Secondary ion mass spectrometry of some promazines and photochemistry of chlorpromazine in glycerol

Evidence for a mechanism that involves secondary electron capture in the liquid secondary ionization mass spectrometry beam-induced dehalogenation of organic compounds

The effect of the analyte electron affinity on the liquid secondary ionization mass spectrometry beam-induced dehalogenation of simple bromoaromatic compounds in a glycerol matrix was investigated. The results show a definite trend of decreasing dehalogenation with increasing analyte electron affinity. At high analyte electron affinity (≥ 1.0 eV), no dehalogenation was observed. These results are consistent with electrochemical and pulse radiolysis studies where one electron reduction was shown to be responsible for dehalogenation. A chloroaromatic compound with high electron affinity, 4-(4-chloro-benzoyl)pyridine, exhibited reduction by hydrogen addition but not dehalogenation. The radiation chemistry of alcohols was used to elaborate a scheme of the reactive species generated in the glycerol matrix by kiloelectronvolt particle bombardment. The possible role of those species in reduction processes such as dehalogenation was evaluated. The observation that dehalogenation decreases with analyte electron affinity is mechanistically consistent with the proposition that secondary electron production is an intrinsic part of the bombardment process.

Synthesis and characterization of iodixanol

Iodixanol (Visipaque) is a new nonionic roentgen contrast medium intended for general use. Visipaque is a pharmaceutical formulation of iodixanol which is isotonic and iso-osmotic with blood. Two synthetic routes from 5-nitro-isophthalic acid to iodixanol are described. The chemical structure is confirmed spectroscopical data ((1)H-NMR, (13)C-NMR, FAB-MS, UV, IR and Raman). Chromotographic characteristics are related to the isomerism of iodixanol.

Toxic effects of the photoproducts of chlorpromazine on cultured hepatocytes

The photodegradation of chlorpromazine, a drug frequently used in psychotherapy, was examined under different sets of experimental conditions. A primary culture of rat hepatocytes was used to evaluate the possible hepatotoxicity of the chlorpromazine photoproducts, keeping in mind the following criteria: leakage of cytosolic enzymes; attachment index to culture plates, and albumin synthesis. Cells exposed to concentrations greater than 10(-4) M of the photomixtures showed extensive leakage of GOT and GPT into the culture medium and, at the same time, the cell attachment was seriously impaired. A concentration of 10(-7) M of the photoproducts proved capable of inhibiting the synthesis of albumin (20%). Photoproducts obtained after aerobic irradiations were as toxic for hepatocytes as those found in anaerobic conditions. The implications of our results in connection with the relevance of oxygen-dependent photoreactions of chlorpromazine to its phototoxicity, and the possible appearance of hepatic alterations in patients treated with the drug after exposure to the sunlight, are discussed.

Biomolecular photoalterations mediated by phenothiazine derivatives

This survey focuses on recent developments in the field of the ultraviolet photochemistry and photobiology of phenothiazine derivatives. One of the major alterations introduced by this kind of photosensitized reaction is a covalent addition of the photosensitizer or one of its photoproducts onto the macromolecular target. This reaction has been observed with soluble and membrane proteins, lipids and DNA. In the latter case, the addition occurs at the level of guanine residues and leads to inhibition of DNA replication.

Induction of breaks in deoxyribonucleic acid by photoexcited promazine derivatives

Near-u.v. photoexcited promazine and three of its derivatives are shown to induce single-strand breaks in phi X174-DNA replicative form. The mechanisms of this DNA breakage depend upon the various photochemical properties of the promazine derivatives. Chlorpromazine is shown to act predominantly via the photodechlorination reaction both in aerobic and anaerobic conditions. The three other promazine derivatives (promazine, trifluopromazine and methoxypromazine) display two mechanisms for DNA breakage. One of them occurs through the cation radical, which is formed during near-u.v. irradiation of promazine derivatives. The second mechanism is demonstrated to act via an hydroxyl radical-dependent pathway. Acepromazine is without photoactivated action. EPR-spin-trapping studies of irradiated mixtures, containing the drugs and 5,5-dimethyl-1-pyrroline-N-oxide (as spin trap), suggest the production of superoxide radical by photoexcited promazines. When DNA is present in the irradiation mixture, this superoxide radical is converted into hydroxyl radical probably via a Haber Weiss-type reaction, catalysed by DNA-iron complexes.

On the influence of hydrophobicity in the SIMS spectra of amino acids in glycerol matrix

Mass spectrometry is becoming an important method in structure determination of biopolymers. Determination of the nature and the number of the various monomers is an important information for the elucidation of fragmentation patterns. We present here a matrix designed to allow both identification and semi-quantitative measurement of amino acids residues in peptides.