Licofelone, a novel 5-LOX/COX-inhibitor, attenuates leukocyte rolling and adhesion on endothelium under flow

The main mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs) is the inhibition of cycloxygenases COX-1 and COX-2. During recent years, combined 5-LOX/COX-inhibition, interfering with the biosynthesis of both prostaglandins and leukotrienes (LTs), has emerged as a possibility to avoid side effects related to COX-inhibition. The aim of the present study was to investigate if there is a contribution of mechanisms other than the reduction of inflammatory prostaglandins and leukotrienes to the anti-inflammatory effect of the LOX/COX inhibitor licofelone. In a flow chamber assay, licofelone (10-30 microM) dose-dependently decreased both the rolling and adhesion of leukocytes on endothelial cells (EC). In contrast, no effects were found after treatment of EC with the unselective COX-1/COX-2 inhibitor indomethacin (30 microM), the potent and selective 5-LOX inhibitor, ZD-2138 (30 microM), the mainly COX-2 inhibitor aceclofenac (30 microM), the selective COX-2 inhibitor celecoxib (30 microM) and the combination of ZD-2138 with the selective COX-2 inhibitor celecoxib (30 microM). In the presence of licofelone (30 microM) the expression of E-selectin mRNA in cytokine-stimulated EC was attenuated, whereas no NSAID (30 microM) tested showed any effect on E-selectin expression. Moreover, licofelone treatment (30 microM) attenuated expression of VCAM-1 and ICAM-1 on inflammatory EC. The effect of licofelone on leukocyte recruitment was also evaluated in vivo. Using a mouse peritonitis model it was found that leukocyte accumulation was markedly reduced in licofelone treated animals (100mg/kg) compared to untreated mice. Thus, the novel 5-LOX/COX inhibitor licofelone possesses anti-inflammatory activity that, in addition to COX/LOX inhibition, involves effects on leukocyte-endothelial interactions.     

New anti-inflammatory treatment strategy in Alzheimer's disease

Numerous reports have indicated that patients suffering from inflammatory diseases (e.g., arthritis) who take anti-inflammatory medication have a reduced risk of developing Alzheimer's disease (AD). Thus, the first generation of anti-inflammatory cyclooxygenase (COX) inhibitors, such as aspirin and indomethacin, have been tested as potential therapeutics in AD. Because the inhibition of COX-1 is also known to cause tissue damage in the gastrointestinal system from the resultant reduced cytoprotection, selective COX-2 inhibitors are being investigated and tested clinically as potentially better therapeutics for AD patients. However, such drugs may also trigger unwanted effects; for example, the COX-2 inhibitors, which reduce the production of one type of eicosanoids, the prostaglandins, may increase the production of other eicosanoids; i.e., the leukotriene B4 (LTB4), which is one of the most potent endogenous chemotactic/inflammatory factors. LTB4 production is initiated by the enzyme 5-lipoxygenase (5-LOX). The expression of the 5-LOX gene is upregulated during neurodegeneration and with aging. In spite of the fact that 5-LOX and leukotrienes are major players in the inflammation cascade, their role in AD pathobiology/therapy has not been extensively investigated. We propose that the 5-LOX inflammatory cascade may take part in the process of aging-associated neurodegenerative diseases, and we point to the role of 5-LOX in neurodegeneration and discuss its relevance for anti-inflammatory therapy of AD.     

Lipoxin and synthetic lipoxin analogs: an overview of anti-inflammatory functions and new concepts in immunomodulation

