991 resultados para HepG2 cell


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Epidemiological studies have provided evidence that high consumption of tomatoes effectively reduces the risk of reactive oxygen species (ROS)-mediated diseases such as cancer. Tomatoes are rich sources of lycopene, a potent singlet oxygen-quenching carotenoid. In addition to its antioxidant properties, lycopene shows an array of biological effects including antimutagenic and anticarcinogenic activities. In the present study, the chemopreventive action of lycopene was examined on DNA damage and clastogenic or aneugenic effects of H2O2 and n-nitrosodiethylamine (DEN) in the metabolically competent human hepatoma cell line (HepG2 cells). Lycopene at concentrations of 10. 25, and 50 mu M, was tested under three protocols: before, simultaneously, and after treatment with the mutagen, using the comet and micronucleus assays. Lycopene significantly reduced the genotoxicity and mutagenicity of H2O2 in all of the conditions tested. For DEN, significant reductions of primary DNA damage (comet assay) were detected when the carotenoid (all of the doses) was added in the cell culture medium before or simultaneously with the mutagen. In the micronucleus test, the protective effect of lycopene was observed only when added prior to DEN treatment. In conclusion, our results suggest that lycopene is a suitable agent for preventing chemically-induced DNA and chromosome damage. (C) 2007 Elsevier Ltd. All rights reserved.

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Reports show that cold atmospheric-pressure plasmas can induce death of cancer cells in several minutes. However, very little is presently known about the mechanism of the plasma-induced death of cancer cells. In this paper, an atmospheric-pressure plasma plume is used to treat HepG2 cells. The experimental results show that the plasma can effectively control the intracellular concentrations of ROS, NO and lipid peroxide. It is shown that these concentrations are directly related to the mechanism of the HepG2 death, which involves several stages. First, the plasma generates NO species, which increases the NO concentration in the extracellular medium. Second, the intracellular NO concentration is increased due to the NO diffusion from the medium. Third, an increase in the intracellular NO concentration leads to the increase of the intracellular ROS concentration. Fourth, the increased oxidative stress results in more effective lipid peroxidation and consequently, cell injury. The combined action of NO, ROS and lipid peroxide species eventually results in the HepG2 cell death. The mechanism of death of human hepatocellular carcinoma cells (HepG2) induced by atmospheric-pressure room-temperature plasma, related to the plasma-controlled intracellular concentrations of reactive oxygen species (ROS), nitric oxide (NO) and lipid peroxide is revealed. Only 34.75 s are required to reduce the number of the viable HepG2 cells by 50%.

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Oxysterols are products of cholesterol oxidation, which may be produced endogenously or may be absorbed from the diet where they are commonly found in foods of animal origin. Oxysterols are known to be cyctotoxic to cells in culture and mode of toxicity has been identified as apoptosis in certain cell lines. The cytotoxicity of the oxysterols 25-hydroxycholesterol (25-OH) and 7β-hydroxycholesterol (7β-OH) was examined in two human cell lines, HepG2, a hepatoma cell line, and U937, a monocytic cell line. Both 25-OH and 7β-OH were cytotoxic to the HepG2 cell line but apoptotic cells were not detected and it was concluded that cells underwent necrosis. 25-OH was not cytotoxic to the U937 cell line but it was found to have a cytostatic effect. 