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At least 793 records · Page 44Linked to original sources
PubMed2002

Organ-specific analysis of phenylphenalenone-related compounds in Xiphidium caeruleum.

The distribution pattern of phenylphenalenone-type compounds was investigated in vegetative and reproductive organs of Xiphidium caeruleum. The highest total molar concentration, up to 30 micromol g(-1) fr. wt, was detected in the root tip and the stamen. Accumulation of specific phenylphenalenone-related metabolites including glycosides was found in the hypogeal plant parts, the leaves, and the reproductive organs of the inflorescence. Putative biosynthetic relationships and the role of these compounds in plant defence are discussed.

Chromatography, High Pressure Liquid↗
PubMed2006

Selection of retapamulin, a novel pleuromutilin for topical use.

The in vitro activity of retapamulin was determined and compared to that of topical and community antibiotics. The MIC(90)s of retapamulin against Staphylococcus aureus and Streptococcus pyogenes were 0.12 microg/ml and 0.016 microg/ml, respectively. Retapamulin has a low propensity to select resistance and produces an in vitro postantibiotic effect.

Anti-Infective Agents, Local↗
PubMed1998

[Total synthesis of schizandrin, the main active ingredient isolated from the Chinese herbal medicine fructus schizandrae].

In this paper, schizandrin(9), the main active ingredient isolated from Schisandra chinensis, was synthesized from gallic acid by a new route. This route consists of only nine steps, including reductive-coupling reaction of compound(5) and dehydryoxylatic reaction of compound(6) to give compounds(7Z, 7E). By hydroboration, compound (8) was obtained from compound(7Z). With the presence of thallium trifluoroacetate (TTFA) and 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone (DDQ) compound (9) is obtained from compound (8) by intramolecular nonphenolic oxidative coupling. These compounds were identified by elemental analysis, MS, UV, IR and NMR spectra.

Cyclooctanes↗
PubMed2000

New synthetic approaches to polycyclic aromatic hydrocarbons and their carcinogenic oxidized metabolites: derivatives of benzo[s]picene, benzo[rst]pentaphene, and dibenzo[b,def]chrysene.

A new synthetic approach to polycyclic aromatic compounds is described that entails in the key steps double Suzuki coupling of PAH bisboronic acid derivatives with o-bromoaryl aldehydes to furnish aryl dialdehydes that are converted to larger polycyclic aromatic ring systems by either (a) conversion to diolefins by Wittig reaction followed by photocyclization or (b) reductive cyclization with triflic acid and 1,3-propanediol. This synthetic method provides convenient access to as many as three different polycyclic aromatic ring systems from a single Suzuki coupled intermediate. It was utilized to synthesize substituted derivatives of benzo[s]picene, benzo[rst]pentaphene, dibenzo[b,def]chrysene, and 13,14-dihydro-benz[g]indeno[2,1-a]fluorene, as well as the putative carcinogenic bisdihydrodiol metabolites of benzo[s]picene, benzo[rst]pentaphene, and dibenzo[b,def]chrysene.

Benzopyrenes↗
PubMed2005

Gas- and particulate-phase specific tracer and toxic organic compounds in environmental tobacco smoke.

Cigarette smoke constituents are worthy of concern and characterized as carcinogens. Different experiment conditions may affect the environmental tobacco smoke (ETS) constituents. A study was undertaken in a 75.5-m3 spare office to evaluate ETS constituents in a real environment. Thirty-four volatile organic compounds (VOCs) including three ETS tracers: nicotine, 2,5-dimethylfuran and 3-ethenylpyridine (3-EP), 19 carbonyl compounds, 54 semi-volatile compounds (24 polycyclic aromatic hydrocarbons (PAHs) and 30 alkanes) as well as CO and total particulate matter (TPM) from 15 leading commercial brands were determined. ETS constituents did not increase with increasing cigarette tar. ETS tracers nicotine and 3-EP were affected greatly due to more sorption and surface reactions in real world compared to other studies conducted in chamber, which resulted in 2-5 times lower. Benzene, toluene, ethylbenzene, xylenes, acrolein, 2-butanone and the high molecular weight compounds exhibited little affect. Pearson correlation analyses show that gas-phase and particulate-phase ETS tracers did not show significant correlation, but within each homologue many of compounds correlated significantly. Indole and cholesta-3,5-diene were also detected in ETS. These results may be useful in efforts to better understand the health effect of ETS exposure and source apportionment.

