Characterization of toxic compound in thermally oxidized oil.
Explore the source record for details and available documents.
Air↗
SEARCH · PubMed Health
Results for “Spectrophotometry, Infrared”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Studies on chemical nature of lipofusion (age pigment) isolated from normal human brain.
Human brain lipofusion isolate was studied for its purity and physical and chemical properties. Purification of the inpure material was achieved by gel permeation chromatography using Sephadex LH-20 and BioBeads S-X1 gels. The purified lipofusion polymer represented ca. 12% of the starting material with the rest of the material being various mixed lipids. The mol wt of the purified lipofuscin was determined to be between 6000-7000 daltons. IR, UV-visible, NMR, and fluorometric spectra were obtained, all indicating the fundamentally lipid nature of lipofuscin. The NMR spectrum strongly resembled that of a typical long chain fatty acid. Numbers of fatty acids and several amino acids were present as a portion of the lipofuscin structure. The results obtained suggested that the brain lipofuscin employed in the present study consisted mainly of polymeric lipid and phospholipid structures along with amino acids either bound to the lipids or as included proteins.
Brain Chemistry↗
Complex formation and reversible oxygenation of free fatty acids.
Explore the source record for details and available documents.
Binding Sites↗
A radical scavenging reaction of alpha-tocopherol with methyl radical.
To study a radical scavenging reaction of alpha-tocopherol, it was reacted with methyl radical in dimethyl sulfoxide. Two main products, a geminal dimethyl cyclohexadienone and methyl ether of alpha-tocopherol, were obtained and these structures were determined by 13C nuclear magnetic resonance spectroscopy. The radical methylation data of alpha-tocopherol suggested that a delocalize radical species would be an intermediate.
Chemical Phenomena↗
Radical scavenging reactions of alpha-tocopherol. II. The reaction with some alkyl radicals.
alpha-Tocopherol was reacted with some alkyl radicals (ethyl, n-propyl, iso-propyl, n-butyl, and sec-butyl radical) to study its radical scavenging reactivity. The two types of products (alkyl ethers of alpha-tocopherol and cyclohexadienones) were obtained on treatment of each radial. These structures were determined by the spectral analysis. It was observed that alpha-tocopherol is very sensitive to the alkyl racidals and that the yields of the cyclohexadienones are decreased and that of the alkyl ethers are not much varied with an increase of carbon numbers of the alkyl radicals.
Chemical Phenomena↗
Characterization of bovine rumen liquor isoprenoid hydrocarbons with reference to dietary phytol.
The isoprenoid hydrocarbon, trans-phyt-2-ene (82.2%), phyt-1-ene (6.5%), and phytane (11.3%), were detected in bovine rumen liquor by means of AgNO3-impregnated thin layer chromatography and gas liquid chromatography with mass spectrometry and infrared spectrophotometry. The unsaturated hydrocarbons were identified by comparing their chromatographic, physical, and chemical properties with those of synthetic isoprenoid hydrocarbons prepared from dihydrophytol. The natural level of the original isoprenoid components within the rumen is comprised of phytol and dihydrophytol (of the ratio of 2:1). These represented at least 60% of the total free fatty alcohol content of the rumen liquor lipid extract and could, therefore, be the origin of the isoprenoid hydrocarbons observed.
Animals↗
The preparation, gas liquid chromatography, and some physical and chemical properties of certain higher aliphatic 2,4-diketones--a new lipid class.
Fourteen saturated aliphatic 2,4-diketones, ranging in chain length from C7 to C25, and one unsaturated compound, delta12-2,4-heneicosenedione, were prepared by Claisen acylations of the appropriate methyl ketones, and their gas chromatographic behavior was studied. Mixtures of these diketones were resolved on columns containing UCW98 or Carbowax 20M stationary phases. Their methoxime and 2,4-dinitrophenylsemicarbazone derivatives were resolved on OV-17 and OV-1 stationary phases, respectively. Since higher homologous aliphatic 2,4-diketones have been found in mammalian tissues, they constitute a new lipid class.
Chromatography, Gas↗
The identification of the allylic nitrite and nitro derivatives of methyl linoleate and methyl linolenate by negative chemical ionization mass spectroscopy.