7β-OH was shown to induce apoptosis in the U937 line. The mechanism of oxysterol-induced apoptosis has not yet been fully elucidated, however the generation of an oxidative stress and the depletion of glutathione have been associated with the initial stages of the apoptotic process. The concentration of cellular antioxidant enzyme, superoxide dismutase (SOD) was increased in association with 7β-OH induced apoptosis in the U937 cell line. There was no change in the glutathione concentration or the SOD activity of HepG2 cells, which underwent necrosis in the presence of 7β-OH. Many apoptotic pathways center on the activation of caspase-3, which is the key executioner protease of apoptosis. Caspase-3 activity was also shown to increase in association with 7β-OH-induced apoptosis in U937 cells but there was no significant increase in caspase-3 activity in HepG2 cells. DNA fragmentation is regarded as the biochemical hallmark of apoptosis, therefore the comet assay as a measure of DNA fragmentation was assessed as a measure of apoptosis. The level of DNA fragmentation induced by 7β-OH, as measured using the comet assay, was similar for both cell lines. Therefore, it was concluded that the comet assay could not be used to distinguish between 7β-OH-induced apoptosis in U937 cells and 7β-OH-induced necrosis in HepG2 cells. The cytotoxicity and apoptotic potency of oxysterols 25-OH, 7β-OH, cholesterol- 5a,6a-epoxide (a-epoxide), cholesterol-5β,6β-epoxide (β-epoxide), 19-hydroxy-cholesterol (19-OH), and 7-ketocholesterol (7-keto) was compared in the U937 cell line. 7 β-OH, β-epoxide and 7-keto were found to induce apoptosis in U937 cells. 7β-OH-induced apoptosis was associated with a decrease in the cellular glutathione concentration and an increase in SOD activity, 7-keto and β-epoxide did not affect the glutathione concentration or the SOD activity of the cells.a-Epoxide, 19-OH and 25-OH were not cytotoxic to the U937 cell line.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Several epidemiological and experimental studies has been reported that lutein (LT) presents antioxidant properties. Aim of the present study was to investigate the protective effects of LT against oxidative stress and DNA damage induced by cisplatin (cDDP) in a human derived liver cell line (HepG2). Cell viability and DNA-damage was monitored by MU and comet assays. Moreover, different biochemical parameters related to redox status (glutathione, cytochrome-c and intracellular ROS) were also evaluated. A clear DNA-damage was seen with cDDP (1.0 mu M) treatment. In combination with the carotenoid, reduction of DNA damage was observed after pre- and simultaneous treatment of the cells, but not when the carotenoid was added to the cells after the exposure to cDDP. Exposure of the cells to cDDP also caused significant changes of all biochemical parameters and in co-treatment of the cells with LT, the carotenoid reverted these alterations. The results indicate that cDDP induces pronounced oxidative stress in HepG2 cells that is related to DNA damage and that the supplementation with the antioxidant LT may protect these adverse effects caused by the exposure of the cells to platinum compound, which can be a good predict for chemoprevention. (C) 2011 Elsevier Ltd. All rights reserved.

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New complexes, [Ni(HL)(PPh3)]Cl (1), [Pd(L)(PPh3)](2), and [Pd(L)(AsPh3)](3), were synthesized from the reactions of 4-chloro-5-methyl-salicylaldehyde thiosemicarbazone [H2L] with [NiCl2(PPh3)(2)], [PdCl2(PPh3)(2)] and [PdCl2(AsPh3)(2)]. They were characterized by IR, electronic, H-1-NMR spectral data. Further, the structures of the complexes have been determined by single crystal X-ray diffraction. While the thiosemicarbazone coordinated as binegative tridentate (ONS) in complexes 2 and 3, it is coordinated as mono negative tridentate (ONS) in 1. The interactions of the new complexes with calf thymus DNA was examined by absorption and emission spectra, and viscosity measurements. Moreover, the antioxidant properties of the new complexes have also been tested against DPPH radical in which complex 1 exhibited better activity than that of the other two complexes 2 and 3. The in vitro cytotoxicity of complexes 1-3 against A549 and HepG2 cell lines was assayed, and the new complexes exhibited higher cytotoxic activity with lower IC50 values indicating their efficiency in killing the cancer cells even at very low concentrations.

