Lipid peroxidation in human breast cancer cells in response to gamma-linolenic acid and iron.

Lipid peroxidation in human breast cancer (ZR-75-1) cells and cancer cell killing were confirmed by using ultraviolet (UV)-spectrophotometry and mass spectrometry (MS). ZR-75-1 cells and human normal fibroblast CCD-41-SK (41Sk) cells were cultured with gamma-linolenic acid (GLA) and ferrous iron Fe (II) combinations. Formation of lipid peroxide and cytotoxic effect were highest in ZR-75-1 cells treated with GLA + Fe (II), though 41Sk cells showed little evidence of either lipid peroxidation or cytotoxity. These results indicate a cancer-cell-specific lipid peroxidation mechanism in association with the selective cancer cell killing effect in response to GLA.

Mechanism of lipid peroxidation in cancer cells in response to gamma-linolenic acid (GLA) analyzed by GC-MS(I): Conjugated dienes with peroxyl (or hydroperoxyl) groups and cell-killing effects.

We have investigated the nature of lipid peroxidation occurring in association with cancer-killing produced by gamma-linolenic acid (GLA) and iron (Fe) in cultured human breast cancer cells (ZR-75-1: ZR). UV-spectrophotometry, high performance liquid chromatography (HPLC) and gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS) have been used to analyze lipid peroxides and their derivatives. Formation of conjugated dienes (CD), the conversion of triphenylphosphine (TPP) to its oxide (TPPO), and the simultaneous production of hydroxy polyunsaturated fatty acids (PUFA-OHs) from these corresponding PUFAs hydroperoxides (PUFA-OOHs) were analyzed in the total lipid extract of ZR cells and of normal human skin fibroblasts (CCD-41Sk:Sk). Fe enhanced the formation of both the CD and TPPO and increased the percentage of dead cells, while vitamin E inhibited these effects. Neither of these events was observed at any significant level in Sk cells. Identity of PUFA-OHs was confirmed by determining the regional positions of the hydroxyl group by GC-MS analysis of hydrogenated methyl ester tert-butyldimethylsilyl ether alcohol derivatives (Me-H2-PUFA-O-TBDMS). The regional isomers identified were 15-, 12- and 8-OH 20 carbon and 13-OH 18 carbon fatty acid derivatives. These results suggest that the increased formation of conjugated dienes and/or hydroperoxyl (or peroxyl) groups in PUFA molecules is relevant to the cancer cell-killing effect of GLA+Fe.

Determination of polycyclic aromatic compounds by high-performance liquid chromatography with simultaneous mass spectrometry and ultraviolet diode array detection.

A major problem in the determination of polycyclic aromatic compounds (PACs) in environmental samples is the extreme complexity of the extracts, even after extensive fractionation. The combination of high-performance liquid chromatography (HPLC) with simultaneous mass spectrometry (MS) and ultraviolet diode array detection (DAD) is a powerful tool for the identification and quantitation of such species with a high degree of confidence. HPLC allows the selective separation of a wide variety of PACs, including thermally labile and high molecular weight compounds. Electron ionization MS with the moving belt interface provides high sensitivity and selectivity, as well as structural information such as molecular weight, functional groups, and elemental composition. The diode array detector helps to differentiate isomeric structures and confirm compound identity.

Liquid chromatographic determination of domoic acid in shellfish products using the paralytic shellfish poison extraction procedure of the association of official analytical chemists.

Domoic acid, the recently discovered toxic substance found in contaminated mussels from an area in eastern Prince Edward Island (Canada) was extracted from mussel tissue using the procedure of the Association of Official Analytical Chemists for paralytic shellfish poisons. This involved a 5-min boiling of the sample with 0.1 M hydrochloric acid then cooling and centrifuging. An aliquot of the supernatant was diluted ten to one-hundred times with water, filtered and analysed by reversed-phase liquid chromatography with a mobile phase consisting of acetonitrile-water (12:88) at pH 2.5 and an absorption wavelength of 242 nm. The detection limit was about 0.5 mg/kg domoic acid in seafood samples. The technique was successfully applied to a variety of commercially purchased shellfish and shellfish products.

Use of a moving-belt interface for on-line high-performance liquid chromatography/mass spectrometry characterization of polycyclic aromatic compounds of molecular weight up to 580 Da in environmental samples.

The applicability of the moving belt high-performance liquid chromatography/mass spectrometry (HPLC/MS) interface to the analysis of high molecular weight polycyclic aromatic compounds (PACs) in a complex sample derived from coal tar is investigated. This interface provides good preservation of chromatographic integrity and useful electron ionization spectra of thermally stable PACs of low to moderate volatility up to molecular masses of at least 580 Da. It is concluded that this HPLC/MS technique will be useful in the analysis of such complex samples, provided a large enough suite of standard compounds can be made available.

C60 and C70 fullerene isomers generated in flames. Detection and verification by liquid chromatography/mass spectrometry analyses.

Fullerenes C60 and C70, generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having fullerene-like characteristics. Analysis of these additional compounds by high-performance liquid chromatography, coupled on-line with mass spectrometry has identified them as isomers of the C60 and C70 fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable fullerenes with a half-life of about 1 h in boiling toluene (111 degrees C). Isomers of C60 and C70 fullerenes previously have been studied theoretically, but not observed experimentally. The flame-generated material also contains C60O and C70O compounds, as well as C76 and higher carbon clusters.