Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polycyclic Compounds”

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 1,045 records · Page 58Linked to original sources
PubMedDate not supplied

Determination of organic pollutants in reagent water by liquid-solid extraction followed by supercritical fluid elution.

A selected group of polynuclear aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, and phthalate esters in reagent water containing no particulate matter were separated and identified by liquid-solid extraction and supercritical fluid extraction (SFE). The water sample is first passed through a cartridge or disk containing a solid matrix coated with a chemically bonded C18 organic phase capable of extracting those organic compounds. The cartridge or the disk is then eluted with supercritical carbon dioxide to remove the compounds from the sorbent. Finally, the extract is injected into a capillary column gas chromatographic/quadruple mass spectrometric system. The precisions, percent recoveries of analytes using solvent elution, and percent recoveries using SFE are compared. The total analysis time is greatly reduced by using disk extraction and SFE in place of cartridge extraction and liquid-solvent elution. In addition, the waste solvent generated was minimized by using SFE.

Chemistry Techniques, Analytical↗
PubMed1977

Model studies in tumor incidence.

Two models of tumor incidence predicting the latency period as a function of the applied dose of a carcinogenic compound yield the same relationship as it has been empirically stated by Bryan and Shimkin (1,2). One model is based on a single-cell damage, the other one on a disturbtion of proliferation control within the cell population. The observed latency periods compared to the predicted values show that the tommunication model is a better basis for understanding chemical carcinogenesis than the single cell incidence.

Benz(a)Anthracenes↗
PubMed1988

Pah determination in samples of environmental interest.

Several compounds of the PAH class were determined in samples of various origin: from an urban solid waste incinerator (USWI), electric power plants, atmospheric precipitation, and from samples of soil close to pollution sources. Different analytical procedures were tested and employed to attain the most reliable data. In analyzing a variety of samples with respect to origin or mode of formation, the study demonstrated the ubiquitous nature of PAH and determined their quantitative and qualitative profile.

Air Pollutants↗
PubMed1999

Funalenone, a novel collagenase inhibitor produced by Aspergillus niger.

Funalenone, a phenalene compound that inhibits type I collagenase (MMP-1), was isolated from mycelium of Aspergillus niger FO-5904 by solvent extaction, ODS column chromatography, Sephadex LH-20 column chromatography and reversed phase HPLC. Funalenone inhibited 50% of type I collagenase activity at a concentration of 170 microM, but inhibited 18.3% and 38.7% against 72 kDa and 92 kDa type IV collagenase, respectively, at a concentration of 400 microM.

Aspergillus niger↗
PubMed1990

Redox properties of phenols, their relationships to singlet oxygen quenching and to their inhibitory effects on benzo(a)pyrene-induced neoplasia.

The inhibitory effects of synthetic phenolic compounds on benzo(a)pyrene-induced neoplasia of the mouse forestomach have been measured by Wattenberg et al. The efficiency of this inhibition has been estimated for each phenol, using R, the ratio of the number of tumors per mouse in the protected group over the number of tumours per mouse in the control group. We have observed a linear correlation between the chemoprotection efficiency R and the logarithm of the rate of quenching of singlet oxygen, k, by this family of phenols, log k being itself correlated with the one-electron oxidation potential of the phenols. These correlations suggest a charge transfer mechanism for the inhibition of neoplasia induced by benzo(a)pyrene. The correlations described provide a theoretical basis for scaling the inhibitors of mutagenicity induced by polycyclic aromatic compounds in terms of their oxidation potentials.

Animals↗
PubMed1997

Comparative molecular field analysis of a series of paclitaxel analogues.

