FLAP/5-lipoxygenase-activating protein (IC50 = 1.6 nM)
Quiflapon sodium targets 5-lipoxygenase-activating protein (FLAP), an integral membrane protein that is required for the activity of 5-lipoxygenase (5-LOX). FLAP is responsible for the transfer of arachidonic acid to 5-LOX, the enzyme that catalyzes the first two steps in the biosynthesis of leukotrienes, which are potent pro-inflammatory lipid mediators. By inhibiting FLAP, Quiflapon sodium prevents the production of leukotrienes, reducing inflammation. The compound has an IC50 of 1.6 nM in a FLAP binding assay.

SB203580 and Quiflaponodium (MK591) prevent human PBMC cells from proliferating when exposed to SEB. Three genes that are increased by SEB—cathepsin L, IL-17, and guanylate binding protein (GBP)-2—are downregulated by quilaponodium (MK591) [1]. Treatment with quiflapon sodium (MK591) causes apoptosis within hours. Additionally, quilaponodium causes the stress kinase c-Jun N-terminal kinase (JNK) to activate quickly. JNK is crucial to the process of apoptosis. Prostate cancer cells undergo apoptosis when exposed to quilapon sodium, however PI3K-Akt or ERK are not inhibited. Furthermore, Quifflapon sodium and LY294002 work in concert to cause prostate cancer cells to undergo apoptosis [2]. Sp1 is unaffected by quilapon sodium (MK591), but the cAMP response element binding protein is[4].

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In vitro, Quiflapon sodium demonstrates potent inhibition of FLAP with an IC50 of 1.6 nM in a FLAP binding assay. As a FLAP inhibitor, the compound effectively blocks leukotriene biosynthesis. The compound's potency and selectivity for FLAP make it a valuable tool for studying the role of leukotrienes in inflammatory diseases. Specific cellular assay data, such as IC50 values for inhibition of leukotriene production in cells, are not detailed in the available sources.

In contrast to the untreated hyperoxia group, the mice in the hyperoxia group given Quiflapon sodium (MK591) (20, 40 mg/kg) demonstrated aberrant alveolarization, while the alveolarization in the treated group resembled that of room air controls. However, no inflammation is present [3]. When Aβ immunopositive areas from placebo and Quiflapon sodium (MK591) (320 mg/kg) treatment groups were compared, the treated mice's amyloid load was statistically significantly lower. Moreover, quilapon sodium dramatically lowers brain levels of IL-1β. The steady-state levels of overall CREB and its Ser133 phosphorylated version were statistically significantly lower in mice given Quiflapon sodium [4].

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Specific in vivo activity data for Quiflapon sodium are not detailed in the available sources. As a FLAP inhibitor, the compound is expected to have anti-inflammatory activity in vivo by reducing leukotriene production. FLAP inhibitors have been studied for the treatment of inflammatory and allergic diseases, such as asthma and atherosclerosis. However, specific animal model studies have not been described in the available literature. The compound is intended for research use only.

MK591 is a synthetic compound which specifically inhibits the activity of 5-Lox and is currently under development for the treatment of asthma. We observed that human prostate cancer cells treated with MK591 undergo apoptosis within hours of treatment. Apoptosis involves severe morphological alteration, externalization of phosphatidyl-serine, cleavage of PARP, and degradation of chromatin-DNA. MK591 also induced rapid activation of the stress kinase, c-Jun N-terminal kinase (JNK), which plays an important role in the apoptosis process. The phosphatidylinositol 3'-kinase-Akt/protein kinase B (PI3K/Akt) axis is a well-known pro-survival pathway which prevents apoptosis through defined anti-apoptotic mechanisms in a variety of cancer cells. Interestingly, we observed that MK591 triggers apoptosis in prostate cancer cells without inhibition of PI3K-Akt, or ERK. Moreover, it was observed that MK591 and LY294002 (an inhibitor of PI3K) exert synergistic effect in inducing apoptosis in prostate cancer cells. Altogether, these findings indicate that 5-Lox inhibition-induced apoptosis in prostate cancer cells occurs without inhibition of PI3K-Akt, or ERK, and suggest for the existence of an Akt- and ERK-independent survival mechanism(s) in these cancer cells maintained via signals generated by metabolites of 5-Lox.[2]

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A series of performed inhibitor studies identified a specific inhibitor of 5-LO (MK591), which has the ability to block JNK, MAPK, p38kinase and 5-LO signaling-cascades and drastically reducing the activity of pro-inflammatory cytokine TNF-alpha. Further evaluation of MK591 utilizing cell proliferation assays in PBMCs, human proximal tubule cells and in vivo studies (monkey) showed a decrease in cell proliferation. The inhibitory effect of MK591 was reconfirmed at a genetic level through the utilization of a set of SEB specific genes. Signaling activities, inhibitor studies, cellular analysis and gene expression analysis in unison illustrated the significance of pathway interconnectors such as 5-LO as well as inhibiting such inter-connectors (using MK591) in SEB induced human PBMCs.[1]

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The FLAP binding assay for Quiflapon sodium involves incubating the compound with membrane preparations from cells expressing human FLAP and a radiolabeled FLAP ligand. After incubation, bound and free ligands are separated by filtration, and the radioactivity is counted. The IC50 for displacement of the radioligand is calculated from the competition curve. The compound's ability to inhibit FLAP function can be assessed by measuring leukotriene production in cells or cell-free systems.