The autoxidation of polyunsaturated fatty acids is initiated both in vivo and in vitro by nitrogen dioxide. The mechanism of the initiation process is believed to involve both addition reactions and hydrogen atom abstraction reactions, with hydrogen abstraction predominating at low levels of nitrogen dioxide. Therefore low levels of nitrogen dioxide should react with polyunsaturated fatty acids to give allylic derivatives; in an anaerobic system these derivations should be allylic nitro and nitrite compounds. Using negative methane chemical ionization mass spectrometry and other analytical techniques, we have identified these allylic nitrite and nitro compounds from the reactions of low levels of nitrogen dioxide with methyl linoleate and methyl linolenate in the absence of oxygen.
Chromatography, High Pressure Liquid↗
The interaction of the vanadyl(IV) cation with phytic acid.
The interactions of VO2+ with phytate to form both soluble and insoluble complexes, have been studied by electronic absorption spectroscopy. A soluble 1:1 VO2+:phytate complex is formed at pH < 1. At higher pH-values insoluble complexes are produced. Two different solid complexes, obtained respectively at pH = 2 and 4, were isolated and characterized. The maximal bonding ratio of VO2+:phytate was found to be 4, on the basis of a pH binding profile.
Electrochemistry↗
Steroid derivatives. LXXVIII. Microbial 7-hydroxylation of some steroid substances of the androstane group by the action of Absidia orchidis.
Explore the source record for details and available documents.
Anabolic Agents↗
Eurotium (Aspergillus) repens metabolites and their biological activity.
Eurotium repens mycelium cultivated under static conditions was used to isolate and identify metabolities--echinulin, physcion, erythroglaucin, flavoglaucin and asperentin; the filtrate of the culture yielded asperentin 8-methylether. The broadest biological activity spectrum was displayed by asperentin which had antibacterial and antifungal effects and, at a concentration of 86 microgram/ml, caused 50% mor7 tality in Artemia saline larvae. The highest cytotoxicity towards HeLa cells was found in physcion which caused 50% growth inhibition at a concentration of 0.1 microgram/ml.
Animals↗
The role of the hydrophobic group on ring A of chalcones in the inhibition of interleukin-5.
Novel chalcones were found as potent inhibitors of interleukin-5 (11-5). 1-(6-Benzyloxy-2-hydroxyphenyl)-3-(4-hydroxyphenyl)propenone (2a, 78.8% inhibition at 50 microM, IC50 = 25.3 microM) was initially identified as a potent inhibitor of IL-5. This activity is comparable to that of budesonide or sophoricoside (1a). The benzyloxy group appears to be critical for the enhancement of the IL-5 inhibitory activity. To identify the role of this hydrophobic moiety, cyclohexyloxy (2d), cyclohexylmethoxy (2c), cyclohexylethoxy (2e), cyclohexylpropoxy (2f), 2-methylpropoxy (2g), 3-methylbutoxy (2h), 4-methylpentoxy (2i), and 2-ethylbutoxy (2j) analogs were prepared and tested for their effects on IL-5 bioactivity. Compounds 2c (IC50 = 12.6 microM), 2d (IC50 = 12.2 microM), and 2i (IC50 = 12.3 microM) exhibited the most potent activity. Considering the cLog P values of 2, the alkoxy group contributes to the cell permeability of 2 for the enhancement of activity, rather than playing a role in ligand motif binding to the receptor. The optimum alkoxy group in ring A of 2 should be one that provides the cLog P of 2 in the range of 4.22 to 4.67.
Cell Line↗
Anti-inflammatory activity of flavonoids from Populus davidiana.
An in vitro bioassay-guide revealed that the methanol (MeOH) extract of the stem bark of Populus davidiana showed considerable inhibitory activity against cyclooxygenase (COX-1, COX-2). Continuous phytochemical study of the MeOH extract of this plant led to the isolation of ten flavonoids; sakuranetin (1), rhamnocitrin (2), 7-O-methylaromadendrin (3), naringenin (4), eriodictyol (5), aromadendrin (6), kaempferol (7), neosakuranin (8), sakuranin (9) and sakurenetin-5,4'-di-beta-D-glucopyranoside (10). Their structures were identified on the basis of their physicochemical and spectroscopic analyses. The isolated compounds, 1-10, were tested for their inhibitory activities against COX-1 and COX-2. Compound 7 was found to have potent inhibitory effect on COX-1 and a moderate effect on COX-2, meanwhile, compounds 1-6 showed moderate inhibition against COX-1 only. Moreover, compounds 5-8 exhibited suppressive effects on xanthine oxidase (XO). These results may explain, in part, the traditional uses of P. davidiana in ethnomedicine.