A series of 94 paclitaxel analogues exhibiting antitumor activity by promoting the assembly of microtubules and inhibiting the disassembly process of microtubules to tubulin were investigated using the comparative molecular field analysis (CoMFA) method. These compounds belonging to 10 structural classes were randomly divided into a training set of 80 compounds and a test set of 14 compounds. Since the three-dimension structure of ligand--receptor complex is unknown, from X-ray and NMR data we rationally selected the three-dimension structure of paclitaxel in a polar solution as the active conformation and starting structure for molecule modeling, the other molecules were aligned using this molecule model as the template. The most optimal CoMFA yielded a two-components model, with significant cross-validation r2cv of 0.640 and conventional r2 of 0.868. The predictive ability of training set model was tested on the test set of 14 compounds. The tests not only revealed the robustness of the CoMFA model but demonstrated that for our model r2pred based on the mean activity of test set compounds can accurately estimate external predictivity but r2pred based on the mean activity of training set compounds overestimated the model. The CoMFA model explained why the activity of taxoid is sensitive to the stereochemistry of the atoms at C-2' and C-3' positions and the presence of hydroxyl group at C-2' position. The other factors affecting activity were also elucidated according to standard coefficient contour maps of steric and electrostatic fields derived from the CoMFA model.

Antineoplastic Agents↗
PubMed1981

Metal interactions in carcinogenesis: enhancement, inhibition.

Metals constitute a fundamentally important part of the total human environment. Since human exposure often involves complex mixtures of metal compounds and, possibly, organic compounds which may be carcinogenic per se, interactions between these compounds may add significantly to human cancer risk. Our present knowledge about these kinds of interactions is very limited. The best investigated area is benzo(a)pyrene (BP)-metal oxide particle interactions in respiratory carcinogenesis in the hamster. Metal oxide particles were also shown to modify the carcinogenic effect of nitrosamines. Several reports describe experiments in which selenium compounds exerted a generally anticarcinogenic and antimutagenic activity. Inorganic arsenic compounds, which are accepted to be carcinogenic in man, have so far been negative in animal experiments except for one recent suggested report. Several authors have, however, suggested that these compounds may act as cocarcinogens due to their inhibition of DNA repair, although animal experiments to demonstrate a cocarcinogenic effect of arsenic compounds have been negative so far, except for one preliminary report. The concentration of zinc in the diet seemed to influence both transplanted tumor growth and the carcinogenicity of several organic compounds, and the possibility of a correlation between dietary zinc and certain cancer forms in man has been suggested. Protection against development of Leydigiomas usually induced by cadmium injection was afforded by simultaneous injection of zinc salts. Nickel carcinogenesis has been reported to be antagonized by manganese, and synergism between Ni and organic carcinogens, e.g. BP, has been demonstrated. There is no firm evidence that lead may be a cocarcinogen, although some limited experimental evidence is available. Oxidizing agents have been demonstrated to increase, and reducing agents to antagonize, the mutagenic effect of chromium compounds in vitro. The content of carcinogenic and other metals in asbestos has been suggested to modify the carcinogenic properties of asbestos. Since much of the information available at present is suggestive, further research on these interactions as well as other possible interactions in metal carcinogenesis is needed. Studies should be made both in well defined in vitro systems and in relevant animal models.

Animals↗
PubMed1985

Correlations for the acute toxicity of multiple nitrogen substituted aromatic molecules.

Twenty-nine compounds, including amino and nitro derivatives of aromatic hydrocarbons as well as azaarenes and indole analogs, were assayed. The biological activity was monitored as population growth to axenic cultures of the ciliate Tetrahymena pyriformis. Structure-activity relationships were examined by linear regression analysis of log biological activity (Y) and log 1-octanol/water partition coefficient (X). Partition coefficients were determined by linear regression analysis of the retention time index of HPLC data. Attempts to generate linear predictive correlations for all the test compounds (n = 29; r2 = 0.325; P greater than 0.0013) and groups, subdivided based on the following chemical classes: aromatic hydrocarbons (n = 13; r2 = 0.122; P greater than 0.2417), azaarenes (n = 9; r2 = 0.348; P greater than 0.0946) and indole analogs (n = 7; r2 = 0.743; P greater than 0.0126), met with little success. Similarly, subdivisions based on the presence of a single (n = 14; r2 = 0.514; P greater than 0.0039) or multiple H-polar groups, i.e., NO2, NH2 (n = 15; r2 = 0.195; P greater than 0.0996), met with little success also. However, if one segregates the compounds which have para oriented H-polar substituents one gets a strong linear predictive correlation (n = 11; r2 = 0.889; P greater than 0.0001). A subdivision of the remaining data set leads to two models (n = 11; r2 = 0.845; P greater than 0.0001) and (n = 7; r2 = 0.965; P greater than 0.0001). An examination of the toxicity partitioning product values suggests the three-line predictive correlation model of these data is valid.