For each experiment, equal numbers of cells were plated in six-well plates; 24 h later media were removed and fresh media containing either MK-591 (1 μM, 10 μM or 25 μM) or vehicle were added. After incubation for 24 h, supernatants were collected for Aβ and LDH measurement, and cell pellets harvested in lytic buffer for immunoblot analyses as described in the previous paragraphs. For transfection studies, N2A-APPswe cells were transfected with 1 μg Myc-tagged mΔE-Notch-1 complementary DNA overnight by using Lipofectamine 2000 (Invitrogen). The media were removed and fresh media containing MK-591, L685,458 or vehicle were added. After incubation for 24 h, cells lysates were collected NICD expression levels assayed by western blot analysis.[4]

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To evaluate the cellular activity of Quiflapon sodium, cells that produce leukotrienes (such as human polymorphonuclear leukocytes or mast cells) are treated with varying concentrations of the compound and stimulated with a calcium ionophore (such as A23187) to induce leukotriene production. The levels of leukotrienes (such as LTB4 or LTC4) in the cell supernatant are measured using ELISA or LC-MS/MS. The IC50 for inhibition of leukotriene production is calculated. Cell viability is monitored to ensure that observed effects are not due to cytotoxicity.

Starting at 7 months of age, mice were randomized to receive MK-591 (40 mg/kg weight) (n = 11) or vehicle (n = 9) in their chow diet for 8 months until they were 15 months old. Considering that each mouse eats on average 5 g/day of chow diet and the diet is formulated for 320 mg MK-591 per kg diet (Harlan Teklad, WI, USA), the final dose of the active drug was approximately 40 mg/kg weight/day. During the study, mice in both groups gained weight regularly, and no significant difference in weight was detected between the two groups. No macroscopic effect on the overall general health was observed in the animals receiving the active treatment. Post-mortem examination showed no sign of macroscopic pathology in any of the organs considered (spleen, liver, thymus, ileum).[4]

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Specific in vivo animal experiment protocols for Quiflapon sodium are not detailed in the available sources. As a FLAP inhibitor, the compound would typically be evaluated in animal models of inflammation, such as carrageenan-induced paw edema, zymosan-induced peritonitis, or ovalbumin-induced airway inflammation. Animals would be treated with Quiflapon sodium orally or intraperitoneally, and inflammatory parameters (such as edema, leukocyte infiltration, and leukotriene levels) would be measured. However, specific protocols are not described in the available literature.

Specific pharmacokinetic data for Quiflapon sodium are not provided in the available sources. The compound is a small molecule with a molecular weight of 609.15 and a molecular formula of C34H34ClN2NaO3S. It is the sodium salt form of Quiflapon, which may enhance its solubility. Standard pharmacokinetic studies would typically involve administering the compound to rodents and measuring plasma concentrations over time using LC-MS/MS to determine key PK parameters.

Specific toxicity data for Quiflapon sodium are not provided in the available sources. As a research compound, it is intended for laboratory use only and is not approved for human therapeutic applications. Standard safety precautions should be followed when handling this compound, including the use of appropriate personal protective equipment.

[1]. Effect of 5-lipoxygenase inhibitor MK591 on early molecular and signaling events induced by staphylococcal enterotoxin B in human peripheral blood mononuclear cells. FEBS J. 2008 Jun;275(12):3088-98.

[2]. MK591, a leukotriene biosynthesis inhibitor, induces apoptosis in prostate cancer cells: synergistic action with LY294002, an inhibitor of phosphatidylinositol 3'-kinase. Cancer Lett. 2010 May 28;291(2):167-76.

[3]. 5-Lipoxygenase-activating protein (FLAP) inhibitor MK-0591 prevents aberrant alveolarization in newborn mice exposed to 85% oxygen in a dose- and time-dependent manner. Lung. 2011 Feb;189(1):43-50.

[4]. Involvement of 5-lipoxygenase activating protein in the amyloidotic phenotype of an Alzheimer's disease mouse model. J Neuroinflammation. 2012 Jun 14;9:127.

