D609

D609 is a specific and competitive inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC) with a Ki value of 6.4 μM. [1]

PC-PLC hydrolyzes (phosphatidylcholine) PC to generate 1, 2-diacylglycerol (DAG) and phosphocholine. D609 is a widely known inhibitor of PC-PLC and also inhibit sphingomyelin synthase (SMS). Due to these actions, it has antiviral and antitumor properties. D609 does not inhibit bacterial phosphatidylinositol (PI)-PLC, bovine pancreatic PLA2 or phospholipase D from cabbage[1b]. In OVCAR3 cells treated with (53 μg/mL) for 24 h, PC-PLC activity was significantly inhibited and cell proliferation was affected. In breast cancer cells, the activity of PC-PLC decreased 3.5 fold after the incubation with D609 (50 μg/ml) within 1h. The human epidermal growth factor receptor 2 (HER2) was also down-regulated [2]. D609 also has anti-inflammatory functions. It blocked the nitric oxide synthase induced by LPS (IC50=20 μg/mL) and IL-1β induced vascular cell adhesion molecule 1 gene expression in human endothelial cells.[3]

D609 can reduce sphingomyelin synthase, thereby it inhibits bFGF-stimulated astrocyte proliferation. Because of the presence of the thiol function, D609 also has antioxidant/glutathione mimetic properties[1b].

References:
1. a) E. Amtmann, Drugs Exp Clin Res 1996, 22, 287-294; b) R. M. Adibhatla, J. F. Hatcher and A. Gusain, Neurochem Res 2012, 37, 671-679.
2. L. Paris, S. Cecchetti, F. Spadaro, L. Abalsamo, L. Lugini, M. E. Pisanu, E. Iorio, P. G. Natali, C. Ramoni and F. Podo, Breast Cancer Res 2010, 12, R27.
3. a) K. Tschaikowsky, M. Meisner, F. Schonhuber and E. Rugheimer, Br J Pharmacol 1994, 113, 664-668; b) R. R. Cobb, K. A. Felts, G. C. Parry and N. Mackman, Mol Pharmacol 1996, 49, 998-1004. >

Cell lipid metabolism modulators 2-bromopalmitate, D609, monensin, U18666A and probucol shift discoidal HDL formation to the smaller-sized particles: implications for the mechanism of HDL assembly.[Pubmed:27671775]

Biochim Biophys Acta. 2016 Dec;1861(12 Pt A):1968-1979.

ATP-binding cassette transporter A1 (ABCA1) mediates formation of disc-shaped high-density lipoprotein (HDL) from cell lipid and lipid-free apolipoprotein A-I (apo A-I). Discoidal HDL particles are heterogeneous in physicochemical characteristics for reasons that are understood incompletely. Discoidal lipoprotein particles similar in characteristics and heterogeneity to cell-formed discoidal HDL can be reconstituted from purified lipids and apo A-I by cell-free, physicochemical methods. The heterogeneity of reconstituted HDL (rHDL) is sensitive to the lipid composition of the starting lipid/apo A-I mixture. To determine whether the heterogeneity of cell-formed HDL is similarly sensitive to changes in cell lipids, we investigated four compounds that have well-established effects on cell lipid metabolism and ABCA1-mediated cell cholesterol efflux. 2-Bromopalmitate, D609, monensin and U18666A decreased formation of the larger-sized, but dramatically increased formation of the smaller-sized HDL. 2-Bromopalmitate did not appear to affect ABCA1 activity, subcellular localization or oligomerization, but induced dissolution of the cholesterol-phospholipid complexes in the plasma membrane. Arachidonic and linoleic acids shifted HDL formation to the smaller-sized species. Tangier disease mutations and inhibitors of ABCA1 activity wheat germ agglutinin and AG 490 reduced formation of both larger-sized and smaller-sized HDL. The effect of probucol was similar to the effect of 2-bromopalmitate. Taking rHDL formation as a paradigm, we propose that ABCA1 mutations and activity inhibitors reduce the amount of cell lipid available for HDL formation, and the compounds in the 2-bromopalmitate group and the polyunsaturated fatty acids change cell lipid composition from one that favors formation of the larger-sized HDL particles to one that favors formation of the smaller-sized species.