Lipoxin A4 (LXA4) and lipoxin B4 (LXB4) were first identified in 1984 by Serhan and colleagues as 5- and 15-lipoxygenase interaction products of activated leukocytes. Endogenous transcellular biosynthesis of LXA4 and LXB4 occurs via interaction of leukocytes with epithelium, endothelium or platelets. Acetylation of cyclooxygenase-2 (COX-2) by aspirin can trigger 15-epi-LXA4 (ATL) biosynthesis. Elucidating the pharmacological actions of lipoxins and ATL was facilitated by total synthesis of LXA4 in 1988 by Nicolaou and colleagues. In 1994, Fiore and colleagues used [3H]-LXA4 to identify the cDNA for a human G-protein-coupled, high affinity LXA4 and ATL receptor (ALX-R/FPRL-1), providing the first hints for the molecular basis of lipoxin actions. The recognition that lipoxins and ATL undergo rapid, prostaglandin dehydrogenase (PGDH)-mediated metabolic inactivation led do the design and synthesis of first-generation PGDH-resistant LXA4, LXB4 and ATL analogs in 1995-1998 by Serhan, Petasis and colleagues. These relatively stable pharmacological agents, together with myeloid-specific ALX-R-expressing transgenic mice, have provided powerful tools to explore lipoxin functions in vivo. Here we briefly review the substantial body of evidence supporting the lipoxin --> ALX-R pathway as a novel and potent mechanism for preventing/resolving acute inflammation. Emphasis will also be placed on recent findings that lipoxins play new roles in "immunomodulation" via regulation of macrophage, dendritic cell, and T-lymphocyte effector functions in the setting of polarized T-helper cell responses (Th1 and Th2). These studies suggest roles for lipoxins as novel regulators of allergy and adaptive immunity and that lipoxins may have therapeutic potential in chronic immune disorders.     

Licofelone inhibits interleukin-18-induced pro-inflammatory cytokine release and cellular proliferation in human mesangial cells

Licofelone, a novel dual anti-inflammatory drug that inhibits 5-lipoxygenase (5-LOX) and cyclooxygenase (COX), has recently been defined to have therapeutic effects in osteoarthritis. Both 5-LOX and COX play functional roles in the pathogenesis of glomerulonephritis in children as well. Interleukin-18 is a pro-inflammatory cytokine. It remains unclear whether licofelone can ameliorate inflammatory response of human mesangial cells (HMC) exposed to interleukin-18. In this study, HMC were cultured and exposed to interleukin-18 with or without pre-treatment of licofelone. COX-2 and 5-LOX enzyme activities in mesangial cells were determined with chromometry or high-performance liquid chromatography. Prostaglandin E2, cysteinyl leukotriene, monocyte chemotactic protein-1 and interferon-γ concentrations in culture medium were measured using an enzyme-linked immunosorbent assay. Western blotting was employed to detect phosphorylated mitogen-activated protein kinases ERK1/2, p38 and JNK1/2 in HMC. It was found that licofelone attenuated interleukin-18-induced COX-2 enzyme activity in HMC and prostaglandin E2 release in a dose-dependent manner. Similarly, licofelone inhibited interleukin-18-induced 5-LOX enzyme activity and leukotriene release. Licofelone reduced interleukin-18-induced phosphorylation of p38 mitogen-activated protein kinase and suppressed monocyte chemotactic protein-1 and interferon-γ synthesis. Moreover, licofelone inhibited IL-18-induced proliferation of mesangial cells. We conclude that licofelone inhibits interleukin-18-induced pro-inflammatory cytokine release and cellular proliferation in HMC, which may represent a really interesting therapeutic approach for glomerulonephritis in children.     

Celecoxib inhibits 5-lipoxygenase

Celecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor used in the therapy of inflammatory and painful conditions. Various COX-2-independent pharmacological effects, such as a chemo-preventive and tumor-regressive activity have been suggested, but the respective non-COX-2 targets of celecoxib are still a matter of research. We now demonstrate that celecoxib inhibits 5-lipoxygenase (5-LO), a key enzyme in leukotriene (LT) biosynthesis. Celecoxib suppressed 5-LO product formation in ionophore A23187-activated human polymorphonuclear leukocytes (IC(50) approximately 8 microM). Similarly, celecoxib inhibited LTB(4) formation in human whole blood (IC(50) approximately 27.3 microM). Direct interference of 5-LO with celecoxib was visualized by inhibition of enzyme catalysis both in cell homogenates and with purified 5-LO (IC(50) approximately 23.4 and 24.9 microM, respectively). Related lipoxygenases (12-LO and 15-LO) were not affected by celecoxib. Other COX-2 inhibitors (etoricoxib and rofecoxib) or unselective NSAIDs (non-steroidal anti-inflammatory drugs, diclofenac) failed to inhibit 5-LO. In rats which received celecoxib (i.p.), the blood LTB(4) levels were dose-dependently reduced with an ED(50) value approximately 35.2 mg/kg. Together, celecoxib is a direct inhibitor of 5-LO in vitro and in vivo. These findings provide a potential molecular basis for some of the described COX-2-independent pharmacological effects of celecoxib.     

