OBJECTIVETo investigate the effect of intracellular 5-lipoxygenase on oxidation of benzidine in HBE cells and to provide further evidence that lipoxygenase is an alternative pathway for the oxidation of xenobiotics mediated by cytochrome P450.

METHODSEnzyme system test: Soybean lipoxygenase (SLO), substrate (benzidine) and other components reacted in the enzyme system, followed by detection of the reaction products by spectrophotometry. In vitro test: After HBE cells were exposed to benzidine, the protein levels of 5-lipoxygenase in HBE cells were assessed by Western-blot, and the DNA damage by the single cell gel electrophoresis. At last, the effect of the specific inhibitor of 5-lipoxygenase (AA861) on 5-lipoxygenase protein expression and DNA damage in HBE cells were detected.

RESULTSSLO could catalyze the co-oxidation of benzidine to generate benzidine diimine in the presence of hydrogen peroxide. Under optimal condition, numax value of the oxidation of benzidine catalyzed by SLO was 1.42 nmol*min(-1) SLO, and the Km value of benzidine was 1.48 mmol/L. EGCG could inhibit the oxidation of benzidine by SLO. Benzidine could induce 5-lipoxygenase protein expression in HBE cells, but AA861 was invalid. Benzidine caused DNA damage in HBE cells, which could be significantly inhibited by AA861.

CONCLUSION5-LOX protein expression in HBE cells can be regulated by benzidine, which suggests that the co-oxidation of benzidine by 5-LOX could produce into electrophile that could covalently bind to DNA and induce DNA damage, which could be one of the mechanisms for carcinogenesis of BZD. 5-LOX inhibitor AA861 can inhibit this effect.

Arachidonate 5-Lipoxygenase ; metabolism ; Benzidines ; pharmacokinetics ; toxicity ; Cells, Cultured ; DNA Damage ; drug effects ; Epithelial Cells ; drug effects ; enzymology ; metabolism ; Humans

OBJECTIVETo determine whether 5-lipoxygenase (5-LOX) is involved in rotenone-induced injury in PC12 cells, which is a cell model of Parkinson disease.

METHODSAfter rotenone treatment for various durations, cell viability was determined by colorimetric MTT reduction assay, and 5-LOX translocation was detected by immunocytochemistry. The effect of 5-LOX inhibitor zileuton was also investigated.

RESULTRotenone (0.3-30 μmol/L) induced PC12 cell injury, and zileuton (3-100 μmol/L) attenuated this injury. Rotenone also time-and concentration-dependently induced 5-LOX translocation into the nuclear envelope, and zileuton (1-30 μmo/L) significantly inhibited rotenone-induced 5-LOX translocation.

CONCLUSION5-LOX is involved in rotenone-induced injury in PC12 cells, and 5-LOX inhibitor zileuton can reduce rotenone-induced 5-LOX activation and cell injury.

Animals ; Arachidonate 5-Lipoxygenase ; metabolism ; physiology ; Cell Survival ; drug effects ; Hydroxyurea ; analogs & derivatives ; pharmacology ; Lipoxygenase Inhibitors ; pharmacology ; PC12 Cells ; Rats ; Rotenone ; pharmacology

OBJECTIVETo determine 5-lipoxygenase (5-LOX) expression and the effect of zileuton, a selective 5-LOX inhibitor,on hippocampal neuron injury induced by global cerebral ischemia in rats.

METHODSGlobal cerebral ischemia was induced by bilateral common carotid artery occlusion combined with hypotension in rats. 5-LOX expression was detected by Western blot analyses and 5-LOX localization was visualized by immunohistochemistry and double immunofluorescence methods. The 5-LOX inhibitor zileuton (10, 30, 50 mg/kg) was orally administered for 3 d after ischemia.

RESULTSThe 5-LOX expression was increased in the ischemic hippocampus on d1-7 (peaked at d3), and 5-LOX protein was primarily localized in neurons and translocated to the nuclei in the hippocampal CA1 region after ischemia. The 5-LOX inhibitor zileuton (30, 50 mg/kg) reduced ischemia-induced hippocampal neurons death 3d after ischemia.

