Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “STILBENES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,387 records · Page 77Linked to original sources
PubMedDate not supplied

Multiple epoxide hydrolases in human lung.

Benzo(a)pyrene 4,5-oxide (BPO) hydrolase activity and trans-stilbene oxide hydrolase activity were measured in human lung samples obtained from 12 different patients. These activities, attributable to different epoxide hydrolases, were both found in significant amounts in the cytosolic as well as the microsomal cell fractions. The catalytic properties of human lung BPO hydrolases were further investigated, and similarities between the cytosolic and microsomal forms of this enzyme were noted. Similar Km values were found for both forms (22 microM for the microsomal enzyme, 37 microM for the cytosolic enzyme). Both forms responded in similar fashion to a number of enzyme inhibitors in vitro, and the IC50 values for each inhibitor were the same for both forms. Both forms of the enzyme were inhibited uncompetitively by trichloropropene oxide, and the Kii value for the cytosolic hydrolase (11 microM) was similar to that obtained for the microsomal hydrolase (15 microM). These two forms of BPO hydrolase in the human lung are very similar, possibly identical, enzymes.

Benzopyrenes↗
PubMed1985

Enzymatic hydration of leukotriene A4. Purification and characterization of a novel epoxide hydrolase from human erythrocytes.

Human erythrocytes contained a soluble cytosolic epoxide hydrolase for stereospecific enzymatic hydration of leukotriene A4 into leukotriene B4. The enzyme was purified 1100-fold, to apparent electrophoretic homogeneity, by conventional DEAE-Sephacel fractionation followed by high performance anion exchange and chromatofocusing procedures. Its characteristics include a molecular weight of 54,000 +/- 1,000, an isoelectric point 4.9 +/- 0.2, a Km apparent from 7 to 36 microM for enzymatic hydration of leukotriene A4, and a pH optimum ranging from 7 to 8. The enzyme was partially inactivated by its initial exposure to leukotriene A4. There was slow but detectable enzymatic hydration (pmol/min/mg) of certain arachidonic acid epoxides including (+/-)-14,15-oxido-5,8-11-eicosatrienoic acid and (+/-)-11,12-oxido-5,8,14-eicosatrienoic acid, but not others, including 5,6-oxido-8,11,14-eicosatrienoic acid. Human erythrocyte epoxide hydrolase did not hydrate either styrene oxide or trans-stilbene oxide. In terms of its physical properties and substrate preference for leukotriene A4, the erythrocyte enzyme differs from previously described versions of epoxide hydrolase. Human erythrocytes represent a novel source for an extrahepatic, cytosolic epoxide hydrolase with a potential physiological role.

8,11,14-Eicosatrienoic Acid↗
PubMed1988

The genetic variation and the expression of human glutathione transferase mu.

A glutathione transferase from human leukocytes (GT-tSBO) with high activity towards trans-stilbene oxide has now been found to correspond to the hepatic class Mu glutathione transferase. This class, Mu, of transferase(s) has been found in high concentration in liver, kidney, and adrenal gland, judged by he activity of GT-tSBO. This activity is only found in some individuals, approximately 46%. By using a cDNA clone derived from class Mu transferase(s) from mouse, it is suggested that this enzyme is not transcribed, depending on a deletion (of a part) of a gene in those individuals that are lacking the activity towards tSBO.

Chromosome Mapping↗
PubMed1977

Anion transport across the red blood cell membrane and the protein in band 3.

The paper reviews existing evidence for the participation of the protein in band 3 (nomenclature of Steck, [1]) in anion transport across the red cell membrane and discusses the possible role of common binding sites on band 3 for 1-fluoro-2,4-dinitrobenzene, 2-(4'-aminophenyl)-6-methylbenzenethiazol-3',7-disulfonic acid and dihydro 4,4'-diisothiocyanato stilbene-2,2'-disulfonic acid in the transport process.

Affinity Labels↗
PubMed1987

Studies on the ligand specificity and potential identity of microsomal antiestrogen-binding sites.

