phospholipase a-2

BMS493 is an inverse agonist of the pan-retinoic acid receptor (RAR) that inhibits retinoic acid-induced differentiation, enhances the interaction of nuclear co-inhibitors with RARs, attenuates RA signaling, potentiates TPP-induced toxicity, and inhibits the increase in phospholipase A2 activity.

PACOCF3 (Palmityltrifluoromethylketone) (Palmityltrifluoromet hylketone) is an inhibitor of Ca(2+)-independent phospholipase A2(PLA2) with an IC 50 of 3.8 μM. PACOCF3 alters Ca 2+ signaling in renal tubular cells [1] [2].

Phospholipase A2 (PLA2) is an enzyme that hydrolyzes fatty acids present in the sn-2 position of phospholipids, and is closely related to lipid metabolism and immune function.

Rhamnetin (beta-Rhamnocitrin), a quercetin derivative found in Coriandrum sativum, has antioxidant and anti-inflammatory activities. Rhamnetin inhibits secretory phospholipase A2.

Triamcinolone (Aristocort) is a synthetic glucocorticoid with anti-inflammatory and immunomodulating properties. Upon cell entry, triamcinolone binds to and activates the glucocorticoid receptor, which leads to translocation of the ligand-receptor complex to the nucleus and induces expression of glucocorticoid-responsive genes such as lipocortins. Lipocortins inhibit phospholipase A2, thereby blocking the release of arachidonic acid from membrane phospholipids and preventing the synthesis of prostaglandins and leukotrienes, both mediators of inflammation. In addition, pro-inflammatory cytokine production, including interleukin (IL)-1and IL-6, and the activation of cytotoxic T-lymphocytes is also inhibited. T-cells are prevented from making IL-2 and proliferating. This agent also decreases the number of circulating lymphocytes, induces cell differentiation, and stimulates apoptosis through increasing Ikappa-B expression and curtailing activation of nuclear factor (NF)kappa-B.

3-Nitrocoumarin (3-nitrochromen-2-one) (3-NC) is a potent and selective Phospholipase C-γ (PLCγ) inhibitor.

Lp-PLA2-IN-2 is a selective and potent lipoprotein-associated phospholipase A2 (Lp-PLA2) inhibitor, with an IC50 of 120 nM for recombinant human Lp-PLA2.

2-(E-2-decenoylamino)ethyl 2-(cyclohexylethyl) sulfide inhibits stress-induced ulcers by maintaining phospholipase A2 and prostaglandin E2 levels in rats subjected to water immersion-restrained stress-induced ulceration.

2-Methylbutyrylcarnitine (chloride) acts as a gut microbial metabolite that targets integrin α2β1 on platelets, facilitating the activation of cytosolic phospholipase A2 (cPLA2) and enhancing platelet hyperresponsiveness. This compound further augments platelet hyperreactivity and promotes thrombus formation in mice. It is also characterized as a branched-chain acylcarnitine.

GK241 (compound 31a-c), a 2-oxoamide-based compound, exhibits inhibitory activity against group IIA secretory phospholipase A2 (GIIA sPLA2) in humans and mice, with IC50 values of 143 nM and 68 nM, respectively. The mechanism of inhibition has been explored through molecular dynamics simulations.

OBAA is a potent inhibitor of phospholipase A2 (PLA2) with an IC 50 of 70 nM. OBAA blocks Melittin-induced Ca 2+ influx in Trypanosoma brucei with an IC 50 of 0.4 μM [1] [2] [3].

Abroquinone A, a natural isoflavanquinone, has been shown to block cytosolic phospholipase A(2) and 5-lipoxygenase activation in neutrophils, it may have pharmaceutical potential as an antiallergic agent.

Amentoflavone (3',8''-Biapigenin), as a potent inhibitor of CYP3A4 and CYP2C9, can interact with many other medications. CYP3A4 and CYP2C9 are proteins used for drug metabolism in the body. Amentoflavone also is an inhibitor of human cathepsin B. It has antimalarial activity in trials significant affinities towards the Delta-1, kappa opioid receptors (as an antagonist) and binds to benzodiazepine receptors. Amentoflavone may be a potential lead for a new type of anti-inflammatory agents having the dual inhibitory activity of group II phospholipase A2 and cyclooxygenase. Amentoflavone and quercetin differentially exerted suppression of PGE2 biosynthesis via downregulation of COX-2/iNOS expression.

12-HETE ((±)12-HETE) is a modulator of PGE2, with both anti-thrombotic and pro-thrombotic effects, inducing PGE2 release and COX-2 expression via phospholipase A2 (sPLA2-IIA) inducers. It is also a neuroregulator activating retinal cell endothelial dysfunction in diabetic retinopathy.