芒果苷对脂多糖诱导慢性炎症中环氧合酶/脂氧合酶的双重抑制作用

目的:探讨芒果苷对脂多糖(LPS)诱导慢性炎症中环氧合酶1/2(COX-1/2)、5脂氧合酶(5-LOX)的抑制作用。方法:60只SD大鼠随机分为对照组、模型组、泼尼松(PNS,5 mg.kg-1.d-1)组与芒果苷高、中、低剂量(MGFH/M/L,200,100和50 mg.kg-1.d-1)组,每组10只。对照组以外的各组大鼠每周1次尾静脉注射LPS(200μg.kg-1)建立慢性炎症模型,灌胃给药,共4周。第4周末以酶联免疫吸附法(ELISA)检测白细胞COX-1/2和5-LOX以及血清前列腺素E2/F2α(PGE2/F2α)、白三烯B4/C4/D4/E4(LT-B4/C4/D4/E4);RT-PCR检测白细胞COX-1/2和5-LOX基因表达。结果:与模型组比较,MGFH和MGFM组白细胞COX-2和5-LOX水平与基因表达以及血清PGE2/F2α和LT-B4/C4/D4/E4水平降低(P<0.01或0.05)。MGFH组白细胞COX-1水平与基因表达低于模型组(P<0.01)。结论:芒果苷对LPS诱导慢性炎症中COX-1/2与5-LOX均有抑制作用。     

Interaction of rofecoxib and celecoxib with warfarin.

The interaction of celecoxib and rofecoxib with warfarin was studied. Patients stable on warfarin therapy and concurrently taking a cyclooxygenase-2 (COX-2) inhibitor comparator (traditional nonsteroidal antiinflammatory medications, salsalate, or acetaminophen) randomly received celecoxib 200 mg/day or rofecoxib 25 mg/day for three weeks. After a one-week washout period, the patients were crossed over to treatment with the opposite COX-2 inhibitor for three more weeks. The International Normalized Ratio (INR) was measured at baseline and at weeks 1, 2, and 3 of therapy with each COX-2 inhibitor by testing blood samples obtained by finger stick. Data for 16 patients were analyzed. The INR increased by 13%, 6%, and 5% on average in patients taking celecoxib at weeks 1, 2, and 3, respectively, and by 5%, 9%, and 5% in patients taking rofecoxib. Changes in the INR were statistically significant at week 1 for celecoxib and at week 2 for rofecoxib. Of the 12 subjects who had a clinically significant > or = 15% change in the INR while receiving either COX-2 inhibitor, 4 showed this change for both agents. Adverse drug reactions were similar for each COX-2 inhibitor, but the rate of edema requiring medical intervention was higher in the rofecoxib group. Significant increases in the INR were observed in patients who were stable on warfarin therapy after the addition of therapy with rofecoxib or celecoxib.     

利克飞龙的抗炎作用研究

目的 研究利克飞龙的抗炎作用.方法 通过ig给药,观察利克飞龙对大小鼠的抗炎活性以及炎性因子水平.结果 ig利克飞龙(60 mg/kg)对小鼠耳肿胀及角叉菜胶引起大鼠足趾肿胀抑制作用与甲泼尼龙(60 mg/kg)相当,利克飞龙给药一周对小鼠体质量正常生长没有影响,利克飞龙对炎性因子前列腺素E2(PGE2)含量降低作用与塞来昔布相当.结论 利克飞龙具有高效的抗炎作用,其抗炎作用与甲泼尼龙相当,其降低PGE2作用与塞来昔布相当,且利克飞龙为COX/5-LOX双靶标抑制剂,理论上安全性更高,患者可长期服用,有望成为临床上非甾体抗炎药中的首选药物之一.     