CONCLUSION5-LOX is involved in global cerebral ischemic damage in rats, and the 5-LOX inhibitor zileuton has a protective effect on neuronal damage in the rat hippocampus following global cerebral ischemia.

Animals ; Arachidonate 5-Lipoxygenase ; metabolism ; physiology ; Brain Ischemia ; metabolism ; pathology ; CA1 Region, Hippocampal ; metabolism ; pathology ; Disease Models, Animal ; Hydroxyurea ; analogs & derivatives ; pharmacology ; Lipoxygenase Inhibitors ; pharmacology ; Male ; Neurons ; drug effects ; pathology ; Rats ; Rats, Sprague-Dawley

BACKGROUNDAtherosclerosis is a kind of disease with multiple risk factors, of which hyperlipidemia is a major classical risk factor resulting in its pathogenesis and development. The aim of this study was to determine the effects of short-term intensive atorvastatin (IA) therapy on vascular endothelial function and explore the possible mechanisms that may help to explain the clinical benefits from short-term intensive statin therapy.

METHODSAfter exposure to high-fat diet (HFD) for 8 weeks, the animals were, respectively, treated with IA or low-dose atorvastatin (LA) for 5 days. Blood lipids, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide (NO), endothelin-1 (ET-1), and endothelium-dependent vasorelaxation function were, respectively, measured. mRNA and protein expression of CRP, TNF-α, IL-6, macrophage chemoattractant protein-1 (MCP-1), and 5-lipoxygenase (5-LO) were also evaluated in pericarotid adipose tissue (PCAT) and cultured adipocytes.

RESULTSHFD increased serum inflammatory factor levels; induced significant hyperlipidemia and endothelial dysfunction, including imbalance between NO and ET-1; enhanced inflammatory factors and 5-LO expression; and promoted macrophage infiltration into adipose tissue. Five-day IA therapy could significantly decrease serum inflammatory factor levels and their expression in PCAT; restore the balance between NO and ET-1; and improve endothelial function and macrophage infiltration without significant changes in blood lipids. However, all of the above were not observed in LA therapy. In vitro experiment found that lipopolysaccharide (LPS) enhanced the expression of inflammatory factors and 5-LO in cultured adipocytes, which could be attenuated by short-time (6 hours) treatment of high-dose (5 µmol/L) but not low-dose (0.5 µmol/L) atorvastatin. In addition, inhibiting 5-LO by Cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC, a potent and direct 5-LO inhibitor) could significantly downregulate the above-mentioned gene expression in LPS-treated adipocytes.

CONCLUSIONShort-term IA therapy could significantly ameliorate endothelial dysfunction induced by HFD, which may be partly due to attenuating inflammation of PCAT through inhibiting 5-LO pathway.

Adipose Tissue ; drug effects ; immunology ; Animals ; Arachidonate 5-Lipoxygenase ; metabolism ; Atorvastatin Calcium ; Heptanoic Acids ; therapeutic use ; Hyperlipidemias ; drug therapy ; immunology ; Inflammation ; drug therapy ; immunology ; Lipid Metabolism ; drug effects ; Male ; Pyrroles ; therapeutic use ; Rabbits

OBJECTIVETo investigate the effect of herba schizonepetae volatile oil (STO) on the activity of 5-lipoxygenase (5-LO), so as to elucidate its mechanisms of anti-inflammatory action which is related to the arachidonic acid (AA) metabolism.