Anti-Inflammatory Agents, Non-Steroidal↗
Monoamine oxidase inhibitory coumarins from the aerial parts of Dictamnus albus.
The methanol extract from the aerial parts of Dictamnus albus was active in inhibiting monoamine oxidase (MAO) from the mouse brain. Activity-guided fractionation led to the isolation of four known coumarins, 7-(6'R-hydroxy-3', 7'-dimethyl-2'E, 7'-octadienyloxy) coumarin (1), auraptene (2), umbelliferone (3), and xanthotoxin (4), as active compounds along with an inactive alkaloid, skimmianine (5). Compounds 1 and 2 inhibited MAO activity in a concentration-dependent manner with IC50 values of 0.7 and 1.7 microM, respectively. Compounds 1 and 2 showed a slight and potently selective inhibitory effect against MAO-B (IC50 0.5 and 0.6 microM, respectively) compared to MAO-A (IC50 1.3 and 34.6 microM, respectively). According to kinetic analyses derived by Lineweaver-Burk reciprocal plots, compounds 1 and 2 exhibited a competitive inhibition to MAO-B.
Animals↗
Annomocherin, annonacin and annomontacin: a novel and two known bioactive mono-tetrahydrofuran annonaceous acetogenins from Annona cherimolia seeds.
A novel and two known bioactive mono-tetrahydrofuran (THF) annonaceous acetogenins, annomocherin (1), annonacin (2) and annomontacin (3), have been isolated from the fractionated ethanolic extracts of the seeds of Annona cherimolia, guided by the brine shrimp lethality test (BST). Their structures were elucidated on the basis of spectroscopic and chemical methods. All compounds have a relative stereochemistry of threo/trans/threo for the mono-THF ring with two flanking hydroxyls. Compound 1 has a double bond at C-23/24 of aliphatic chain. Compound 1 was isolated from natural sources for the first time, and was named annomocherin. Two known Compounds 2 and 3 which have never been isolated from this species before, were obtained. Compound 1 exhibited potent and selective cytotoxicities against the breast carcinoma (MCF-7) and kidney carcinoma (A-498) cell lines with 100 to 1,000 times the potency of adriamycin. In brine shrimp lethality test (BST), 1-3 exhibited cytotoxicity.
4-Butyrolactone↗
Antioxidative components from the aerial parts of Lactuca scariola L.
The antioxidant activity of Lactuca scariola (Compositae) was investigated by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) radical. The methanolic extract of the aerial parts of Lactuca scariola showed strong radical scavenging activity. The EtOAc soluble fraction exhibited a stronger activity than the others, and was purified by silica gel and Sephadex LH-20 column chromatography. Quercetin-3-O-beta-D-glucopyranoside, luteolin-7-O-beta-D-glucopyranoside, luteolin, quercetin and kaempferol, together with 1beta,13-dihydrolactucin were isolated from the EtOAc soluble fraction as active ingredients.
Antioxidants↗
A new coumarin from the stem of Angelica dahurica.
One new and three known coumarins were isolated from the CHCl3 soluble fraction of Angelica dahurica stem. On the basis of spectral data, the structures of the isolated compounds were determined to be scopoletin, angelol I, angelol H and 6-[(1S), 2(R)-2, 3-dihydroxy-1-methoxy-3-methylbutyl]-7-methoxycoumarin; the latter being isolated for the first time from a plant source.
Angelica↗
Thymol derivatives from Carpesium divaricatum.
Four thymol derivatives, 2,5-dimethoxythymol (1), 2-methoxythymol isobutyrate (2), 10-isobutyloxy-8,9-epoxythymolisobutyrate (3) and 10-(2-methylbutyloxy)-8,9-epoxythymolisobutyrate (4) were isolated from the aerial parts of Carpesium divaricatum. The structures were elucidated by high field 1D and 2D NMR techniques.
Asteraceae↗