Inhibitory activity of tryptanthrin on prostaglandin and leukotriene synthesis

The indolo[2,1- b]quinazoline alkaloid tryptanthrin has previously been identified as the cyclooxygenase-2 (COX-2) inhibitory principle in the extract ZE550 prepared from the medicinal plant Isatis tinctoria (Brassicaceae). We here investigated the potential inhibitory activity of tryptanthrin and ZE550 on COX-2, COX-1 in cellular and cell-free systems. A certain degree of selectivity towards COX-2 was observed when COX-1-dependent formation of thromboxane B(2) (TxB(2)) in HEL cells and COX-2-dependent formation of 6-ketoprostaglandin F(1alpha) (6-keto-PGF(1alpha)) in Mono Mac 6 and RAW 264.7 cells were compared. Preferential inhibition of COX-2 by two orders of magnitude was found in phorbol myristate acetate (PMA) activated bovine aortic coronary endothelial cells (BAECs). Assays with purified COX isoenzymes from sheep confirmed the high selectivity towards COX-2. The leukotriene B(4) (LTB(4)) release from calcium ionophore-stimulated human granulocytes (neutrophils) was used as a model to determine 5-lipoxygenase (5-LOX) activity. Tryptanthrin and the extract ZE550 inhibited LTB(4) release in a dose dependent manner and with a potency comparable to that of the clinically used 5-LOX inhibitor zileuton.     

Aspirin-triggered lipoxin in patients treated with aspirin and selective vs. nonselective COX-2 inhibitors

AIMS

Cyclooxygenase (COX)-2 inhibition has been reported to suppress the biosynthesis of the gastroprotective lipoxygenase metabolite 15(R)-epi-lipoxin A₄, also termed ‘aspirin-triggered lipoxin’ (ATL). We tested the hypothesis that the co-administration of aspirin with either the selective COX-2 inhibitor celecoxib or the nonselective COX inhibitor ibuprofen reduces ATL biosynthesis.

METHODS

We measured the urinary excretion of ATL in 24 patients with both ischaemic heart disease and osteoarthritis, chronically treated with aspirin and co-administered celecoxib 200 mg b.i.d., ibuprofen 600 mg t.i.d., or placebo for 7 days.

RESULTS

Baseline ATL was comparable in the three groups. On days 1 and 7, 4 h after co-administration of celecoxib or ibuprofen, ATL levels did not show significant variations (day 1: 0.24 ± 0.33, 0.26 ± 0.21 and 0.37 ± 0.22 ng mg⁻¹ creatinine, respectively; day 7: 0.21 ± 0.13, 0.35 ± 0.15 and 0.23 ± 0.18 ng mg⁻¹ creatinine, respectively).

CONCLUSIONS

Neither selective nor nonselective COX-2 inhibition appreciably interferes with ATL biosynthesis, suggesting that this mediator is not involved in exacerbating gastrotoxicity by the association of aspirin with COX-2 inhibitors.     

Design,synthesis, and biological evaluation of new pyrazoloquinazoline derivatives as dual COX-2/5-LOX inhibitors