Furans↗
PubMed2000

Novel use of a dual-zone restricted access sorbent: normal-phase solid-phase extraction separation of methyl oleate from polynuclear aromatic hydrocarbons stemming from semi-permeable membrane devices.

A normal-phase solid-phase extraction (SPE) method was developed utilizing a dual-zone restricted-access sorbent to separate methyl oleate from the 16 US Environmental Protection Agency priority-pollutant polynuclear aromatic hydrocarbons in a hexane matrix. This technique represents a new development in SPE methodology expanding the limited number of available normal-phase SPE sorbents. While based on a specific application (removal of methyl oleate from semipermeable membrane device extracts), this cleanup method could easily be adapted for other uses requiring the removal/isolation of methyl oleate and potentially related compounds.

Chromatography, Gas↗
PubMed2002

Cyclotriveratrylene (CTV) as a new chiral triacid scaffold capable of inducing triple helix formation of collagen peptides containing either a native sequence or Pro-Hyp-Gly repeats.

A new triacid scaffold is described based on the cone-shaped cyclotriveratrylene (CTV) molecule that facilitates the triple helical folding of peptides containing either a unique blood platelet binding collagen sequence or collagen peptides composed of Pro-Hyp-Gly repeats. The latter were synthesized by segment condensation using Fmoc-Pro-Hyp-Gly-OH. Peptides were coupled to this CTV scaffold and also coupled to the Kemp's triacid (KTA) scaffold. After assembly of peptide H-Gly-[Pro-Hyp-Gly]2-Phe-Hyp-Gly-Glu(OAll)-Arg-Gly-Val-Glu (OAll)-Gly-[Pro-Hyp-Gly]2-NH2 (13) by an orthogonal synthesis strategy to both triacid scaffolds, followed by deprotection of the allyl groups, the molecular constructs spontaneously folded into a triple helical structure. In contrast, the non-assembled peptides did not. The melting temperature (Tm) of (+/-) CTV[CH2C(O)N(H)Gly-[Pro-Hyp-Gly]2-Phe-Hyp-Gly-Glu-Arg-Gly-Val-Glu-Gly- [Pro-Hyp-Gly]2-NH2]3 (14) is 19 degrees C, whereas KTA[Gly-Gly-[Pro-Hyp-Gly]2-Phe-Hyp-Gly-Glu-Arg-Gly-Val-Glu-Gly- [Pro-Hyp-Gly]2-NH2]3 (15) has a Tm of 20 degrees C. Thus, it was shown for the first time that scaffolds were also effective in stabilizing the triple helix of native collagen sequences. The different stabilizing properties of the two CTV enantiomers could be measured after coupling of racemic CTV triacid to the collagen peptide, and subsequent chromatographic separation of the diastereomers. After assembly of the two chiral CTV scaffolds to the model peptide H-Gly-Gly-(Pro-Hyp-Gly)5-NH2 (24), the (+)-enantiomer of CTV 28b was found to serve as a better triple helix-inducing scaffold than the (-)-enantiomer 28a. In addition to an effect of the chirality of the CTV scaffold, a certain degree of flexibility between the CTV cone and the folded peptide was also shown to be of importance. Restricting the flexibility from two to one glycine residues resulted in a significant difference between the two collagen mimics 20a and 20b, whereas the difference was only slight when two glycine residues were present between the CTV scaffold and the peptide sequence in collagen mimics 30a and 30b.

Circular Dichroism↗
PubMed1996

Effects of Schisandrin B and alpha-tocopherol on lipid peroxidation, in vitro and in vivo.

Effects of Schisandrin B (Sch B) and alpha-tocopherol (alpha-TOC) on ferric chloride (Fe3+) induced oxidation of erythrocyte membrane lipids in vitro and carbon tetrachloride (CCl4) induced lipid peroxidation in vivo were examined. While alpha-TOC could produce prooxidant and antioxidant effect on Fe(3+)-induced lipid peroxidation, Sch B only inhibited the peroxidation reaction. Pretreatment with alpha-TOC (3 mmol/kg/day x 3) did not protect against CCl4-induced lipid peroxidation and hepatocellular damage in mice, whereas Sch B pretreatment (0.3 mmol/3.0 mmol/kg/day x 3) produced a dose-dependent protective effect on the CCl4-induced hepatotoxicity. The ensemble of results suggests that the ability of Sch B to inhibit lipid peroxidation, while in the absence of pro-oxidant activity, may at least in part contribute to its hepatoprotective action.