Synthetic nonsteroidal antiestrogens are bound intracellularly by two high affinity saturable bindings sites, the estrogen receptor and the microsomal antiestrogen-binding site (AEBS). In order to further define the structural requirements for ligand binding to AEBS from rat liver and the MCF 7 human breast cancer cell line, the relative binding affinities of an extensive series of structurally related ligands were investigated using competitive binding assay techniques. The groups of compounds studied were: analogues of the triphenylethylene antiestrogens, Cl 628 and tamoxifen; analogues of cyclofenil; bibenzyl and stilbene derivatives; analogues of the cytochrome P-450 inhibitor SKF-525A; phenothiazine derivatives; and a series of structurally related compounds with a variety of pharmacological activities. High affinity binding to AEBS required the presence of both a hydrophilic basic aminoether side chain and a hydrophobic aromatic ring structure (di- or tricyclic for maximal affinity). Structural modifications to either influenced binding affinity. Aromatic substitution either raised (CF3) or lowered (OH, OCH3) affinity, apparently by electronic effects transmitted through the benzene nucleus. Side chain structure was the major determinant of binding affinity, but its influence was complex and dependent upon terminal amino group structure, side chain branching and substitution, and tissue source of AEBS. Optimal binding affinity was shown by side chains bearing basic heterocyclic amino terminal groups. Other cellular sites that are known to bind antiestrogens with relatively high affinity include calmodulin, cytochrome P-450, and histamine, dopamine, and muscarinic receptors. Binding studies using a variety of pharmacologically active and radiolabeled ligands selective for these sites, including those for dopamine D1 and D2 receptors ([3H]fluphenazine, [3H]flupenthixol, [3H]spiperone, and [3H]SCH 23390) and histamine H1 receptors ([3H]pyrilamine), demonstrated that several of these compounds interact with AEBS with high affinity. However, the ligand specificity and other binding properties of the AEBS as determined by competitive binding studies and Scatchard analysis show this site to be a molecular entity truly distinct from these other cellular binding sites.

Animals↗
PubMed1986

Affinity chromatography of Band 3, the anion transport protein of erythrocyte membranes.

Affinity chromatography of Band 3 was performed using a series of affinity matrices synthesized with various inhibitor ligands and spacer arms. Hydrophilic spacer arms greater than four atoms in length were essential for Band 3 binding. An affinity resin prepared by reacting 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (Ki = 10 microM) with Affi-Gel 102 was found to be the most effective resin of the series tested. Solubilized proteins from human erythrocyte membranes were incubated with the affinity resin, and pure Band 3 was recovered by eluting with 4-benzamido-4'-aminostilbene-2,2'-disulfonate (BADS; Ki = 2 microM). Band 3 bound to the resin specifically in its stilbene disulfonate binding site, and optimal binding was achieved at pH 8 and at high ionic strength. At 4 degrees C, up to 80% of the bound Band 3 could be eluted by 1 mM BADS, whereas the remainder could be eluted under denaturing conditions using 1% lithium dodecyl sulfate. At 22 or 37 degrees C, the amount of BADS-elutable Band 3 was reduced with a concomitant increase of Band 3 in the lithium dodecyl sulfate elute. Thus, for successful affinity chromatography, the experiment must be carried out rapidly at 4 degrees C. This procedure was also used to purify the Band 3 protein from mouse, horse, pig, and chicken erythrocytes.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1975

Photochemical and biological degradation of water-soluble FWAs.

A study was made of the photochemical and biological degradation of two water-soluble fluorescent whitening agents (FWAs): the disodium 4,4'-bis(2-sulfostyryl)-biphenyl (1) and the disodium 4,4-bis ([4-anilino-6-(N-methyl-N-2-hydroxyethyl)amino 1,3,5-triazin-2-yl]amino)stilbene-2,2'-disulfonate (2). Each represents an important class of detergent fluorescent whitening agents. The photochemical degradation of (1) was studied by irradiating diluted aqueous solutions of this compound with a low intensity high pressure mercury vapor lamp. From the intermediate, as well as the ultimate photodegradation products isolated, it can be infered that photodegradation of (1) followed the proposed scheme. The biologica degradation of (1) and (2) by activated sludge under aerobic conditions was studied using equipment similar to that proposed by the OECD for determining the biodegradation of anionic synthetic surface active agents. Under the conditons applied, both FWAs were slowly biodegraded, within 30 days, whereas the photodegradation products of (1) were completely biodegraded within 14 days.