A new series of pyrazoloquinazoline derivatives equipped with different chalcones was designed, synthesized, and identified through ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and infrared spectroscopic techniques. Our design strategy of the quinazolinone-privileged scaffold as a new scaffold was based on merging pharmacophores previously reported to exhibit cyclooxygenase-2 (COX-2)/5-lipoxygenase (5-LOX) inhibitory activity. All the newly synthesized derivatives were biologically evaluated for COX and 5-LOX inhibitory activity and COX-2 selectivity, using celecoxib and zileuton as reference drugs, as they exhibited promising anti-inflammatory activity. Compound 3j was found to be the most promising derivative, with IC₅₀ values of 667 and 47 nM against COX-1 and COX-2, respectively, which are superior to that of celecoxib (IC₅₀ value against COX-2 = 95 nM), showing an SI of 14.2 that was much better than celecoxib. Compounds 3f and 3h exhibited COX-1 inhibition, with IC₅₀ values of 1,485 and 684 nM, respectively. The synthesized compounds showed a significant inhibitory activity against 5-LOX, with IC₅₀ values ranging from 0.6 to 4.3 µM, where compounds 3f and 3h were found to be the most potent derivatives, with IC₅₀ values of 0.6 and 1.0 µM, respectively, in comparison with that of zileuton (IC₅₀ = 0.8 µM). These promising derivatives, 3f , 3h , and 3j , were further investigated in vivo for anti-inflammatory, gastric ulcerogenic effects, and prostaglandin production (PGE2) in rat serum. The molecular docking studies concerning the binding sites of COX-2 and 5-LOX revealed similar orientation, compared with reported inhibitors, which encouraged us to design new leads targeting COX-2 and 5-LOX as dual inhibitors, as a new avenue in anti-inflammatory therapy.     

Synthesis and structure-activity relationship studies of 1,3-diarylprop-2-yn-1-ones: dual inhibitors of cyclooxygenases and lipoxygenases

A group of 1,3-diarylprop-2-yn-1-ones (13, 17, 23, 26 and 27) possessing a C-3 p-SO2Me COX-2 pharmacophore were designed, synthesized and evaluated as potential dual inhibitors of cyclooxygenase-1/2 (COX-1/2) and 5/15-lipoxygenases (5/15-LOX) that exhibit vivo antiinflammatory and analgesic activities. Among this class of compounds, 3-(4-methanesulfonylphenyl)-1-(4-fluorophenyl)prop-2-yn-1-one (13h) was identified as a potent and selective inhibitor of COX-2 (COX-2 IC50 = 0.1 microM; SI = 300), being 5-fold more potent than rofecoxib (COX-2 IC50 = 0.5 microM; SI > 200). In a rat carrageenan-induced paw edema assay 13h exhibited moderate antiinflammatory activity (26% inhibition of inflammation) at 3 h after administration of a 30 mg/kg oral dose. A related dual COX-1/2 and 5/15-LOX inhibitor 3-(4-methanesulfonylphenyl)-1-(4-cyanophenyl)prop-2-yn-1-one (13g, COX-1 IC50 = 31.5 microM; COX-2 IC50 = 1.0 microM; SI = 31.5; 5-LOX IC50 = 1.0 microM; 15-LOX IC50 = 3.2 microM) exhibited more potent antiinflammatory activity (ED50 = 90 mg/kg), being superior to the reference drug aspirin (ED50 = 129 mg/kg). Within this group of compounds 3-(4-methanesulfonylphenyl)-1-(4-isopropylphenyl)prop-2-yn-1-one (13e) emerged as having an optimal combination of in vitro COX-1/2 and 5/15-LOX inhibitory effects (COX-1 IC50 = 9.2 microM; COX-2 IC50 = 0.32 microM; SI = 28; 5-LOX IC50 = 0.32 microM; 15-LOX IC50 = 0.36 microM) in conjunction with a good antiinflammatory activity (ED50 = 35 mg/kg) compared to the reference drug celecoxib (ED50 = 10.8 mg/kg) when administered orally. A molecular modeling study where 13e was docked in the COX-2 binding site indicated the C-1 p-i-Pr group was positioned within a hydrophobic pocket (Phe205, Val344, Val349, Phe381 and Leu534), and that this positioning of the i-Pr group facilitated orientation of the C-3 p-SO2Me COX-2 pharmacophore such that it inserted into the COX-2 secondary pocket (His90, Arg513, Ile517 and Val523). A related docking study of 13e in the 15-LOX binding site indicates that the C-3 p-SO2Me COX-2 pharmacophore was positioned in a region closer to the catalytic iron site where it undergoes a hydrogen bonding interaction with His541 and His366, and that the C-1 p-i-Pr substituent is buried deep in a hydrophobic pocket (Ile414, Ile418, Met419 and Ile593) near the base of the 15-LOX binding site.     