D609-mediated inhibition of ATP synthesis in neural progenitor cells.[Pubmed:24918458]

Neuroreport. 2014 Jul 9;25(10):777-81.

Tricyclodecan-9-yl-xanthogenate (D609) is an antioxidative molecule with antiproliferative and neuroprotective properties in a variety of cells. Previously, we have shown that D609 decreased the proliferation of neural progenitor cells. In this study, we examined the antioxidative property of D609 on neural progenitor cells isolated from the subventricular zone of the rat brain. Cellular oxidation was assessed by measuring the ATP content of the cells. Our results show that D609 decreased the ATP content of the neural progenitor cells by approximately 40%, suggesting the possible inhibition of cellular metabolic activity. Cytochrome c oxidase (Cox), also known as complex IV of the electron transport chain, is a terminal enzyme involved in the oxidation of substrates resulting in the generation of energy required for the cellular activity. Therefore, regulating the activity of Cox could interfere with the generation of ATP, consequently affecting the proliferation of cells. Consistent with this hypothesis, we also observed a decrease in the Cox activity following the incubation of neural progenitor cells with D609. These results suggest that D609 could inhibit the activity of Cox and subsequent ATP synthesis in the neural progenitor cells.

Effect of D609 on the expression of GADD45beta protein: Potential inhibitory role in the growth of glioblastoma cancer stem like cells.[Pubmed:27658347]

Eur J Pharmacol. 2016 Nov 15;791:510-517.

GADD45beta (Growth Arrest and DNA Damage inducible protein) is a stress activated protein which plays an important role in regulating apoptosis, proliferation, DNA repair and potentially may have a role in cancer. In this study we examined the role of anti-oxidative stress on the expression of GADD45beta in glioma stem-like cells (GSC). We show that patient derived GSCs have high survival in the absence of exogenous growth factors. Addition of D609 (Tricyclodecan-9-yl-xanthogenate), a known anti-oxidative compound, to GSCs reduced the cellular ATP content with significant effects observed when GSCs were cultured in growth factor free medium. D609 exposure also resulted in a decrease in the protein and an increase in mRNA of GADD45beta with a concomitant decline in the survival of cells. However, under similar conditions the phosphorylation of p38 MAP kinase (stress activated MAP kinase), a downstream target of GADD45beta, was significantly enhanced in response to D609. Therefore it appears that GADD45beta might play a role in glioma stem cell survival and that p38 MAP kinase may not be directly activated by GADD45beta. Together these observations suggest that anti-oxidative compounds like D609 can target GADD45beta which may be one strategy to curtail the growth of glioma stem like cells.

What Is the True Structure of D609, a Widely Used Lipid Related Enzyme Inhibitor?[Pubmed:26854352]

Org Lett. 2016 Feb 19;18(4):768-71.

D609 (1) has been used as a lipid-related enzyme inhibitor during the past three decades. Although it has eight possible stereoisomers, no systematic research considering its chirality has been performed. In this paper, eight possible chiral alcohols as direct precursors of D609 were synthesized, and their stereochemistries were elucidated by a vibrational circular dichroism (VCD) technique. Phosphatidylcholine-specific phospholipase C and sphingomyelin synthase inhibition assays of these isomers showed considerable differences in their activities.

D609 inhibits ionizing radiation-induced oxidative damage by acting as a potent antioxidant.[Pubmed:11408530]

J Pharmacol Exp Ther. 2001 Jul;298(1):103-9.

Tricyclodecan-9-yl-xanthogenate (D609) has been extensively studied in biological systems and exhibits a variety of biological functions, including antiviral, antitumor, and anti-inflammatory activities. Most of these activities have been largely attributed to the inhibitory effect of D609 on phosphatidylcholine-specific phospholipase C. However, as a xanthate derivative, D609 is a strong electrolyte and readily dissociates to xanthate anions and cations of alkali metals in solution. Xanthate anions and protonated xanthic acid contain a free thiol moiety and are highly reductive. This implies that D609 and other xanthate derivatives may function as potent antioxidants. Indeed, we found that D609 inhibited the Fenton reaction-induced oxidation of dihydrorhodamine 123 in a dose-dependent manner similar to that of pyrrolidinedithiocarbamate, a well known antioxidant. In addition, D609 inhibited the formation of the alpha-phenyl-tert-butylnitrone-free radical spin adducts and lipid peroxidation of synaptosomal membranes by the Fenton reagents. Furthermore, preincubation of lymphocytes with D609 resulted in a significant diminution of ionizing radiation (IR)-induced 1) production of reactive oxygen species; 2) decrease in intracellular reduced glutathione; 3) oxidative damage to proteins and lipids; and 4) activation of nuclear factor-kappaB. Moreover, when D609 (50 mg/kg i.v.) was administered to mice 10 min prior to total body IR (6.5 and 8.5 Gy), it protected the mice from IR-induced lethality. Thus, these results indicate that D609 is a potent antioxidant and has the ability to inhibit IR-induced cellular oxidative stress.