Biodegradation, Environmental↗
PubMed1983

Affinity labeling of erythrocyte band 3 protein with pyridoxal 5-phosphate. Involvement of the 35,000-dalton fragment in anion transport.

Transport of pyridoxal 5-phosphate (PLP) into erythrocytes was inhibited by inhibitors of anion transport including stilbene disulfonate compounds, indicating that it is mediated by Band 3 protein. When erythrocytes were treated with PLP and large amounts of free lysine and NaBH4, two membrane-spanning fragments of Band 3 (Mr = 17,000 and 35,000) were specifically labeled. When the cells were pretreated with 4,4'-dinitrostilbene 2,2'-disulfonate, the labeling in the 35,000-dalton fragment was inhibited. Erythrocytes labeled by PLP in both the 17,000- and 35,000-dalton fragments transported PLP at a decreased rate, whereas the cells labeled in only the 17,000-dalton fragment had essentially the same transport activity as the control when 4,4'-dinitrostilbene 2,2'-disulfonate was removed. The extent of inhibition of transport of inorganic phosphate in the labeled cells was similar to that of PLP. The results indicate that the 35,000-dalton fragment participates in the anion transport of the cell membrane.

Affinity Labels↗
PubMed1982

Role of ligandin as a binding protein and as an enzyme in the biliary excretion of sulfobromophthalein.

The effect of butylated hydroxyanisole (BHA; 600 mg/kg i.p. daily, for 10 days) and trans-stilbene oxide (TSO; 400 mg/kg i.p. daily, for 4 days) on the in vitro hepatic activity of glutathione transferases, the hepatic content of organic anion binding proteins and the plasma disappearance and biliary excretion of sulfobromophthalein (BSP), phenol-3,6-dibromsulphthalein disulfonate and [3H]ouabain was investigated in mice (BHA) and rats (TSO). Both BHA and TSO increased glutathione transferase activity toward BSP (360 and 200%), hepatic ligandin content (160 and 120%) and the biliary excretion of BSP (370 and 85%). BSP-glutathione excretion was enhanced, indicating that BSP conjugation was also stimulated in vivo. In contrast to BSP, biliary excretion of phenol-3,6-dibromsulphthalein disulfonate and organic anion which is not biotransformed but binds to ligandin, was unaltered or slightly increased (29%) after BHA or TSO treatment, respectively. TSO administration also did not affect the excretion of ouabain, a compound that neither binds to ligandin nor is biotransformed before excretion. Induction of ligandin failed to influence the initial disappearance of BSP, phenol-3,6-dibromsulphthalein disulfonate or ouabain from plasma, suggesting that induction had no marked effect on the hepatic uptake of these compounds. These studies suggest that ligandin plays a more important role in the biliary excretion of BSP due to its enzymatic rather than its binding properties.

Animals↗
PubMed1975

The chemistry of fluorescent whitening agents. Major structural types.

This gives a summary of those fluorescent whitening agents (FWAs) that have industrial importance. Firstly, a survey of the general physical and applicational properties is given, and then the chemistry of FWAs is dealt with. The FWAs are classified in six major structural classes: (A) stilbenes (B) coumarin and carbostyril compounds, (C) 1,3-DIPHENYL-2-PYRAZOLINES, (D) naphthalimides, (E) benzoxazolyl substitution products of conjugated systems, and (F) combined products of other heteroaromatics with ethylene or aromatic systems, owing to their methods of preparation and to their optical characteristics.

Chemical Phenomena↗
PubMed1994

Inhibition of mast cell Fc epsilon R1-mediated signaling and effector function by the Syk-selective inhibitor, piceatannol.