Synthesis and biological evaluation of pyrazolone analogues as potential anti-inflammatory agents targeting cyclooxygenases and 5-lipoxygenase

New pyrazolone derivatives structurally related to celecoxib and FPL 62064 were synthesized and biologically evaluated for their inhibitory activity against cyclooxygenases (COXs) and 5-lipoxygenase (5-LOX) and their selectivity indices were calculated. The results showed that compounds 3f , 3h , 3l , and 3p have an excellent COX-2 selectivity index. Moreover, they showed potent 5-LOX inhibitory activity relative to celecoxib and zileuton, as positive controls. These promising candidates were further investigated for anti-inflammatory activity using the carrageenan-induced rat paw edema method and ulcerogenic liability. The results showed no ulceration, which implies their gastric safety profile. Moreover, these compounds were evaluated for prostaglandin (PGE2) production in rat serum. Molecular docking in the COX-2 and 5-LOX active sites was performed to rationalize their anti-inflammatory activities. Strong binding interactions and effective docking scores were identified. The results indicated that these derivatives are good leads for dual-acting COX-2/5-LOX inhibitors to be used as potent and safe anti-inflammatory agents.     

Prostaglandin E2 inhibits and indomethacin and aspirin enhance, A23187-stimulated leukotriene B4 synthesis by rat peritoneal macrophages

1. The calcium ionophore, A23187, stimulated leukotriene B4 (LTB4), thromboxane B2 (TxB2) and prostaglandin E2 (PGE2) synthesis by 4 day carrageenin-elicited rat peritoneal macrophages. 2. At concentrations of 2 x 10(-7)-2 x 10(-5) M indomethacin and aspirin enhanced A23187-stimulated LTB4 synthesis and inhibited PGE2 and TXB2 formation. 3. PGE2 inhibited A23187-stimulated LTB4 and TXB2 formation as well as the augmentation of LTB4 release caused by aspirin and indomethacin. However, PGE2 was ineffective when the cells were challenged with arachidonic acid (AA). 4. Dibutyryl adenosine 3':5'-cyclic monophosphate (db-cyclic AMP) partially inhibited A23187-stimulated LTB4 production. 5. Our results suggest that PGE2 inhibits macrophage LTB4 synthesis by limiting the availability of AA. Indomethacin and aspirin, possibly by removing the regulatory effect of PGE2, promote the synthesis of the pro-inflammatory LTB4.     

Stimulation of protein kinase C redistribution and inhibition of leukotriene B4-induced inositol 1,4,5-trisphosphate generation in human neutrophils by lipoxin A4.

1. To test the hypothesis that protein kinase C (PKC) is involved in the inhibitory actions of lipoxin A4 (LXA4) on second messenger generation, we studied the effects of LXA4 on PKC in human neutrophils and on leukotriene B4 (LTB4)-stimulated inositol-1,4,5-trisphosphate (Ins(1,4,5)P3) generation. 2. LXA4, 1 microM, caused a fall in cytosolic PKC-dependent histone phosphorylating activity to 23.5% of basal levels. 3. LXA4, caused an increase in particulate PKC-dependent histone phosphorylating activity with a bell-shaped dose-response fashion; maximal stimulation was observed at 10 nM LXA4. 4. Western blot analysis with affinity-purified antibodies to alpha- and beta-PKC showed that only the beta-PKC isotype was translocated by LXA4. 5. LXA4 inhibited LTB4-stimulated Ins(1,4,5)P3 generation in a bell-shaped fashion with maximal inhibition at 1 nM LXA4. The observed inhibition was dose-dependently removed by pre-incubation with a PKC inhibitor (Ro-31-8220). 6. These results show that LXA4 activates PKC in whole cells and supports a role for PKC activation in the inhibitory action of LXA4 on LTB4-induced Ins(1,4,5)P3 generation. 7. LXA4 (1-1000 nM) pre-incubation did not affect specific binding of [3H]-LTB4 to neutrophils. Thus, the inhibitory effect of LXA4 on LTB4-stimulated Ins(1,4,5)P3 generation could not be attributed to an effect on LTB4 receptors.     