MK-0591 (3-[1-(4-chlorobenzyl)-3-(tert-butylthio)-5-(quinolin-2-yl-methoxy)-indol-2-yl]-2,2-dimethylpropionic acid, formerly known as L-686,708) is a potent inhibitor of leukotriene (LT) biosynthesis in intact human polymorphonuclear leukocytes (PMNLs) and induced rat polymorphonuclear leukocytes (PMNLs) (IC50 values of 3.1 nM and 6.1 nM, respectively). It also exhibits inhibitory activity in whole blood from humans, squirrel monkeys, and rats (IC50 values of 510 nM, 69 nM, and 9 nM, respectively). MK-0591 has no effect on rat 5-lipoxygenase. MK-0591 exhibits a high affinity for 5-lipoxygenase-activated protein (FLAP), with an IC50 value of 1.6 nM in the FLAP binding assay, and this is confirmed by its ability to inhibit photoaffinity labeling of FLAP by two different photoaffinity ligands. In human polymorphonuclear leukocytes (PMNL), the inhibitory effect of MK-0591 on 5-lipoxygenase activation was demonstrated by inhibiting the translocation of 5-lipoxygenase from the cytosol to the cell membrane. MK-0591 is a potent in vivo inhibitor of leukotriene (LT) biosynthesis, as demonstrated firstly by in vitro stimulation of the blood of rats and squirrel monkeys treated with MK-0591; secondly, by a rat pleurisy model; and thirdly, by inhibiting the excretion of LTE4 in the urine of antigen-induced allergic sheep. The inhibitory effect of MK-0591 on antigen-induced bronchoconstriction was observed in inbred rats pretreated with lysergic acid diethylamine, squirrel monkeys infected with Ascaris lumbricoides, and sheep infected with Ascaris lumbricoides (early and late responses). These results indicate that MK-0591 is a potent inhibitor of leukotriene biosynthesis in vitro and in vivo, suggesting that this compound is suitable for evaluating the role of leukotrienes in pathological conditions. Canadian Journal of Physiology and Pharmacology, June 1992; 70(6):799-807.

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Bronchopulmonary dysplasia is characterized by chronic oxygen dependence due to impaired gas exchange capacity. This is mainly attributed to alveolar hypoplasia and abnormalities caused by damage such as hyperoxia. Leukotrienes are associated with hyperoxia-induced alveolar development inhibition. We hypothesized that administration of a 5-lipoxygenase-activating protein (FLAP) inhibitor to newborn mice exposed to 85% oxygen could prevent abnormal alveolarization in a dose- and time-dependent manner. Newborn mice were exposed to normal air or a hyperoxia environment for 14 days, respectively. Young mice were administered either the excipient or MK-0591 (10, 20, or 40 mg/kg) subcutaneously once daily for 1–4, 5–9, or 10–14 days, respectively. On day 14, lung tissue was inflated, fixed, and stained for histopathological and morphometric analysis. Mice in the hyperoxia group treated with MK-0591 (20 or 40 mg/kg) on days P1–P4 or P10–P14 showed alveolarization similar to the normal air control group, while untreated hyperoxia mice exhibited markedly abnormal alveolarization without inflammatory response. In a neonatal mouse model exposed to hyperoxia, administration of FLAP inhibitors during the critical window period dose- and time-dependently prevented abnormal alveolar development. Lung. 2011 Feb; 189(1):43–50.

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Quiflapon sodium is also known as L-686,70 sodium, MK591 sodium, and MK-591. It is a novel, potent, selective, and specific 5-lipoxygenase-activating protein (FLAP) inhibitor with an IC50 of 1.6 nM in a FLAP binding assay. The compound has a molecular formula of C34H34ClN2NaO3S and a molecular weight of 609.15. It is used in research related to leukotriene biosynthesis and inflammation.

C34H34N2O3SCL-.NA+

609.15316

608.188

C, 67.04; H, 5.63; Cl, 5.82; N, 4.60; Na, 3.77; O, 7.88; S, 5.26

147030-01-1

Quiflapon;136668-42-3

23672584

Typically exists as White to off-white solids at room temperature

751.3ºC at 760mmHg

408.2ºC

1.03E-23mmHg at 25°C

7.679

0

5

10

42

879

0

[O-]C(C(C)(C)CC(N1CC2=CC=C(Cl)C=C2)=C(SC(C)(C)C)C3=C1C=CC(OCC4=NC5=CC=CC=C5C=C4)=C3)=O.[Na+]

YPURUCMVRRNPHJ-UHFFFAOYSA-M

InChI=1S/C34H35ClN2O3S.Na/c1-33(2,3)41-31-27-18-26(40-21-25-15-12-23-8-6-7-9-28(23)36-25)16-17-29(27)37(20-22-10-13-24(35)14-11-22)30(31)19-34(4,5)32(38)39;/h6-18H,19-21H2,1-5H3,(H,38,39);/q;+1/p-1

sodium 3-(3-(tert-butylthio)-1-(4-chlorobenzyl)-5-(quinolin-2-ylmethoxy)-1H-indol-2-yl)-2,2-dimethylpropanoate

MK 0591 sodium; MK-0591; MK0591; L 686708; L-686,708; MK 591; MK591; QUIFLAPON SODIUM; 147030-01-1; MK591; Quiflapon (sodium); MK-591; Quiflapon Sodium [USAN]; MK-591 (sodium); MK 591; MK-591

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~50 mg/mL (~82.08 mM)
H2O : < 0.1 mg/mL

Solubility in Formulation 1: ≥ 2.75 mg/mL (4.51 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 27.5 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.75 mg/mL (4.51 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 27.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)