METHODThoracic cavity leukocytes from the pleurisy model rat induced by injecting 1%-carrageenan into the pleural cavity were collected. Then 0. 4 mL cell suspension including 2 x 10(7) cells per millilitre were used as the reaction system in vitro. STO in different concentrations (final concentration 0.011, 0.022, 0.043, 0.087, 0.179, 0.255, 0.364 g x L(-1)), zileuton (final concentration 0.625 x 10(-3) g x L(-1)), and DMSO in the same volume were added into the reaction tube respectively. The reaction tubes were incubated at 37 degrees C for 20 min and CaCl2 (final concentration 2 mmol x L(-1)), MgCl2 (final concentration 0.5 mmol x L(-1)), exogenous AA (final concentration 200 micromol x L(-1)) and A23187 (final concentration 5 micromol x L(-1)) were added in turns during this period. The reaction tubes were mixed and continuously incubated at 37 degrees C for 30 min. After terminating reaction by adding methanol, the metabolites of 5-LO, leukotriene B4 (LTB4) and 5-hydroxy-6, 8, 11, 14-eicosatetraenoic acid (5-HETE), were extracted, separated and detected by means of RP-HPLC.

RESULTCompared with control group, STO significantly inhibited the biosynthesis of LTB4 and 5-HETE at final concentration between 0. 022 g x L(-1) and 0.364 g x L(-1) (P < 0.05 or 0.001) in dose dependence manner, and its IC50 value was 0.124 g x L(-1) and 0.142 g x L(-1) for LTB4 and 5-HETE, respectively.

CONCLUSIONSTO can inhibited the activity of 5-LO, which is an important enzyme of AA metabolism, in rat thoracic cavity leukocytes in a dose-dependent manner in vitro. It is suggested that the mechanism of anti-inflammatory action of STO is related to its inhibiting the activity of 5-LO and decreasing the level of major inflammatory mediators LTB4.

Animals ; Anti-Inflammatory Agents ; pharmacology ; Arachidonate 5-Lipoxygenase ; metabolism ; Cells, Cultured ; Drugs, Chinese Herbal ; pharmacology ; Leukocytes ; drug effects ; enzymology ; Male ; Oils, Volatile ; pharmacology ; Plant Oils ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Thoracic Cavity ; drug effects ; enzymology ; immunology

OBJECTIVETo explore the protective mechanisms of sevoflurane against acute lung injury (ALI) induced by one-lung ventilation (OLV) in view of cyclooxygenase-2 (COX2) and 5-lipoxygenase (5-LOX) pathways.

METHODEighteen healthy Japanese white rabbits were randomized into sham-operated group (S group), OLV group (O group) and OLV + sevoflurane group (OS group). COX2 and 5-LOX protein and mRNA expressions in the lungs were detected by Western blotting and real-time PCR, respectively. Prostaglandin I2 (PGI2), thromboxane A2 (TXA2) and leukotrienes B2 (LTB2) in the lung tissues were quantified with ELISA. Histological scores and lung wet/dry weight (W/D) ratios were determined for lung injury assessment.

RESULTSCOX2 and 5-LOX protein and mRNA expressions and the contents of LTB2, TXA2 and PGI2 in the lungs, lung W/D ratio and histological scores were significantly higher while PGI2/TXA2 ratio was significantly lower in O group and OS group than in S group (P<0.05). Compared with those in O group, COX2 and 5-LOX expressions, pulmonary contents of LTB2, TXA2 and PGI2, and lung W/D ratio all decreased significantly but PGI2/TXA2 ratio was significantly elevated in OS group (P<0.05).

CONCLUSIONOLV may activate COX2 and 5-LOX pathways to result in increased production of arachidonic acid metabolites. Sevoflurane protects against OLV-induced ALI probably by reducing AA metabolites and regulating PGI2/TXA2 ratio through inhibitions of COX2 and 5-LOX pathways.

Acute Lung Injury ; etiology ; metabolism ; Animals ; Arachidonate 5-Lipoxygenase ; metabolism ; Cyclooxygenase 2 ; metabolism ; Lung ; drug effects ; metabolism ; Methyl Ethers ; adverse effects ; One-Lung Ventilation ; adverse effects ; RNA, Messenger ; genetics ; Rabbits

OBJECTIVETo evaluate the translocation of 5-lipoxygenase (5-LOX)) after injuries by transfection with green fluorescence protein (GFP)/5-LOX in PC12 cells.