In RBL-2H3 rat tumor mast cells, antigens that cross-link the high affinity cell surface IgE receptor, Fc epsilon R1, activate at least two receptor-associated protein-tyrosine kinases, Lyn and Syk, and cause the tyrosine phosphorylation of the receptor beta and gamma subunits, PLC gamma 1, Vav, and other proteins. Cross-linking antigens also induce increased phosphatidylinositol turnover, Ca2+ mobilization, secretion, actin polymerization, spreading, and membrane ruffling. We have used the protein-tyrosine kinase inhibitor, piceatannol (3,4,3',5'-tetrahydroxy-trans-stilbene), to explore the coupling of specific kinases to cellular responses. Piceatannol preferentially inhibits the activity of Syk as compared with Lyn when added to in vitro assays with isolated enzymes. Treatment of RBL-2H3 cells with piceatannol strongly inhibits the antigen-stimulated activation of Syk measured in anti-Syk and anti-phosphotyrosine immune complex kinase assays at concentrations that have no effect on receptor subunit phosphorylation and maintain or increase the activity of Lyn in anti-phosphotyrosine immune complex kinase assays. In cells metabolically labeled with [32P]orthophosphate, piceatannol inhibits the antigen-stimulated tyrosine phosphorylation of Syk and most other proteins. However, receptor subunit phosphorylation is unchanged. Selective inhibition of Syk in this manner blocks receptor-mediated down-stream cellular responses (inositol 1,4,5-trisphosphate production, secretion, ruffling, and spreading) while having only minor effects when these responses are induced with drugs that bypass the receptor complex. These results reveal receptor-mediated Lyn activation as a relatively piceatannol-insensitive event that may contribute to receptor subunit phosphorylation and Syk activation but does not per se elicit cellular responses. Receptor-mediated Syk activation on the other hand is highly sensitive to piceatannol, is essential to Fc epsilon R1-mediated cellular responses, and, based on the increased phosphorylation of Lyn in piceatannol-treated cells, may be involved in terminating Lyn activity.

Animals↗
PubMed1994

Oligomeric forms of skate erythrocyte band 3. Effect of volume expansion.

Volume expansion of little skate (Raja erinacea) erythrocytes leads to the formation of oligomeric forms of the band 3 protein. The oligomers are formed following incubation in hypotonic media or inclusion of a permeant solute such as ethylene glycol. Oligomers were detected by specifically labeling the skate erythrocyte band 3 homolog with the radiolabeled stilbene [3H]4,4'-diisothiocyano-1,2 diphenylethane-2,2'-disulfonic acid and cross-linking membrane proteins with the homobifunctional agent bis(sulfosuccinimidyl) suberate. Under isoosmotic conditions, the distribution of band 3 in the monomer, dimer, and tetramer forms was 38, 54, and 8%. Medium of 0.5 osmolarity caused the distribution to change to 22% monomer, 31% dimer, and 47% tetramer. Upon return to isoosmotic conditions, cell volume, as well as the distribution of band 3 in the monomer, dimer, and tetrameric forms, returned to control values. Return of hypotonically swollen cells to isoosmotic conditions also returned taurine efflux back to control values. Hyperosmolarity caused a 20% shrinkage of cell volume but did not have any effect on either taurine efflux or the distribution of band 3 in the oligomeric forms. Pyridoxal 5'-phosphate and dinitrostilbene disulfonate, two agents that interact with and cause the formation of the tetrameric form of human band 3, also caused a shift toward to tetrameric peak in skate band 3. To determine whether the cross-linked oligomers had proteins that closely associate with band 3 in the intact cell, Western blots were performed to detect ankyrin and band 4.1. Neither protein appeared with the dimeric or tetrameric forms of band 3, suggesting that the mobility shift was in fact due to association of band 3 monomers. This is the first demonstration that oligomerization of band 3 occurs during a physiologic effect that may be mediated by the band 3 protein.

Animals↗
PubMed1993

Glutathione transferase activity in human vessels and in cultured arterial smooth muscle cells.