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Four dinucleating bis(thiosemicarbazone) ligands and their zinc complexes have been synthesized and characterized by multinuclear NMR (H-1 and C-13), IR, UV-Vis, ESI-MS and fluorescence spectroscopic techniques. Their purity was assessed by elemental analysis. Cytotoxicity was tested against five human cancer cell lines using the sulphorhodamine B (SRB) assay, where one of the complexes, 1,3-bis{biacetyl-2'-(4 `'-N-pyrrolidinylthiosemicarbazone)-3'-(4 `'-N-pyrrolidinylthiosemicarbazone) zinc(II)} propane (6), was found to be quite cytotoxic against MCF-7 (breast cancer) and HepG2 (hepatoma cancer) cell lines, with a potency similar to that of the well known anticancer drug adriamycin. It is evident from the cellular uptake studies that the uptake is same for the active complex 6 and the inactive complex 8 (1,6-bis{biacetyl- 2'-(4 `'-N-pyrrolidinylthiosemicarbazone)-3'-(4 `'-N-pyrrolidinylthiosemicarbazone) zinc(II)} hexane) in MCF-7 and HepG2 cell lines. In vitro DNA binding and cleavage studies revealed that all complexes bind with DNA through electrostatic interaction, and cause no significant cleavage of DNA. (C) 2'13 Elsevier B. V. All rights reserved.

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对Egonol龙胆三糖苷及以Egonol衍生物对雌二醇生成活性及其相关机制进行了研究。发现Egonol龙胆三糖苷促雌二醇最高生成率在MCF-7、HepG2、ROS1728中分别为157% 、182.4%、226.8%(以空白组200μg/ml睾酮转换成E2值作为100%生成率)。活性的强弱可能与芳香化酶的组织特异性表达情况一致,说明Egonol龙胆三糖苷促雌二醇活性可能与芳香化酶有关。芳香化酶的组织特异性表达与特异性启动子有关系,Egonol龙胆三糖苷在各组织中皆有促雌二醇活性,说明该化合物不是通过调节该酶的基因表达而起作用。 在探究Egonol龙胆三糖苷及其衍生物是否介导cAMP-PKA途径从而影响芳香化酶的表达中,发现该系列化合物在HEK-293T细胞中对cAMP的影响非常弱小。在人HepG2细胞中显示了极强的提高cAMP的作用。而化合物对cAMP的作用与其促雌二醇活性强弱不呈正相关关系,对c AMP-PKA途径的激活可能与胞内雌激素有关。 Egonol龙胆三糖苷及其衍生物对HepG2细胞增殖影响显示,该系列化合物同雌二醇一样有相似的较弱促HepG2细胞增殖作用。而且存在一定剂量依赖性。在瞬时转染有ERE(雌激素作用元件)的HepG2中,Egonol龙胆三糖苷及其衍生物也显示了类似于雌二醇与ERE结合的作用,进一步提示Egonol龙胆三糖苷及其衍生物在HepG2细胞中具备雌激素样作用。 为研究Egonol龙胆三糖苷及其衍生物是否可能直接提高芳香化酶的活性,我们计划将芳香化酶从芳香化酶阳性细胞中克隆后表达到芳香化酶阴性的细胞中。在MCF-7细胞中以Oligo dT为引物合成的cDNA模板,和在ROS1728细胞中以Oligo dT及大鼠引物F链为引物合成的cDNA模板能成功扩增出与芳香化酶全长编码序列大小一致的片段。 Egonol衍生物在HepG2、ROS1728细胞中促雌二醇活性的实验表明,Egonol苯环上引入其它基团可以提高Egonol的活性。 从雌激素经典的基因组效应和非基因组效应两方面对雌激素信号转导研究进展进行了简单的综述。 The promoting effects of egonol gentiotrioside and egonol derivatives on the synthesis of estrogen E2 were studied. In vitro test, egonol gentiotrioside promoted the synthesis of estrogen E2 in MCF-7, HepG2,ROS1728 cell lines with mean yields of estrogen E2 57%,82.4% and 126.8%, higher than those of blank control at a concentration of 100 mg/ml. The difference of estrogen E2 synthesis promoting effects among the cell lines suggested tissue specificity. It is in accordance with tissue specific character of aromatase expression. The evidence implied that effect of egonol gentiotrioside on promoting the synthesis of estrogen E2 was related to the aromatase. Different expression levels of aromatase in different tissues are attributed to their specific promoters, but egonol gentiotrioside can promote the synthesis of estrogen E2, in many tissues,so the fact is controversary to the estimation that this compound regulates the aromatase on gene level. In order to investigate whether egonol gentiotrioside and its synthetic derivatives regulates aromatase activity through the cAMP-PKA signal pathway,we transfected