Showing papers on "Sodium dichromate published in 1984"

In vitro effects of N-acetylcysteine on the mutagenicity of direct-acting compounds and procarcinogens.

Abstract: N-Acetylcysteine (NAC), reduced (GSH) and oxidized (GSSG) glutathione were negative in the Ames test with 7 Salmonella strains, while L-cysteine was activated by rat liver S-9 fractions to metabolites mutagenic to strains TA102, TA97 and TA100. The mutagenic response in S. typhimurium strains (TA1535, TA98, TA100, TA102) and the levels of enzyme activities, responsible for NADP+ or GSSG reduction and for the utilization of NADPH or GSH in rat liver S-9 fractions, were investigated following in vitro preincubation of NAC with four direct-acting mutagens and six procarcinogens. Treatment with this nucleophilic and reducing compound resulted in a dose-related decrease of the direct mutagenicity of epichlorohydrin, hydrogen peroxide and, sharply, of 4-nitroquinolino-N-oxide and sodium dichromate. The mutagenicity of these compounds, both in the absence and in the presence of NAC, was decreased by rat liver S-9 fractions and to some extent by lung S-9 fractions. A diphasic effect was observed in the case of procarcinogens (cyclophosphamide, 2-aminofluorene, cigarette smoke condensate, Trp-P-2, aflatoxin B1 and benzo[a]pyrene), i.e., an enhancement of S-9 requiring mutagenicity at intermediate NAC doses, which could be ascribed to metabolic factors acting in vitro, and a loss of mutagenicity at high NAC doses, which could be ascribed to trapping of electrophilic metabolites. Out of the five S-9 enzyme activities under study, i.e., glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, malic enzyme, GSH peroxidase and GSSG reductase, only the last one showed significant changes following mutagen and/or NAC treatment.

Oxidation of Halides, Ethers, Acetals, Sulphides, and Some Nitrogen Containing Compounds

Abstract: The direct conversion of alkyl halides into the corresponding carbonyl compounds, despite its potential interest for organic synthesis, is seldomly referred to in the literature. Only few examples of the oxidation of benzylic halides with aqueous acidic chromic acid or with aqueous sodium dichromate and alkali hydroxides [1] under rather drastic conditions have been reported. A preparatively useful example is the oxidation of α-chlorohydrindene to a-hydrindanone in 50–60% yield by means of chromic acid in aqueous acetic acid at 40 °C [2]: Open image in new window