PGBx is a mixture of oligomers of PGB1 with a molecular weight of 1,000-1,500. It has antioxidant and free radical trapping activity that was first studied in isolated mitochondria.1 PGBx has anti-inflammatory and cytoprotective activity which may be attributed to inhibition of the 14 kDa sPLA2.2,3 At a dose of 1 mg/kg, PGBx significantly reduces the incidence of ulcers in rats.2References1. Polis, B.D., Polis, E., and Kwong, S. Protection and reactivation of oxidative phosphorylation in mitochondria by a stable free-radical prostaglandin polymer (PGBΧ). Proceedings of the National Academy of Sciences of the United States of America 76, 1598-1602 (1979).2. Kumashiro, R., Devlin, T.M., Kholoussy, A.M., et al. Prostaglandin BΧ in the prevention of stress ulcers in rats. International Surgery 70, 247-250 (1985).3. Franson, R.C., Rosenthal, M.D., and Regelson, W. Mechanism(s) of cytoprotective and anti-inflammatory activity of PGB1 oligomers: PGBx has potent anti-phospholipase A2 and anti-oxidant activity. Prostaglandins, Leukotrienes and Essential Fatty Acids 43, 63-70 (1991). PGBx is a mixture of oligomers of PGB1 with a molecular weight of 1,000-1,500. It has antioxidant and free radical trapping activity that was first studied in isolated mitochondria.1 PGBx has anti-inflammatory and cytoprotective activity which may be attributed to inhibition of the 14 kDa sPLA2.2,3 At a dose of 1 mg/kg, PGBx significantly reduces the incidence of ulcers in rats.2 References1. Polis, B.D., Polis, E., and Kwong, S. Protection and reactivation of oxidative phosphorylation in mitochondria by a stable free-radical prostaglandin polymer (PGBΧ). Proceedings of the National Academy of Sciences of the United States of America 76, 1598-1602 (1979).2. Kumashiro, R., Devlin, T.M., Kholoussy, A.M., et al. Prostaglandin BΧ in the prevention of stress ulcers in rats. International Surgery 70, 247-250 (1985).3. Franson, R.C., Rosenthal, M.D., and Regelson, W. Mechanism(s) of cytoprotective and anti-inflammatory activity of PGB1 oligomers: PGBx has potent anti-phospholipase A2 and anti-oxidant activity. Prostaglandins, Leukotrienes and Essential Fatty Acids 43, 63-70 (1991).

C2 Phytoceramide is a bioactive semisynthetic sphingolipid that inhibits formyl peptide-induced oxidant release (IC50 = 0.38 μM) in suspended polymorphonuclear cells. It increases COX-2 protein levels 15-fold through ERK signaling. It induces death of keratinocytes (20% viability) with an ED50 value of 30 μM, the same concentration at which 35% of cells in a TUNEL assay are apoptotic. C2 Phytoceramide also has antiproliferative effects in CHO cells, with greater than 80% cytotoxicity achieved at a concentration of 20 μM, and induces internucleosomal DNA fragmentation. In addition, it inhibits the activation of phospholipase D (PLD) mediated by muscarinic acetylcholine receptors in vitro.

The phosphatidylinositol (PtdIns) phosphates represent a small percentage of total membrane phospholipids. However, they play a critical role in the generation and transmission of cellular signals. PtdIns-(1,2-dioctanoyl) is a synthetic analog of natural phosphatidylinositol (PtdIns) containing C8:0 fatty acids at the sn-1 and sn-2 positions. The compound features the same inositol and diacyl glycerol (DAG) stereochemistry as that of the natural compound. The short fatty acid chains of this analog, compared to naturally-occurring PtdIns, gives it different physical properties including high solubility in aqueous media. PtdIns are phosphorylated to mono- (PtdIns-P; PIP), di- (PtdIns-P2; PIP2), and triphosphates (PtdIns-P3; PIP3). Hydrolysis of PtdIns-(4,5)-P2 by phosphoinositide (PI)-specific phospholipase C generates inositol triphosphate (IP3) and DAG which are key second messengers in an intricate biochemical signal transduction cascade.

The phosphatidylinositol (PtdIns) phosphates represent a small percentage of total membrane phospholipids. However, they play a critical role in the generation and transmission of cellular signals. PtdIns-(3,4,5)-P3, also known as PIP3, is resistant to cleavage by PI-specific phospholipase C (PLC). Thus, it is likely to function in signal transduction as a modulator in its own right, rather than as a source of inositol tetraphosphates. PIP3 can serve as an anchor for the binding of signal transduction proteins bearing pleckstrin homology (PH) domains. Protein binding to PIP3 is important for cytoskeletal rearrangement and membrane trafficking. PtdIns-(3,4,5)-P3 (1,2-dihexanoyl) is a synthetic analog of natural PIP3 with C6:0 fatty acids at the sn-1 and sn-2 positions. The compound features the same inositol and diacylglycerol (DAG) stereochemistry as that of the natural compound. The short fatty acid chains of this analog give it different physical properties from naturally-occurring PIP3, including higher solubility in aqueous media.