the p CRE-Luc luciferase reporter gene into the HEK-293T cells and HepG2 cells. These compounds had weak activity in promoting the cAMP activity in HEK-293T cells but strong in HepG2 cells.The compounds’effect of promoting the cAMP may be related to their estrogenic activity in cells. The modified HepG2 cell proliferation assay was used to evaluate the estrogenic activity of egonol gentiotrioside and its derivatives. The weak estrogenic activity of egonol gentiotrioside and its derivatives at various concentrations expressed as proliferative effect relative to that of blank control was examined. We transfected the pERE-Luc luciferase reporter gene into the HepG2 cells. These compounds possessed significant activity on estrogen response element compared with the one treated with 10 n M estrogen E2. This evidence indicated that the estrogenic activity of egonol gentiotrioside and its derivatives. In order to investigate whether the egonol gentiotrioside and its derivatives can upregulate the activity of aromatase directly, The full-length of P450 aromatase cDNA encoding aromatase were amplified by using primer Oligo dT in MCF-7,and specific primer in ROS1728,respectively. The structure-activity relationship of Egonol in promoting the synthesis of E2 in HepG2 and ROS1728 cells indicated that introduction of some group on the basic sketon of egonol could improve the effect. The progress in research of signal pathway of estrogen in recent years was summarized.

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本论文对滇金足草(Goldfussia yunnanensis)、凋缨菊(Camchaya loloana)和长喙吴萸(Evodia vestia)的化学成分进行了研究,通过色谱分离得到40个化合物。主要基于波谱数据鉴定了它们的结构,其中10个为新化合物。 1.从滇金足草地上枝叶的95%乙醇提取物中共分离鉴定了16个化合物:泽漆内酯A(1)、18-羟基泽漆内酯A(2)、18-氧代泽漆内酯A(3)、18-羟基-3-O-β-D-吡喃葡萄糖-泽漆内酯A(4)、3-O-β-D-吡喃葡萄糖-泽漆内酯A(5)、3-O-β-D-吡喃半乳糖-泽漆内酯A(6)、6-E-肉桂酰哈巴俄苷(7)、E-哈巴俄苷(8)、5,6-异亚丙二氧基哈巴俄苷(9)、β-谷甾醇(10)、β-胡萝卜苷(11)、齐墩果酸(12)、肉桂酸(13)、麦角固醇(14)、硬脂酸(15)和丁二酸(16)。其中2-7为新化合物。5,6-异亚丙二氧基哈巴俄苷(9)以人工产物形式得到。 2.从凋缨菊地上枝叶的95%乙醇提取物中分离并鉴定了13个化合物:凋缨菊内酯A~C (17-19)、1β-乙酰基凋缨菊内酯C(20)、b-谷甾醇(10)、β-胡萝卜苷(11)、羽扇豆醇(21)、桦木醇(22)、桦木酸(23)、芥子醇(24)、紫丁香苷(25)、咖啡酸(26)和熊果酸(27)。其中化合物17-20为桉叶烷内酯类新化合物。化合物17、18、20对细胞株HepG2的GI50依次为7.80、7.08、4.99 µg/mL。 3.从长喙吴萸(E. vestia)地上枝叶的95%乙醇提取物中分离并鉴定了13个化合物:佛手内酯(28)、花椒毒素(29)、异茴芹内酯(30)、七叶内酯(31)、东莨宕素(32)、瑞香素(33)、异紫花前胡内酯(34)、茵芋碱(35)、山刈碱(36)、白鲜碱(37)、黄柏酮(38)、柠檬苦素(39)和对羟基苯甲醛(40)。 4.综述了1990—2007年期间从菊科植物中发现的桉叶烷-12,6内酯的化学结构、生物活性、生物转化及化学合成方面的研究进展。 Phytochemical investigation on Goldfussia yunnanensis, Camchaya loloana, and Evodia vestia, led to the isolation of 40 compounds, 10 of which were new ones. 1. Six new compounds were isolation from 95% ethanolic extract of the aerial parts of G. yunnanensis, and identified as 18-hydroxyhelioscopinolide A (2), 18-oxohelioscopinolide A (3), 18-hydroxy-3-O-β-D-glucopyranosylhelioscopinolide A (4), 3-O-β-D-glucopyranosylhelioscopinolide A (5),3-O-β-D-Galactopyranosyl helioscopinolide A (6), 6-O-trans-cinnamoyl E-harpagoside (7). The known compounds isolated were helioscopinolide A (1), E-harpagoside A (8), 5,6-isopropylidene E-harpagoside A (9), β-sitosterol (10), β-daucosterol (11), oleanolic acid (12), cinnamic acid (13), ergosterol (14), stearic acid (15) and succinic acid (16). Compound 9 was an artifact. 