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Updated: May 5, 2026
11:56
A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 12, 2014
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Fat transforms ascorbic acid from inhibiting to promoting acid-catalysed N-nitrosation
E Combet1, S Paterson, K Iijima
1Division of Cardiovascular and Medical Sciences, Western Infirmary, University of Glasgow, Glasgow, Scotland.
Gut
|September 6, 2007
Summary
Ascorbic acid inhibits stomach acid nitrosation, reducing carcinogen formation. However, lipids reverse this effect, promoting nitrosamine production by regenerating nitrosating species.
Area of Science:
- Gastroenterology
- Chemical carcinogenesis
- Nutritional biochemistry
Background:
- The proximal stomach is a key site for acid nitrosation, linked to metaplasia and adenocarcinoma.
- Salivary nitrite can form pre-carcinogens like N-nitroso compounds in the acidic stomach.
Purpose of the Study:
- To investigate how lipids and ascorbic acid influence nitrosative chemistry in a simulated proximal stomach environment.
- To understand the role of these compounds in the formation of potentially carcinogenic N-nitroso compounds.
Main Methods:
- In vitro modeling of proximal stomach conditions to study nitrosation of secondary amines.
- Quantification of N-nitrosamines using gas chromatography-ion-trap tandem mass spectrometry.
- Amperometric measurement of nitric oxide and oxygen levels.
Main Results:
- Ascorbic acid inhibited nitrosation and N-nitrosamine formation in the absence of lipids.
- Lipids reversed ascorbic acid's effect, significantly increasing N-nitrosamine formation (e.g., N-nitrosodimethylamine by 8-fold).
Conclusions:
- Lipids transform ascorbic acid from an inhibitor to a promoter of acid nitrosation.
- This switch is potentially due to nitric oxide, generated by ascorbic acid, regenerating nitrosating species in the lipid phase.
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