The phosphatidylinositol (PtdIns) phosphates represent a small percentage of total membrane phospholipids. However, they play a critical role in the generation and transmission of cellular signals. PtdIns-(4)-P1 (1,2-dioctanoyl) is a synthetic analog of natural phosphatidylinositol (PtdIns) featuring C8:0 fatty acids at the sn-1 and sn-2 positions. The compound contains the same inositol and diacylglycerol (DAG) stereochemistry as the natural compound. PtdIns-(4)-P1 can be phosphorylated to di- (PtdIns-P2; PIP2) and triphosphates (PtdIns-P3; PIP3). Hydrolysis of PtdIns-(4,5)-P2 by phosphoinositide (PI)-specific phospholipase C generates inositol triphosphate (IP3) and DAG which are key second messengers in an intricate biochemical signal transduction cascade.

Tetranactin is a macrotetrolide and a monovalent cation ionophore that has been found in S. aureus and has antibacterial, insecticidal, and mitogenic activities. It exhibits an equilibrium permeability ratio 1,000-fold greater for lithium than sodium or cesium ions accross bilayer membranes at low voltages. Tetranactin inhibits the growth of Gram-positive bacteria and C. miyabeanus and R. solani fungi when used at concentrations less than 0.9 μg/ml. Tetranactin (0.5-1.5 μg per insect) dose-dependently increases the mortality of adult C. chinensis weevils up to 100% and has mitogenic activity against T. telarius when sprayed onto plants with an LC50 value of 9.2 μg/ml. It reduces IL-1β- and cAMP-induced secretion of phospholipase A2 (PLA2) from rat mesangial cells (IC50s = 43 and 33 nM, respectively). Tetranactin (50 ng/ml) suppresses the proliferation of human T lymphocytes induced by allogeneic cells and IL-2 and supresses the generation of cytotoxic T lymphocytes in mixed lymphocyte cultures. In vivo, tetranactin (10 mg/animal per day) completely inhibits the formation of experimental autoimmune uveoretinitis (EAU) in rats.

Diheptanoyl Thio-PC is a substrate for all phospholipase A2s (PLA2s) with the exception of cPLA2 and PAF-acetyl hydrolase (PAF-AH). Interaction of this compound with a PLA2 results in cleavage of the sn-2 fatty acid generating a free thiol on the lysophospholipid. This free thiol can be detected using chromogenic substrates such as DTNB (Ellman's reagent) and DTP.

Phosphatidylcholine (PC) species are a common class of phospholipids that comprise the mammalian cell membrane. 1,2-Dioctanoyl PC is a synthetic analog of natural phosphatidylcholine species containing saturated C8:O fatty acids in the sn-1 and sn-2 positions of the glycerol backbone. It exhibits a critical micelle concentration (CMC) value of 0.25 mM at 27°C. 1,2-Dioctanoyl PC serves as an efficient substrate for phospholipase D (PLD) as well as sPLA2 isozymes from bovine pancreas and bee venom.

Thioester analogs of glycerophospholipids, in combination with Ellman's reagent, are convenient colorimetric substrates for the measurement of phospholipase (PL) activity. Palmitoyl thio-PC is a chromogenic PLA2 substrate that contains a palmitoyl thioester at the sn-2 position of the glycerol backbone. Hydrolysis of the thioester by PLA2 yields a free thiol that reacts readily with DTNB (Ellman's reagent) giving a bright yellow product with an absorbance maximum at 412 nm. Palmitoyl thio-PC has been used to measure bee venom sPLA2 activity in a phospholipid:Triton X-100 mixed micelle system.

Phospholipase A2 (PLA2) catalyzes the hydrolysis of phospholipids at the sn-2 position leading to the production of lysophospholipids and free fatty acids. Calcium-dependent cytosolic PLA2 (cPLA2α) is a 85 kDa enzyme that plays a key role in the arachidonic cascade and the inflammatory response associated with this metabolic pathway. CAY10502 is a potent inhibitor of calcium-dependent cytosolic PLA2α (cPLA2α) with an IC50 value of 4.3 nM for the purified enzyme from human platelets. It inhibits arachidonic acid mobilization from A23187-stimulated or TPA-stimulated human platelets with IC50 values of 570 and 0.9 nM, respectively.