METHODSPC12 cells were stably transfected with pEGFP-C2/5-LOX (GFP/5-LOX) or pEGFP-C2 vectors (control). After treatment with oxygen-glucose deprivation (OGD), H(2)O(2) or NMDA, GFP/5-LOX localization in the cells was observed under a fluorescence microscope. Wild-type 5-LOX was determined by immunostaining after the treatment.

RESULTIn the GFP/5-LOX-transfected cells, GFP/5-LOX was primarily localized in the nucleus; while in the GFP-transfected cells, GFP was localized in both the cytoplasm and nucleus. After OGD and H(2)O(2) treatments, GFP/5-LOX was translocated to the nuclear membrane in 50.6 % and 57.7% cells respectively. However, after NMDA treatment or in GFP-transfected cells, no translocation was observed. Wild-type 5-LOX was distributed in the nuclei and cytoplasm, and all the 3 treatments induced 5-LOX translocation to the nuclear membrane.

CONCLUSIONIn the PC12 cells stably transfected with GFP/5-LOX, GFP/5-LOX is primarily distributed in the nuclei; the OGD-, H(2)O(2)- and NMDA-induced 5-LOX translocation exhibits different properties.

Animals ; Arachidonate 5-Lipoxygenase ; genetics ; metabolism ; Cell Nucleus ; metabolism ; Glucose ; pharmacology ; Green Fluorescent Proteins ; genetics ; metabolism ; Hydrogen Peroxide ; pharmacology ; Microscopy, Fluorescence ; N-Methylaspartate ; pharmacology ; Nuclear Envelope ; metabolism ; PC12 Cells ; Protein Transport ; drug effects ; Rats ; Recombinant Fusion Proteins ; genetics ; metabolism ; Transfection

BACKGROUND/AIMS: The major compounds of Cochinchina momordica seed extract (SK-MS10) include momordica saponins. We report that the gastroprotective effect of SK-MS10 in an ethanol-induced gastric damage rat model is mediated by suppressing proinflammatory cytokines and downregulating cytosolic phospholipase A2 (cPLA2), 5-lipoxygenase (5-LOX), and the activation of calcitonin gene-related peptide. In this study, we evaluated the gastroprotective effects of SK-MS10 in the nonsteroidal anti-inflammatory drug (NSAID)-induced gastric damage rat model. METHODS: The pretreatment effect of SK-MS10 was evaluated in the NSAID-induced gastric damage rat model using aspirin, indomethacin, and diclofenac in 7-week-old rats. Gastric damage was evaluated based on the gross ulcer index by gastroenterologists, and the damage area (%) was measured using the MetaMorph 7.0 video image analysis system. Myeloperoxidase (MPO) was measured by enzyme-linked immunosorbent assay, and Western blotting was used to analyze the levels of cyclooxygenase (COX)-1, COX-2, cPLA2, and 5-LOX. RESULTS: All NSAIDs induced gastric damage based on the gross ulcer index and damage area (p<0.05). Gastric damage was significantly attenuated by SK-MS10 pretreatment compared with NSAID treatment alone (p<0.05). The SK-MS10 pretreatment group exhibited lower MPO levels than the diclofenac group. The expression of cPLA2 and 5-LOX was decreased by SK-MS10 pretreatment in each of the three NSAID treatment groups. CONCLUSIONS: SK-MS10 exhibited a gastroprotective effect against NSAID-induced acute gastric damage in rats. However, its protective mechanism may be different across the three types of NSAID-induced gastric damage models in rats.
Animals ; Anti-Inflammatory Agents, Non-Steroidal/adverse effects ; Arachidonate 5-Lipoxygenase/drug effects ; Calcitonin Gene-Related Peptide/drug effects ; Cyclooxygenase 1/drug effects ; Cyclooxygenase 2/drug effects ; Disease Models, Animal ; Gastric Mucosa/chemistry/drug effects ; Group IV Phospholipases A2/drug effects ; Male ; Momordica/*chemistry ; Peroxidase/drug effects ; Plant Extracts/*pharmacology ; Rats ; Rats, Sprague-Dawley ; Seeds/*chemistry ; Stomach Ulcer/chemically induced/*prevention & control ; Treatment Outcome

