ascorbic-acid and dimethylamine

Trimethylamine oxide (TMAO) in squid is demethylated to dimethylamine (DMA) and formaldehyde (FA) during storage and processing. This study examined the effects of thermal processing and various chemical substances on FA and DMA formation in squid.. The thermal conversion of TMAO was assessed by analysing four squid and four gadoid fish species, which revealed that FA, DMA and trimethylamine (TMA) were gradually produced in squid, whereas TMA increased and FA decreased in gadoid fish. A significant increase in both FA and DMA levels was observed in the supernatant of jumbo squid with increased heating temperature and extended heating time at pH 6-7. Ferrous chloride combined with cysteine and/or ascorbate had a significantly positive effect on FA formation in the heated supernatant of jumbo squid. No significant difference was observed in the levels of Cu and Fe in squid and gadoid fish. The capability of Fe(2+) to promote the formation of FA and DMA was not completely attributable to its reducing power in squid.. Non-enzymatic decomposition of TMAO was a key pathway during the thermal processing of jumbo squid, and Fe(2+) was a crucial activator in the formation of FA and DMA.

Topics: Animals; Ascorbic Acid; Cysteine; Decapodiformes; Dimethylamines; Ferrous Compounds; Fishes; Food Handling; Formaldehyde; Hot Temperature; Humans; Hydrogen-Ion Concentration; Iron; Methylamines; Seafood

In a series of experiments on formation of N-nitrosamines from precursors in the gastric juice, we investigated individual nitrosation capacity and the influence of inhibitors on this process. In the presence of a molar ratio of 2:1 ascorbic acid:NaNO2, we found increased nitrosamine formation in 34% of gastric juice samples. Ferulic acid and caffeic acid generally suppressed nitrosation at high concentrations and stimulated it at low concentrations. The concentration at which the transition from a stimulating to an inhibitory effect occurs depends on individual differences in the gastric juice.

Topics: Antioxidants; Ascorbic Acid; Dimethylamines; Dimethylnitrosamine; Gastric Juice; Humans; Nitrosamines

The levels of trimethylamine N-oxide (TMAO) in the New Zealand (Nototodarus sloani) species of squid extracts were extremely high (above 9200 ppm). When the extracts were incubated for 2 days at 25 degrees C, approximately 60% TMAO was converted to trimethylamine (TMA) and dimethylamine (DMA). This conversion was very low or negligible at 4 degrees C, but was potentiated by the presence of ferrous sulphate (0.014 M) and ascorbate (0.014 M). Citrobacter freundii and Aeromonas hydrophilia were isolated from the extracts. Cultures of these two micro-organisms and of Escherichia coli were active in catalysing the conversion of TMAO to TMA and DMA either in extract or in aqueous solution. Chloramphenicol (0.416 mg/ml) completely inhibited the growth of these micro-organisms and also effectively blocked the conversion of endogenous TMAO to TMA in the extracts. The present findings suggest that gastro-intestinal flora and dietary ferrous salts and ascorbate may play important roles in the conversion of TMAO to TMA and DMA in man following the ingestion of squid and other TMAO-containing seafoods.

Topics: Animals; Ascorbic Acid; Bacteria; Chloramphenicol; Decapodiformes; Dimethylamines; Drug Synergism; Ferrous Compounds; Methylamines

It is known that nitrates, nitrites and dimethylamine may react in the gastro-intestinal tract synthesizing the powerful hepatotoxic and carcinogenic dimethylnitrosamine. The purpose of this study was to investigate hepatotoxicity due to the daily intake of nitrates and nitrites administered to rats during 14 weeks together with dimethylamine in drinking water, and to evaluate the protecting effect of ascorbic acid against the hepatotoxicity of the presumably endogenous formed dimethylnitrosamine. The toxicity criteria studied were weight of liver (absolute and relative), free and total bilirubin, alkaline phosphatase and pyruvic glutamic transaminase, all in the form of serum, and histopathologic tests of the liver. The results gave evidence of hepatotoxicity induced by the intake of nitrate, nitrite and dimethylamine all together, and not through the only intake of nitrate or nitrite or of amine. Daily doses of ascorbic acid [(211 +/- 40) and (18 +/- 4) mg/kg] seemed to hinder hepatotoxicity according to the criteria under investigation.

Topics: Alanine Transaminase; Alkaline Phosphatase; Animals; Ascorbic Acid; Bilirubin; Body Weight; Chemical and Drug Induced Liver Injury; Diet; Dimethylamines; Female; Liver; Nitrates; Organ Size; Rats; Rats, Inbred Strains