Drug switching patterns among patients with rheumatoid arthritis and osteoarthritis using COX-2 specific inhibitors and non-specific NSAIDs

PURPOSE: To compare RA and OA patients' time-to-switch after newly initiating treatment with three most commonly used non-specific (NS)-NSAIDs and two COX-2 inhibitors, celecoxib and rofecoxib. METHODS: Managed care enrollees newly prescribed celecoxib, rofecoxib, ibuprofen, naproxen or diclofenac were identified. Time to switch to a different NS-NSAID or COX-2 specific inhibitor was determined using time-to-event analysis and Cox proportional hazards models were used to estimate the odds ratio (OR) after controlling for potential confounders. RESULTS: The time to 25% of the cohort switching was longer for rofecoxib and celecoxib (159 and 205 days respectively) compared to the three NS-NSAIDs (49-78 days). Patients were at the highest risk of switching within the first 100 days of therapy. After adjusting for potential confounding factors, the OR for switching to another NS-NSAID or COX-2 specific inhibitor ranged from 1.74 to 2.35 for the three NS-NSAIDs compared to celecoxib (all comparisons, p < 0.01). Similar findings were obtained when comparing rofecoxib to each of the three NS-NSAIDS (all comparisons, p < 0.01). When COX-2 inhibitors combined were compared to NS-NSAIDS combined, the OR for switching was 1.53 (95% confidence interval = 1.42-1.65; p < 0.01) after adjusting for potential confounders. CONCLUSIONS: Patients on the COX-2 specific inhibitors (celecoxib and rofecoxib) were significantly less likely to switch their therapy than patients on NS-NSAIDS (ibuprofen, naproxen and diclofenac). These results suggest that COX-2 specific inhibitors may be a more effective treatment option when compared with NS-NSAIDs in usual clinical practice.     

Covalent binding of rofecoxib, but not other cyclooxygenase-2 inhibitors, to allysine aldehyde in elastin of human aorta.

In rats, it has been reported that rofecoxib, a cyclooxygenase-2 (COX-2) inhibitor, reacts with the aldehyde group of allysine in elastin to give a condensation covalent adduct, thereby preventing the formation of cross-linkages in the elastin and causing degradation of the elastic fibers in aortas in vivo. Acid, organic solvent, and proteolytic enzyme treatments of human aortic homogenate after incubation with [(14)C]rofecoxib demonstrated that most of the radioactivity is covalently bound to elastin. The in vitro covalent binding was inhibited in the presence of beta-aminopropionitrile, D-penicillamine, and hydralazine, which suggested that the aldehyde group of allysine in human elastin was relevant to the covalent binding. The in vitro covalent binding of [(14)C]rofecoxib was significantly decreased by the addition of only nonradiolabeled rofecoxib but not the other COX-2 inhibitors, celecoxib, valdecoxib, etoricoxib, and CS-706 [2-(4-ethoxyphenyl)-4-methyl 1-(4-sulfamoylphenyl)-1H-pyrrole], a novel selective COX-2 inhibitor. All the above COX-2 inhibitors except for rofecoxib had no reactivity with the aldehyde group of benzaldehyde used as a model compound of allysine aldehyde under a physiological pH condition. On the other hand, no retention of the radioactivity of [(14)C]rofecoxib was observed in human aortic endothelial cells in vitro, suggesting that rofecoxib is not retained in aortic endothelial cells in vivo. These results suggest that rofecoxib, but not other COX-2 inhibitors, is capable of covalently binding to the aldehyde group of allysine in human elastin. This might be one of the main causes of cardiovascular events by rofecoxib in clinical situations.     