Glutathione transferases play an important role in the detoxification of many different endogeneous and exogenous compounds such as metabolites of polycyclic aromatic hydrocarbons (PAH) of cigarette tar. There is evidence that PAH may be atherogenic. The glutathione transferase activity towards trans-stilbene oxide (GST-tSBO) can be separated in blood in GST-positive and GST-negative phenotypes. We have previously suggested that the GST-negative phenotype may be associated with a higher morbidity in intermittent claudication among middle aged smokers. In the present study, GST-tSBO could easily be measured in human, rabbit and bovine arterial smooth muscle cells (SMC) in culture. The level of GST-tSBO was higher in rabbit than in bovine SMC. It was stable in bovine SMC during 5 cell passages and it could be induced twofold by long-time incubation with dimethylsulfoxide-soluble particulate matter from cigarette smoke or 3,4-benzo(a)pyrene. There was a positive correlation between the level of GST-tSBO in blood and in "healthy" arterial and venous tissue from individuals operated with coronary bypass. The enzyme levels in arterial tissue were lower than in venous tissue. GST-tSBO in atherosclerotic segments of human arteries was lower than in "healthy" segments from the same artery. These findings suggest that the arterial wall may have a low defense against toxic compounds that may decrease further as atherosclerosis proceeds. It is concluded that SMC are suitable for the study of the effects of PAH in relation to GST-tSBO and that the enzyme activity in blood will reflect the individual GST-tSBO phenotype also in vascular tissues.

Adult↗
PubMed1993

The glutathione S-transferase mu polymorphism as a marker for susceptibility to lung carcinoma.

Glutathione S-transferase (GST) enzymes detoxify carcinogens in tobacco smoke. Interindividual variation in GST function may be related to differences in risk for smoking-related cancer. Leukocytes from 50% of Caucasians lack GST activity toward trans-stilbene oxide (TSO), due to a deletion of the gene for the GST-mu enzyme. Presence of GST-TSO activity in leukocytes has been associated with low risk for lung cancer among cigarette smokers. We sought to determine whether GST activity in lung tissue is determined by the same gene polymorphism and whether it is associated with risk for lung cancer. Subjects were cigarette smokers, identified at the time of lung resection or autopsy in Seattle hospitals. Uninvolved lung tissue was obtained from 35 patients with lung carcinoma and 43 control patients and assayed for GST-mu activity with TSO, for the presence of the GST-mu gene product with an immunological assay, and for the GST-mu gene with Southern blotting. Mailed questionnaires were used to collect information on subjects' smoking histories and exposures which might alter enzyme activity. Interindividual results from the three assays correlated well. Smokers with high GST-TSO enzyme activity present in their lung tissue had a lower risk for lung carcinoma than did smokers with no or low activity (relative risk = 0.30; 95% confidence interval, 0.11-0.79), as did smokers with GST-mu antigen identified in lung tissue versus those with no antigen (relative risk = 0.30; 95% confidence interval, 0.11-0.79). Smokers with both maternal and paternal copies of GST-mu DNA (n = 7) had a lower cancer risk than smokers lacking GST-mu DNA (n = 30; relative risk = 0.35; 95% confidence interval, 0.06-2.10). High GST-mu activity appeared to be associated with a greater decrease in lung cancer risk among 38 heavy cigarette smokers (relative risk = 0.15; 95% confidence interval, 0.03-0.64) than among 38 light smokers (relative risk = 0.61; 95% confidence interval, 0.14-2.60). Presence or absence and number of copies of the GST-mu gene appear to determine activity of the GST-mu enzyme in lung. Smokers with the GST-mu enzyme have approximately one-third of the risk for lung carcinoma of smokers without the enzyme.

Adult↗
PubMed1996

Suppressed expression of phenobarbital-inducible hepatic cytochrome P-450s in Eisai-hyperbilirubinuria rats (EHBR/Eis).

