ascorbic-acid and benzaldehyde

A headspace sampling-gas chromatography/mass spectrometry (HS-GC/MS) method using mild HS conditions (40 °C, 30 min) was established, validated in terms of specificity, linearity (1.75-87.65 ng mL

Topics: Artifacts; Ascorbic Acid; Benzaldehydes; Benzene; Benzoates; Benzoic Acid; Beverages; Copper; Ferrous Compounds; Gas Chromatography-Mass Spectrometry; Hot Temperature; Pyridoxine; Reproducibility of Results; Riboflavin; Solid Phase Microextraction

During sampling and analysis of alcohol-free beverages for food control purposes, a comparably high contamination of benzene (up to 4.6μg/L) has been detected in cherry-flavoured products, even when they were not preserved using benzoic acid (which is a known precursor of benzene formation). There has been some speculation in the literature that formation may occur from benzaldehyde, which is contained in natural and artificial cherry flavours. In this study, model experiments were able to confirm that benzaldehyde does indeed degrade to benzene under heating conditions, and especially in the presence of ascorbic acid. Analysis of a large collective of authentic beverages from the market (n=170) further confirmed that benzene content is significantly correlated to the presence of benzaldehyde (r=0.61, p<0.0001). In the case of cherry flavoured beverages, industrial best practices should include monitoring for benzene. Formulations containing either benzoic acid or benzaldehyde in combination with ascorbic acid should be avoided.

Topics: Ascorbic Acid; Benzaldehydes; Benzene; Benzoic Acid; Beverages; Flavoring Agents; Hot Temperature

Compounds 1 (N1-(3-ethynylphenyl)-6-methyl-N5-(3-(6-(methylamino)pyrimidin-4-yl)pyridin-2-yl) isoquinoline-1,5-diamine) and 2 (N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine; Erlotinib/Tarceva) are kinase inhibitors that contain a terminal phenyl acetylene moiety. When incubated in the presence of P450 and NADPH, the anticipated phenyl acetic acid metabolite was formed. When 10 mM of N-acetyl-l-cysteine was added to the incubation mixtures, the phenyl acetic acid product was reduced and at 25 mM or higher concentration of NAC, formation of the phenyl acetic acid was abolished. Instead, the phenyl acetylene moiety lost a carbon and formed a benzaldehyde product. Other oxidation products incorporating one or more equivalents of NAC were also observed. The identities of the metabolites were characterized by MS and NMR. Addition of deferoxamine or ascorbic acid diminished the formation of the NAC influenced products. Similar products were also observed when 1 or 2 were incubated in P450 reactions supplemented with GSH, in Fenton reactions supplemented with NAC or GSH, and in peroxidase reactions supplemented with NAC. We propose the thiols act as a pro-oxidant readily undergoing a one-electron oxidation to form thiyl radicals which in turn initiates the formation of other peroxy radicals that drive the reaction to the observed products. These in vitro findings suggest that one-electron oxidation of thiols may promote the cooxidation of xenobiotic substrates.

Topics: Acetylcysteine; Acetylene; Animals; Antioxidants; Ascorbic Acid; Benzaldehydes; Cattle; Chelating Agents; Cytochrome P-450 Enzyme System; Deferoxamine; Dogs; Glutathione; Humans; Male; Oxidation-Reduction; Rats; Rats, Sprague-Dawley