BACKGROUND/AIMS: The unique role of enzyme 5-lipoxygenase (5-LO) in the production of leukotrienes makes it a therapeutic target for inflammatory bowel disease (IBD). The aim of this study was to evaluate the effects of B-98, a newly synthesized benzoxazole derivatives and a novel 5-LO inhibitor, in a mouse model of IBD induced by dextran sulfate sodium (DSS). METHODS: C57BL/6 mice were randomly assigned to four groups: normal control, DSS colitis (DSS+saline), low dose B-98 (DSS+B-98 20 mg/kg) and high dose B-98 (DSS+B-98 100 mg/kg). B-98 was administered with 3% DSS intraperitoneally. The severity of the colitis was assessed via the disease activity index (DAI), colon length, and histopathologic grading. The production of inflammatory cytokines interleukin (IL)-6 was determined by RT-PCR. Th cells were examined for the proportion of Th1 cell, Th2 cell, Th9 cell, Th17 cell and Treg cell using intracellular cytometry. RESULTS: The B-98 group showed lower DAI, less shortening of the colon length and lower histopathologic grading compared with the DSS colitis group (p<0.01). The expression of IL-6 in colonic tissue was significantly lower in the B-98 groups than the DSS colitis group (p<0.05). The cellular profiles revealed that the Th1, Th9 and Th17 cells were increased in the DSS colitis group compared to the B-98 group (p<0.05). CONCLUSIONS: Our results suggest that acute intestinal inflammation is reduced in the group treated with B-98 by Th1, Th9 and Th17 involved cellular immunity.
Acute Disease ; Animals ; Arachidonate 5-Lipoxygenase/chemistry/metabolism ; Benzoxazoles/chemistry/*pharmacology ; Colitis/chemically induced/pathology/*prevention & control ; Colon/drug effects/pathology/physiology ; Dextran Sulfate/toxicity ; Disease Models, Animal ; Forkhead Transcription Factors/metabolism ; Injections, Intraperitoneal ; Interleukin-6/genetics/metabolism ; Lipoxygenase Inhibitors/chemistry/*pharmacology ; Male ; Mice ; Mice, Inbred C57BL ; Severity of Illness Index ; T-Lymphocytes/classification/*drug effects/metabolism

Inflammatory diseases are common medical conditions seen in disorders of human immune system. There is a great demand for anti-inflammatory drugs. There are major inflammatory mediators in arachidonic acid metabolic network. Several enzymes in this network have been used as key targets for the development of anti-inflammatory drugs. However, specific single-target inhibitors can not sufficiently control the network balance and may cause side effects at the same time. Most inflammation induced diseases come from the complicated coupling of inflammatory cascades involving multiple targets. In order to treat these complicated diseases, drugs that can intervene multi-targets at the same time attracted much attention. The goal of this review is mainly focused on the key enzymes in arachidonic acid metabolic network, such as phospholipase A2, cyclooxygenase, 5-lipoxygenase and eukotriene A4 hydrolase. Advance in single target and multi-targe inhibitors is summarized.
Animals ; Anti-Inflammatory Agents ; therapeutic use ; Arachidonate 5-Lipoxygenase ; metabolism ; therapeutic use ; Arachidonic Acid ; metabolism ; Cyclooxygenase Inhibitors ; therapeutic use ; Drug Delivery Systems ; methods ; Epoxide Hydrolases ; antagonists & inhibitors ; metabolism ; therapeutic use ; Humans ; Inflammation ; drug therapy ; Lipoxygenase Inhibitors ; Metabolic Networks and Pathways ; drug effects ; Phospholipase A2 Inhibitors ; Phospholipases A2 ; metabolism ; therapeutic use ; Prostaglandin-Endoperoxide Synthases ; metabolism