Phosphatidylcholine-specific phospholipase C regulates glutamate-induced nerve cell death.[Pubmed:9636222]

Proc Natl Acad Sci U S A. 1998 Jun 23;95(13):7748-53.

Phosphatidylcholine-specific phospholipase C (PC-PLC) is a necessary intermediate in transducing apoptotic signals for tumor necrosis factor and Fas/Apo-1 ligands in nonneuronal cells. The data presented here show that PC-PLC also is required in oxidative glutamate-induced programmed cell death of both immature cortical neurons and a hippocampal nerve cell line, HT22. In oxidative glutamate toxicity, which is distinct from excitotoxicity, glutamate interferes with cystine uptake by blocking the cystine/glutamate antiporter, indirectly causing a depletion of intracellular glutathione. A PC-PLC inhibitor blocks oxidative glutamate toxicity, and exogenous PC-PLC potentiates glutamate toxicity. The inhibition of PC-PLC uncouples the cystine uptake from glutamate inhibition, allowing the maintenance of glutathione synthesis and cell viability. These data suggest that PC-PLC modulates neuronal cell death through a mechanism that is distinct from that involved in nonneuronal apoptosis.

The antiviral, antitumoural xanthate D609 is a competitive inhibitor of phosphatidylcholine-specific phospholipase C.[Pubmed:9034754]

Drugs Exp Clin Res. 1996;22(6):287-94.

The effect of the antiviral, antitumoural xanthate D609 on the activity of phospholipase A2, C (PC- and Pi-specific) and D was investigated. D609 is the first model substance of a new concept of antiviral therapy that interferes with cellular regulation mechanisms, rather than with virus coded enzymes. Exclusively phosphatidylcholine (PC) specific phospholipase C (PC-PLC) was found to be inhibited in a dose-dependent manner. Enzyme activity was determined either as the rate of acid release from PC or as the rate of phosphorylcholine production form 3H labelled PC. Lineweaver-Burk plots revealed D609 as a competitive inhibitor of PC-PLC with a Ki of 6.4 microM. In addition, D609 competitively inhibited PC-PLC mediated cleavage of P-nitrophenylphosphorylcholine (p-NPP), a pseudo-substrate of PC-PLC with a Ki of 8.8 microM. These data suggest that D609 competes with the phosphorylcholine residue of PC for binding to PC-PLC.

Induction of nitric oxide synthase activity in phagocytic cells inhibited by tricyclodecan-9-yl-xanthogenate (D609).[Pubmed:7532078]

Br J Pharmacol. 1994 Nov;113(3):664-8.

1. The synthesis of nitric oxide (NO) by immune-stimulated murine phagocytic cells (J774) and the modulation of this synthesis by tricyclodecan-9-yl-xanthogenate (D609), a specific inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), was investigated. D609 dose-dependently suppressed production of NO, as measured by the release of nitrite and nitrate, in response to lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) in intact cultured cells with an IC50 of approximately 20 micrograms ml-1. D609 at 40 micrograms ml-1 completely abrogated immune-stimulated nitrite production. 2. The inhibitory effects of D609 on nitrite production were time-dependent and restricted to the first 18 h post-stimulation. D609 did not inhibit nitrite production in the cytosol of immune-stimulated phagocytes. 3. These findings indicate that the xanthogenate, D609, is a potent inhibitor of the induction of NO-synthase activity in immune-stimulated phagocytes. Furthermore, since D609 has been demonstrated to inhibit PC-PLC specifically, our findings suggest that the activation of this enzyme by LPS and IFN-gamma is a proximal step in the signal transduction of inducible NO-synthase in phagocytic cells.