2. Four new compounds, loloanolides A – C (17 - 19) and 1β-acetoxy-loloanolide C (20), were isolation from 95% ethanolic extract of the aerial parts of C. loloana. The known ones were β-sitosterol (10), β-daucosterol (11), lupeol (21), betulin (22), betulinic acid (23), sinapyl (24), syringin (25), caffeic acid (26) and ursolic acid (27). The GI50 values of compounds 17, 18 and 20 to HepG2 cell line were 7.80, 7.08 and 4.99 µg/mL, respectively. 3. Thirteen were isolated from 95% ethanolic extract of the aerial parts of E. vestia for the first time. They were determined to be bergapten (28), xanthotoxin (29), isopimpinellin (30), esculetin (31), scopoletin (32), daphnetin (33), marmesin (34), skimmianine (35), confusameline (36), dictamine (37), obacunone (38), limonin (39) and p-hydroxy phenyl aldehyde (40). 4. The structures, biological activities, biotransformation and chemical syntheses of eudesmane-12, 6-olides from the Asteraceae during 1990-2007 were reviewed.

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Elevated plasma concentrations of lipoprotein(a) [Lp(a)] have been identified as an independent risk factor for vascular diseases including coronary heart disease and stroke. In the current study, we have examined the binding and degradation of recombinant forms of apolipoprotein(a) [r-apo(a)], the unique kringle-containing moiety of Lp(a), using a cultured cell model. We found that the incubation of human hepatoma (HepG2) cells with an iodinated 17 kringle-containing (17K) recombinant form of apo(a) resulted in a two-component binding system characterized by a high affinity (Kd = 12 nM), low capacity binding site, and a low affinity (Kd = 249 nM), high capacity binding site. We subsequently determined that the high affinity binding site on HepG2 cells corresponds to the LDL receptor. In the HepG2 cell model, association of apo(a) with the LDL receptor was shown to be dependent on the formation of Lp(a) particles from endogenous LDL. Using an apo(a) mutant incapable of binding to the high affinity site through its inability to form Lp(a) particles (17KΔLBS7,8), we further demonstrated that the LDL receptor does not participate in Lp(a) catabolism. The low affinity binding component observed on HepG2 cells, familial hypercholesterolemia (FH) fibroblasts and human embryonic kidney (HEK) 293 cells may correspond to a member(s) of the plasminogen receptor family, as binding to this site(s) was decreased by the addition of the lysine analogue epsilon-aminocaproic acid. The lysine-dependent nature of the low affinity binding site was further confirmed in HepG2 binding studies utilizing r-apo(a) species with impaired lysine binding ability. We observed a reduction maximum binding capacity for 17K r-apo(a) variants lacking the strong lysine binding site (LBS) in kringle IV type 10 (17KΔAsp) and the very weak LBS in kringle V (17KΔV). Degradation of Lp(a)/apo(a) was found to be mediated exclusively by the low affinity component on both HepG2 cells and FH fibroblasts. Fluorescence confocal microscopy, using the 17K r-apo(a) variant fused to green fluorescent protein, further confirmed that degradation by the low affinity component on HepG2 cells does not proceed by the activity of cellular lysosomes. Taken together, these data suggest a potentially significant route for Lp(a)/apo(a) clearance in vivo.