Animals↗
PubMed2006

Synthesis and monoamine transporter affinity of front bridged tricyclic 3beta-(4'-halo or 4'-methyl)phenyltropanes bearing methylene or carbomethoxymethylene on the bridge to the 2beta-position.

A series of front bridged tricyclic 3beta-(4'-halo or 4'-methyl)phenyltropanes bearing methylene or carbomethoxymethylene on the bridge to the 2beta-position was synthesized, and their binding affinities were determined in cells transfected to express human norepinephrine transporter (NET), serotonin transporter (SERT), and dopamine transporter (DAT) via competition binding assays. All compounds studied in this series exhibit a moderate to high potency at all three transporters with SERT or DAT selectivity. 3beta-(4'-iodo)phenyltropane bearing methylene on the bridge to the 2beta-position (24) presents a particularly attractive pharmacological profile, with very high SERT affinity (K(i) = 0.09 nM) and selectivity versus NET (65-fold) and DAT (94-fold).

Animals↗
PubMed1980

Environmental pollution and pregnancy: risks and uncertainties for the fetus and infant.

Numerous environmental contaminants can affect the developing embryo, fetus, or infant. This essay explores such questions as these: What is the importance in mutagenesis and teratogenesis of macroenvironmental pollutants such as the heavy metals, dioxin derivatives, polychlorinated diphenyl compounds, and pesticides? What is the significance of microenvironmental pollutants (or social environmental factors) such as tobacco smoke, alcohol, and pharmacologic agents over which exposed individuals have considerable control? What are some of the ethical and legal implications of these toxins of which clinicians should be aware?

Air Pollutants, Radioactive↗
PubMed1982

Pharmacological properties of Dibenzo[a,c]cyclooctene derivatives isolated from Fructus Schizandrae Chinensis III. Inhibitory effects on carbon tetrachloride-induced lipid peroxidation, metabolism and covalent binding of carbon tetrachloride to lipids.

Fructus Schizandrae, a traditional Chinese tonic, has been shown to lower the elevated serum glutamic pyruvic transaminase (SGPT) levels of patients with chronic viral hepatitis and several of its components decrease the hepatotoxicity of carbon tetrachloride (CCl4) in animals. This paper deals with the mechanism of protection against CCl4-hepatotoxicity of these compounds as well as of DDB, a synthetic analogue of Schizandrin (Sin) C. Of the seven components, Sin B and C, Schizandrol (Sol) B, Schizandrer (Ser) A and B, as well as dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxy-biphenyl-2,2'-dicarboxylate (DDB) were shown to inhibit CCl4-induced lipid peroxidation and [14C]Cl4 covalent binding to lipids of liver microsomes from phenobarbital(PB)-treated mice. The compounds also decreased carbon monoxide (CO) production and cofactor (NADPH, oxygen) utilization during CCl4 metabolization by liver microsomes. It may be postulated, therefore, that the hepatoprotective effect of certain components isolated from Fructus Schizandrae as well as DDB is due to their inhibitory effect on CCl4-induced lipid peroxidation and the binding of CCl4-metabolites to lipids of liver microsomes.

Animals↗
PubMed2002

Carboxyethylester-polyrotaxanes as a new calcium chelating polymer: synthesis, calcium binding and mechanism of trypsin inhibition.