Animals↗
PubMed1996

Monitoring of nitropolycyclic aromatic hydrocarbons in food using gas chromatography.

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) were determined in different kinds of food. The investigation of food matrices necessitates the development of appropriate analytical procedures for sensitive monitoring and determination of these compounds. The analysis of the nitro-PAHs was carried out by GC/MSD, GC plus mass spectrometry, and GC/NPD (nitrogen-phosphorus detection) GC plus nitrogen-phosphorus detection. Seven nitro-PAHs were positively identified and quantified in vegetables, smoked and grilled foods, oil, tea, coffee and spices.

Animals↗
PubMed2001

Environmental and biological monitoring of traffic wardens from the city of Rome.

A molecular epidemiological study on Roman policemen is ongoing. The results of a first assessment of the occupational exposure to aromatic compounds of 66 subjects engaged in traffic control and of 33 office workers are presented in this paper. Passive personal samplers and urinary biomarkers were used to assess exposure to benzene and polycyclic hydrocarbons during work shifts. The results obtained indicate that benzene exposure in outdoor workers is about twice as high as in office workers (geometric mean 7.5 and 3.4 micrograms/m3, respectively). The distribution of individual exposure values was asymmetrical and skewed toward higher values, especially among traffic wardens. Environmental benzene levels recorded by municipal monitoring stations during work shifts (geometric mean 11.2 micrograms/m3) were in the first instance comparable to or greater than individual exposure values. However, several outlier values were observed among personal data that greatly exceeded average environmental benzene concentrations. Among the exposure biomarkers investigated, only blood benzene correlated to some extent with previous exposure to benzene, while a seasonal variation in the excretion of 1-hydroxypyrene and trans-muconic acid was observed in both study groups. In conclusion, these results suggest that outdoor work gives a greater contribution than indoor activities to benzene exposure of Roman citizens. Moreover, relatively high-level exposures can be experienced by outdoor workers, even in the absence of large-scale pollution episodes.

Adult↗
PubMed1985

Identification and quantification of a messenger ribonucleic acid induced by polynuclear aromatic hydrocarbons--using a cloned human cytochrome P-450 gene.

We have isolated four overlapping human genomic clones associated with the polynuclear aromatic hydrocarbon-induced form of cytochrome P-450. The form of P-450 most closely associated with polynuclear aromatic hydrocarbons induction has been defined as P1-450. These four overlapping genomic clones span a total of 31.0 X 10(3) base pairs in length with the coding sequence lying in the center of these clones. Translation in vitro of 3-methylcholanthrene-induced mRNA, selected with the human P1-450 genomic clone, detect a protein with Mr 52000, which is immunoprecipitable by the anti-(mouse P1-450) antibody. The isolated human P1-450 genomic clone hybridizes to 3-methylcholanthrene-induced mRNA from monkey liver, benzanthracene and 3-methylcholanthrene-treated human mammary tumor cells (MCF-7), but not to isosafrole-treated human cells. Upon treatment with polynuclear aromatic hydrocarbons there is a positive correlation between induced arylhydrocarbon hydroxylase (flavoprotein-linked monoxygenase) activity and the amount of mRNA that hybridizes to the isolated human genomic clone for P1-450. The size of mRNA, induced from human cells and monkey liver by polynuclear aromatic hydrocarbons, is around 3.3 X 10(3) base pairs, which is the same as the larger of two mRNA induced by polynuclear aromatic hydrocarbons in the inbred strain of mouse (C57BL/6N). Our data also showed that the isolated DNA clone can detect a mRNA size of 3.3 X 10(3) base pairs from phytohemagglutinin-activated, benzanthracene-treated human lymphocytes. Densitometer scanning indicated the presence of a 3.6-fold variation (highest-lowest) in the levels of lymphocyte P1-450 mRNA contents among six individuals studied.

Animals↗