Dynamic modeling of human 5-lipoxygenase-inhibitor interactions helps to discover novel inhibitors

Human 5-lipoxygenase (5-LOX) is one of the key anti-inflammatory drug targets due to its key role in leukotrienes biosynthesis. We have built a model for the active conformation of human 5-LOX using comparative modeling, docking of known inhibitors, and molecular dynamics simulation. Using this model, novel 5-LOX inhibitors were identified by virtual screen. Of the 105 compounds tested in a cell-free assay, 30 have IC(50) values less than 100 μM and 11 less than 10 μM with the strongest inhibition of 620 nM. Compounds 4, 7, and 11 showed strong inhibition activity in the human whole blood (HWB) assay with IC(50) values of 8.6, 9.7, 8.1 μM, respectively. Moreover, compounds 4 and 7 were also found to inhibit microsomal prostaglandin E synthase (mPGES)-1 with micromolar IC(50) values, similar to licofelone, a dual functional inhibitor of 5-LOX/mPGES-1. The compounds reported here provide new scaffolds for anti-inflammatory drug design.     

Further phenols and polyacetylenes from the rhizomes of Atractylodes lancea and their anti-inflammatory activity

From the rhizomes of Atractylodes lancea, 2-[(2'E)-3',7'-dimethyl-2',6'-octadienyl]-4-methoxy-6-methylphenol (1) was isolated as a new natural product. The compound showed strong inhibitory effects on 5-lipoxygenase (5-LOX) and cyclooxygenase-1 (COX-1), but exhibited only weak antioxidative activities [IC50 = 0.1 microM (5-LOX), 2 microM (COX-1), 9 microM (PMN/FMLP), 28 microM (PMNIOZ)]. Moreover, five new acetylenes were isolated and elucidated as (3Z,5E,11E)-tridecatriene-7,9-diynyl-1-O-(E)-ferulate (2), erythro-(1,3Z,11E)-tridecatriene-7,9-diyne-5,6-diyl diacetate (3), (1Z)-atractylodin (4), (1Z)-atractylodinol (5), (1Z)-acetylatractylodinol (6) plus the known (4E,6E,12E)-tetradecatriene-8,10-diyne-1,3-diyl diacetate (7). Among the acetylenes, only 2 showed strong inhibition of 5-LOX and COX-1 activity (IC50 (5-LOX) = 3 microM, IC50 (COX-1) = 1 microM). In addition, the fatty acids linoleic acid, oleic acid and palmitic acid with previously established 5-LOX-/COX-1 inhibitory actions were identified as major constituents of the n-hexane extract and thus seem to contribute to the plant's in vitro activity.     

ZLJ-6, a novel COX/5-LOX inhibitor, attenuates TNF-α-induced endothelial E-selectin, ICAM-1 and VCAM-1 expression and monocyte-endothelial interactions via a COX/5-LOX-independent mechanism

Nonsteroidal anti-inflammatory drugs (NSAIDs) are previously found to possess prostaglandin and leukotriene-independent anti-inflammatory effect. The aim of the present study was to investigate the prostaglandin and leukotriene-independent anti-inflammatory effect of an imidazolone COX/5-LOX inhibitor ZLJ-6 and the underlying mechanism. Pretreatment human umbilical vein endothelial cells (HUVECs) with ZLJ-6 (3, 10 and 30μM) concentration-dependently decreased TNF-α-induced monocyte-endothelial interactions in both static and dynamic conditions whereas no effect was found after pretreatment with the COX-2 inhibitor celecoxib (30μM), 5-LOX inhibitor zileuton (30μM) and the combination of them. ZLJ-6 also attenuated expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cytoadhesion molecule-1 (VCAM-1) on TNF-α-induced HUVECs. A further analysis indicated that ZLJ-6 attenuated TNF-α-induced nuclear translocation of NF-κB, IκB phosphorylation, IκB kinase β (IKKβ) activity, and subsequent NF-κB-DNA complex formation, suggesting that NF-κB pathway was involved in TNF-α-induced inflammation. However, ZLJ-6 did not affect TNF-α-induced extracellular signal-regulated kinases (ERK1/2), c-Jun N-terminal kinases (JNK) and p38 phosphorylation. Taken together, our results indicated that ZLJ-6 potently inhibited TNF-α-induced monocyte-endothelial interactions and adhesion molecule (E-selectin, ICAM-1 and VCAM-1) expression and these effects were mediated by NF-κB signaling pathway rather than its primary pharmacological target COX-2 or 5-LOX.