A carboxyethylester-polyrotaxane was synthesized as a novel calcium chelating polymer in the field of oral drug delivery and characterized in terms of mechanism of trypsin inhibition. Here, carboxyethylester (CEE) groups are introduced to all the primary hydroxyl groups in alpha-cyclodextrins (alpha-CDs), which are threaded onto a poly(ethylene glycol) chain capped with bulky end-groups (polyrotaxane). The solubility of the CEE-polyrotaxane in physiological conditions increased with pH, indicating ionization-related solubility similar to conventional polyacrylates. The ability of calcium (Ca2+) chelation was found to increase in the order of poly(acrylic acid) (PAA)>CEE-polyrotaxanez.Gt;CEE-alpha-CD, suggesting that the increased density of carboxyl groups enhances the Ca2+ chelating ability. The activity of trypsin was inhibited by these compounds in the same order of the calcium chelation. However, the inhibitory effect of CEE-polyrotaxane was reduced by adding excess Ca2+ without precipitation that was observed in the presence of PAA. Such the reduced inhibition and precipitation by CEE-alpha-CD was not observed. Therefore, the inhibitory effect of CEE-polyrotaxane is due to Ca2+ chelation from trypsin without non-specific interaction.

Acrylic Resins↗
PubMedDate not supplied

A solid phase library synthesis of hydroxyindoline-derived tricyclic derivatives by Mitsunobu approach.

Hydroxyindoline-derived scaffold, 9, was synthesized with the goal of generating a library of indoline-based natural product-like tricyclic derivatives to be utilized as small-molecule chemical probes. The tricyclic ring was obtained by a Mitsunobu reaction of the N-nosyl amino acid conjugate with the primary hydroxyl group. The solid-phase synthesis was achieved by immobilizing scaffold 9 onto the solid support giving a compound, 15. This was then subjected to a series of reactions on solid phase, including the Mitsunobu reaction, leading to the desired indoline-derived tricyclic derivative. The final product has two diversity sites: (i) amino acid as the first diversity and (ii) amidation of the secondary amine for the second diversity. These two diversity sites were utilized in the library generation by IRORI split-and-mix approach.

Hydroxyl Radical↗
PubMed1985

Toxic chemicals in sediments and biota from a creosote-polluted harbor: relationships with hepatic neoplasms and other hepatic lesions in English sole (Parophrys vetulus).

High prevalences of idiopathic hepatic lesions, including neoplasms (e.g., hepatocellular carcinomas, cholangiocellular carcinomas) (27%, 20 of 75 fish) and foci of cellular alteration (putative 'preneoplastic' lesions) (44%, 33 of 75 fish), were found in English sole (Parophrys vetulus) exposed to creosote-contaminated sediments in Eagle Harbor, Puget Sound, WA. Sediments from the contaminated region of the harbor contained particularly high concentrations of aromatic hydrocarbons (e.g., benzo[a]pyrene and benz[a]anthracene), and a variety of nitrogen-containing aromatic compounds (e.g., carbazole and acridine). The composition of the aromatic compounds was characteristic of creosote. Dramatically lower concentrations of aromatic compounds were found in sediments from a reference site in which the bottom-dwelling fish examined were free of detectable neoplastic or 'preneoplastic' hepatic lesions. Food organisms in the stomachs of the English sole from Eagle Harbor contained substantially higher concentrations of aromatic hydrocarbons than comparable organisms from the reference site. The concentrations of individual aromatic hydrocarbons in muscle and liver from the Eagle Harbor fish were low; however, high concentrations of metabolites of aromatic compounds were present in the bile. The findings strongly suggest an association between exposure to creosote and the prevalence of hepatic lesions, including neoplasms, in the bottom-dwelling fish, and furthermore support the putative role of aromatic hydrocarbons in liver carcinogenesis in fish.

Animals↗
PubMed2005

Selected persistent organic pollutants (POPs) in the Italian environment.