The differential induction of hepatic cytochrome P-450 (P450) was studied in Eisai-hyperbilirubinuria rats (EHBR/Eis). This rat is a mutant that has as high a concentration of bilirubin in the urine as in the plasma. A single administration of trans-stilbene oxide (TSO, 2 mmol/kg), a phenobarbital (PB)-type P450 inducer, did not increase total P450, the CYP2B1/2 or the CYP2C6 in EHBR/Eis liver. TSO was able to induce delta-aminolevulinic acid synthetase and heme oxygenase, rate-limiting enzymes in heme biosynthesis and degradation, respectively, in both EHBR/Eis and Sprague-Dawley rat (SDR), the strain from which EHBR/Eis is derived. TSO also produced similar effects on glutathione depletion and on the activities of other drug-metabolizing enzymes in both strains. A 23-fold increase in CYP2B1/2 mRNA in the SDR liver was observed 24 hr after TSO treatment. In the EHBR/Eis strain, however, TSO increased CYP2B1/2 mRNA only 2-fold. In addition, repeated injection of TSO failed to induce P450 isozymes, CYP2B1/2, CYP2C6 or CYP3A2 in EHBR/Eis. On the other hand, there was essentially no difference in the induced levels of CYP1A1/2 apoprotein and mRNA between twins of SDR and EHBR/Eis livers treated with 3-methylcholanthrene or 1-benzylimidazole. The increased levels of both CYP2B1/2 apoprotein and mRNA from EHBR/Eis liver treated with TSO and 1-benzylimidazole were much smaller (2.5- and 5-fold increases, respectively) than from the SDR liver (17.5- and 15-fold increases, respectively). Although PB expressed CYP2B1/2 apoprotein and mRNA to a similar extent in both homozygous and heterozygous EHBR/Eis livers, CYP3A2 and CYP2C6 were less responsive to PB in homozygous EHBR/Eis. Repeated treatment with TSO induced these isozymes in heterozygote but not in homozygote. These findings suggest that the suppressed expression of PB-inducible P450 isozyme genes in the EHBR/Eis liver may be a general phenomenon associated with PB-type inducers. Therefore, EHBR/Eis may be experimentally useful for studying the mechanism of P450 induction by PB and PB-type inducers.

Animals↗
PubMedDate not supplied

Oncogene signal transduction inhibitors from medicinal plants.

Signal transduction is believed to be altered by cellular oncogenes or tumor suppressor genes during the transformation of normal cells into malignant cells. This proposition offers an attractive target for oncogene-based anticancer drug discovery from natural sources. Protein kinases encoded or modulated by oncogenes were used to prescreen the potential antitumor activity of medicinal plants. Protein-tyrosine kinase-directed fractionation and separation of the crude extracts of Polygonum cuspidatum and Koelreuteria henryi have led to the isolation of three different classes of protein-tyrosine kinase inhibitors, anthraquinone, stilbene and flavonoid. The anthraquinone inhibitor, emodin, displayed highly selective activities against src-Her-2/neu and ras-oncogenes.

Anthraquinones↗
PubMed1996

Radiation effects on polypropylene for sterilization.

In order to improve the resistance of gamma-radiation sterilization of polypropylene (PP), the formulations of the additives such as antioxidants, crosslinking agent, and trans-stilbene oxide (StO) have been carried out. The irradiated PP and ethylene-propylene copolymer samples with control and additives were characterized by mechanical tester, colorimetry, and Fourier transform infrared spectroscopy with total attenuated reflectance mode (FTIR-ATR). Crosslinking agent and StO formulated PP showed remarkable radiation resistance and minimum discoloration. Also, radiation resistance of ethylene-propylene copolymers with 3% of ethylene contents was better than that of PP homopolymers in the case of no additives. The proposed mechanisms of radiation stabilization with additives are also discussed.

Antioxidants↗
PubMed1976

Identification of monocytes in suspensions of mononuclear cells.

A new histochemical technique for morphological studies of mononuclear cells and granulocytes, based on fluorescent staining with methyl green, pyronine Y, and stilbene-isothiocyanato disulfonic acid (MPS stain) is described. The method was applied to mononuclear cells isolated from the blood of normal human subjects by Ficoll-Isopaque density centrifugation. Three cell populations were distinguished, mainly on the basis of differences in morphology and cytochemistry, utilizing the MPS stain. One of the cell types had many of the morphological characteristics of the monocyte. This technique, augmented by lysosomal content and endocytosis capacity studies, revealed contimination of the cell suspension with a larger percentage of monocytes than has usually been reported in the literature.

Cyanates↗