol (beta2-adrenergic receptor agonist) is efficient in the removal of the increased bronchomotor tone, causing significant decrease of the resistance (Raw), respectively of the specific resistance (SRaw), (p value 0.05 = Alpha 0.05).Conclusion:Formation of leukotrienes depends on the lypoxygenation of the arachidonic acid by 5-lypoxygenase. Zileuton is an active and powerful inhibitor of the activity of 5- lypoxygenase and as such inhibits generation of its products. Consequently, besides inhibition of cys-LTs’, zileuton also inhibits the formation of leukotriene B4 (LTB4), which is a powerful chemotactic of other eicosanoids too, which depend on the synthesis of lekotriene A4 (LTA4). This suggests that the effect of antileukotrienes (Zileuton) is not immediate after oral administration, but the powerful effect of the Zileuton seen only after two days of inhibition of cys-LTs’, and inhibition of leukotriene B4 (LTB4) and A4 (LTA4).

Favorable results from the use of herbal and plant products in inflammatory bowel disease: evidence from experimental animal studies.

The use of herbal therapy for inflammatory bowel disease is increasing worldwide. The aim of this study was to review the available literature on the efficacy of herbal therapy in experimental colitis. All relevant studies published in Medline and Embase up to June 2015 have been reviewed. The results of bowel histology and serum parameters have been recorded. A satisfactory number of published experimental studies, and a quite large one of both herbal and plant products tested in different studies have been reported. The results showed that in the majority of the studies, herbal therapy reduced the inflammatory activity of experimental colitis and diminished the levels of many inflammatory indices, including serum cytokines and indices of oxidative stress. The most promising plant and herbal products were tormentil extracts, wormwoodherb, Aloe vera, germinated barley foodstuff, curcumin, Boswellia serrata, Panax notoginseng, Ixeris dentata, green tea, Cordia dichotoma, Plantago lanceolata, Iridoidglycosides, and mastic gum. Herbal therapies exert their therapeutic benefit via various mechanisms, including immune regulation, anti-oxidant activity, inhibition of leukotriene B4 and nuclear factor-κB, and antiplatelet activity. Large, double-blind clinical studies assessing these natural substances should be urgently conducted.

Treatment with DHA/EPA ameliorates atopic dermatitis-like skin disease by blocking LTB4 production.

Atopic dermatitis (AD) is caused by both dysregulated immune responses and an impaired skin barrier. Although leukotriene B4 (LTB4) is involved in tissue inflammation that occurs in several disorders, including AD, therapeutic strategies based on LTB4 inhibition have not been explored. Here we demonstrate that progression of an AD-like skin disease in NC/Nga mice is inhibited when docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) is administered together with FK506. Treatment with DHA/EPA and FK506 decreases the clinical score of dermatitis in NC/Nga mice and lowers local LTB4 concentrations. The treatment also suppressed the infiltration of T cells, B cells, eosinophils and neutrophils, and promoted reduced serum IgE levels. Secretion of IL-13 and IL-17A in CD4(+) T cells was lower in DHA/EPA- and FK506-treated mice than in mice treated with FK506 alone. The inhibition of disease progression induced by DHA/EPA was reversed by local injection of LTB4, suggesting that the therapeutic effect of DHA/EPA is LTB4-dependent. Our results demonstrate that treatment of AD with DHA/EPA is effective for allergic skin inflammation and acts by suppressing LTB4 production. J. Med. Invest. 63: 187-191, August, 2016.

Naringenin and Atherosclerosis: A Review of Literature

Atherosclerosis is a multifactorial disease mainly caused by deposition of low-density lipoprotein (LD) cholesterol in macrophages of arterial walls. Atherosclerosis leads to heart attacks as well as stroke. Epidemiological studies showed that there is an inverse correlation between fruit and vegetable consumption and the risk of atherosclerosis. The promising effect of high vegetable and fruit containing diet on atherosclerosis is approved by several experimental studies on isolated phytochemicals such as flavonoids. Flavonoids are known to up-regulate endogenous antioxidant system, suppress oxidative and nitrosative stress, decrease macrophage oxidative stress through cellular oxygenase inhibition as well as interaction with several signal transduction pathways and from these ways, have therapeutic effects against atherosclerosis. Naringenin is a well known flavonoid belonging to the chemical class of flavanones. It is especially abundant in citrus fruits, especially grapefruits. A plethora of evidences ascribes to naringenin antiatherosclerotic effects. Naringenin abilities to decrease LDL and triglycerides as well as inhibit glucose uptake; increase high-density lipoprotein (HDL); co-oxidation of NADH; suppress protein oxidation; protect against intercellular adhesion molecule-1(ICAM-1); suppress macrophage inflammation; inhibit leukotriene B4, monocyte adhesion and foam cell formation; induce of HO-1 and G 0/G 1 cell cycle arrest in vascular smooth muscle cells (VSMC) and down regulate atherosclerosis related genes are believed to have crucial role in the promising role against atherosclerosis. In the present review, we have summarized the available literature data on the anti-atherosclerotic effects of naringenin and its possible mechanisms of action.

The novel 13S,14S‐epoxy‐maresin is converted by human macrophages to maresin 1 (MaR1), inhibits leukotriene A4hydrolase (LTA4H), and shifts macrophage phenotype

Maresins are produced by macrophages from docosahexaenoic acid (DHA) and exert potent proresolving and tissue homeostatic actions. Maresin 1 (MaR1; 7R,14S-dihydroxy-docosa-4Z,8E,10E,12Z,16Z,19Z-hexaenoic acid) is the first identified maresin. Here, we investigate formation, stereochemistry, and precursor role of 13,14-epoxy-docosahexaenoic acid, an intermediate in MaR1 biosynthesis. The 14-lipoxygenation of DHA by human macrophage 12-lipoxygenase (hm12-LOX) gave 14-hydro(peroxy)-docosahexaenoic acid (14-HpDHA), as well as several dihydroxy-docosahexaenoic acids, implicating an epoxide intermediate formation by this enzyme. Using a stereo-controlled synthesis, enantiomerically pure 13S,14S-epoxy-docosa-4Z,7Z,9E,11E,16Z,19Z-hexaenoic acid (13S,14S-epoxy-DHA) was prepared, and its stereochemistry was confirmed by NMR spectroscopy. When this 13S,14S-epoxide was incubated with human macrophages, it was converted to MaR1. The synthetic 13S,14S-epoxide inhibited leukotriene B4 (LTB4) formation by human leukotriene A4 hydrolase (LTA4H) ∼40% (P<0.05) to a similar extent as LTA4 (∼50%, P<0.05) but was not converted to MaR1 by this enzyme. 13S,14S-epoxy-DHA also reduced (∼60%; P<0.05) arachidonic acid conversion by hm12-LOX and promoted conversion of M1 macrophages to M2 phenotype, which produced more MaR1 from the epoxide than M1. Together, these findings establish the biosynthesis of the 13S,14S-epoxide, its absolute stereochemistry, its precursor role in MaR1 biosynthesis, and its own intrinsic bioactivity. Given its actions and role in MaR1 biosynthesis, this epoxide is now termed 13,14-epoxy-maresin (13,14-eMaR) and exhibits new mechanisms in resolution of inflammation in its ability to inhibit proinflammatory mediator production by LTA4 hydrolase and to block arachidonate conversion by human 12-LOX rather than merely terminating phagocyte involvement.

Complementary, Holistic, and Integrative Medicine

Complementary, Holistic, and Integrative Medicine