The ratification of the Stockholm Convention on Persistent Organic Pollutants is a departure point for several considerations on their presence in environmental matrices. In this paper, the Italian situation is presented with emphasis on the most toxic compounds--chemicals with dioxin-like toxic action, and the activity in the area of interest of the Istituto Superiore di Sanità. Biotic, as well as abiotic matrices have been taken in consideration and, where possible, a comparation between their contamination levels with the levels reported on similar matrices by other European countries has been reported.

Adipose Tissue↗
PubMed1981

[Damage factors in tobacco and tobacco smoke].

In the last 30 years the production and consumption of cigarettes are increasing permanently. Till now more than 2200 noxious substances have been detected in the smoke of cigarettes. The origin and the synthesis of selected groups of these compounds and their distribution on main- and on sidestream smoke are described, furthermore the possibilities for estimation and control of nicotine abuse are reviewed. The incorporation of noxious substances of tobacco smoke result in a damage of clearance mechanisms of the lung and a change of loading by drugs and other metabolisable noxious substances, because the biotransformation processes are influenced by tobacco smoke. In this connection the importance of aryl-hydrocarbon-hydroxylase is discussed.

Aryl Hydrocarbon Hydroxylases↗
PubMed1977

An in vitro study on the interaction between dimethylnitrosamine and nucleic acids via a microsomal system.

Radioactive alkylated bases, ribose or phosphate, were never found either in acid and alkaline hydrolysates of polyribonucleotides or in alkaline hydrolysates of DNA after incubation with 14C-dimethylnitrosamine (DMNA) in a microsomal system. Two radioactive compounds, which were co-chromatographed with methylamine and N-methylhydrazine, respectively, on column, paper, and thin-layer, were always detected. They differed from the compound derived from 7-methylguanosine after the alkali-mediated fission of the imidazole ring in its molecule. The in vitro system employed well represents the in vivo situation (7-methylguanine which is liberated from DNA after acid hydrolysis); however, it has given results which do not agree with the generally-accepted mechanism of DMNA alkylation at the N-7 position of guanine.

Animals↗
PubMedDate not supplied

Occupational exposure to bitumen during road paving.

The exposure of road pavers to total particulates, bitumen fumes, semivolatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), low-molecular-weight amines, styrene, and 1,3-butadiene was studied at 13 paving sites where 11 different asphalt mixtures were laid. Researchers analyzed 1-hydroxypyrene in the workers' pre- and postshift urine samples. The arithmetic mean concentrations of total particulates, bitumen fumes, SVOCs, and PAHs in the breathing zone of road pavers were 0.6 mg/m3, 0.29 mg/m3, 5.6 mg/m3, and 5.03 microg/m3, respectively. The highest bitumen fume concentrations (2.65 mg/m3) were measured in manual mastic laying, that is, when the paving temperature was highest. More than 90% of air impurities measured were in the vapor phase. Workers laying surface dressing were exposed to the highest SVOC concentrations (27.8 mg/m3). The paving temperature and the concentrations of bitumen fume correlated positively, but the weather conditions significantly affected the workers' exposure; for example, increased wind velocity resulted in lower concentrations of SVOCs and PAHs. Job title was not found to be a significant determinant of exposure, but exposure to bitumen fume and greater than or equal to four-ring PAHs among manual mastic pavers, and that to SVOCs and total PAHs among surface dressing workers, were significantly higher than among other pavers. Exposure during road paving operations was, on average, more than 10-fold higher to PAHs than was the exposure of a traffic controller (0.34 microg/m3) caused by automobile exhausts from background traffic. The PAHs were comprised mainly of two- and three-ring compounds. The concentrations of amines, and impurities from polymer modified bitumens, styrene, and 1,3-butadiene were below detection limits. Urinary 1-hydroxypyrene concentrations were higher among road pavers than among office workers serving as referents.

Air Pollutants↗