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Alcohol binge drinking, especially in teenagers and young adults is a major public health issue in the UK, with the number of alcohol related liver disorders steadily increasing. Understanding the mechanisms behind liver disease arising from binge-drinking and finding ways to prevent such damage are currently important areas of research. In the present investigation the effect of acute ethanol administration on hepatic oxidative damage and apoptosis was examined using both an in vivo and in vitro approach; the effect of micronutrient supplementation prior and during ethanol exposure was also studied. The following studies were performed: (1) ethanol administration (75 mmol/kg body weight) and cyanamide pre-treatment followed by ethanol to study elevated acetaldehyde levels with liver tissue analysed 2.5, 6 and 24 hours post-alcohol; (2). Using juvenile animals, 2% betaine supplementation followed by acute ethanol with tissue analysed 24 hrs post ethanol; and (3). Micronutrient supplementation during concomitant ethanol exposure to hepG2 cells. It was found that a single dose of alcohol caused oxidative damage to the liver of rats at 2.5 hr post-alcohol as evidenced by decreased glutathione levels and increased malondialdehyde levels in both the cytosol and mitochondria. Liver function was also depressed but there were no findings of apoptosis as cytochrome c levels and caspase 3 activity was unchanged. At 6 hours, the effect of ethanol was reduced suggesting some degree of recovery, however, by 24 hours, increased mitochondrial oxidative stress was apparent. The effect of elevated acetaldehyde on hepatic damage was particularly evident at 24 hours, with some oxidative changes at earlier time points. At 24 hours, acetaldehyde caused a profound drop in glutathione levels in the cytosol and hepatic function was still deteriorating. Studies examining ethanol exposure to juvenile livers showed that glutathione levels were increased, suggesting an overtly protective response not seen in with older animals. It also showed that despite cytochrome c release into the cytosol, caspase-3 levels were not increased. This suggests that ATP depletion is preventing apoptosis initiation. Betaine supplementation prevented almost all of the alcohol-mediated changes, suggesting that the main mechanism behind alcohol-mediated liver damage is oxidative stress. Results using the hepG2 cell line model showed that micronutrients involved in glutathione synthesis can protect against hepatocyte damage caused by alcohol metabolism, with reduced reactive oxygen species and increased/maintained glutathione levels. In summary, these results demonstrate that both acute alcohol and acetaldehyde can have damaging effects to the liver, but that dietary intervention may be able to protect against ethanol induced oxidative stress.

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Studies indicate that several components were isolated from medicinal plants, which have antibacterial, antifungal, antitumor and anti-inflammatory properties. Sepsis is characterized by a systemic inflammation which leads to the production of inflammatory mediators exacerbated by excessive activation of inflammatory cells and disseminated intravascular coagulation (DIC), in which the human neutrophil elastase plays an important role in its pathogenesis. Several epidemiological studies suggest that components of plants, especially legumes, can play a beneficial role in reducing the incidence of different cancers. A chymotrypsin inhibitor of Kunitz (Varela, 2010) was purified from seeds of Erythrina velutina (Mulungu) by fractionation with ammonium sulfate, affinity chromatography on Trypsin-Sepharose, Chymotrypsin-Sepharose and ion exchange chromatography on Resource Q 1 ml (GE Healthcare) in system FPLC / AKTA. The inhibitor, called EvCI, had a molecular mass of 17 kDa determined by SDS-PAGE. The purified protein was able to inhibit human neutrophil elastase (HNE), with an IC50 of 3.12 nM. The EvCI was able to inhibit both pathways of HNE release stimulated by PAF and fMLP (75.6% and 65% respectively). The inhibitor also inhibited leukocyte migration in septic mice about 87% and prolonged the time of coagulation and inhibition factor Xa. EvCI showed neither hemolytic activity nor cytotoxicity. EvCI showed a selective antiproliferative effect to HepG2 cell lines with IC50 of 0.5 micrograms per milliliter. These results suggest EvCI as a molecule antagonist of PAF / fMLP and a potential use in fighting inflammation related disorders, disseminated intravascular coagulation (DIC) and cancer