Nitrite sources and nitrosamine formation in vitro and in vivo

Walters, C. L.; Carr, F P A; Dyke, C S; Saxby, M.J.; Smith, Penny; Walker, Ronald W.

doi:10.1016/0015-6264(79)90006-3

Cited by 58 publications

(20 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The generation of N-nitroso-compounds from secondary amines (1) or from amides (2) and nitrite (3,4) under acidic conditions could represent an important mechanism for the in vivo formation of carcinogens in the stomach. The nitrosation of primary aliphatic amines (5) is known to the chemist as a deamination reaction because it leads to chemically unstable products which spontaneously hydrolyze to alcohols.…”

Section: Introductionmentioning

confidence: 99%

Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite

Huber

Lutz

1984

Carcinogenesis

View full text Add to dashboard Cite

'To whom reprint requests should be sent Young adult male Sprague-Dawley rats were given 30 /xmol/kg body weight [ 14 C]methylamine hydrochloride and 700 /anol/ kg body weight sodium nitrite by oral gavage. DNA isolated from the stomach and from the first 15 cm of the small intestine was methylated, containing 7-methylguanine (7mG) at a level of one 7mG molecule per 5xlO 6 and lxlO 7 nucleotides, respectively. No 7mG was found in the liver at a limit of detection of one 7mG molecule per 2x10° nucleotides. In a second experiment, the excised stomachs were incubated with deoxyribonudease before the isolation of the DNA in order to degrade DNA in the lumen and in the uppermost lining cells. This treatment resulted in a 30% decrease in the yield of DNA and a 90% reduction in the level of 7mG formation. The results show that nitrosation of a primary alkylamine yields a precursor of an alkylating agent which has a long enough lifetime to diffuse towards and react with intracellular DNA. A correlation of DNA methylation in the stomach with the corresponding tumor formation by the methylating carcinogen N-methyl-N' -nitro-N-nitroso-guanidine was used to estimate the role of DNA damage resulting from endogenous nitrosation of dietary methylamine in man. It was concluded that the risk resulting from this single amine must be negligible but that a similar evaluation of other primary amines is required before the over-all role of primary amine nitrosation in the etiology of human gastric cancer can be assessed.

show abstract

Section: Introductionmentioning

confidence: 99%

Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite

Huber

Lutz

1984

Carcinogenesis

View full text Add to dashboard Cite

show abstract

“…According to Spiegelhalder et al [1976], nitrate intakes of less than about 54 mg as N 0 3~ did not result in increases in sali vary nitrate or nitrite; above that amount, approximately 25% of the nitrate ingested is located in the saliva and of that increment about one-fifth is reduced to nitrite. Walters et al, [1979a] reported an increase of 98 mg 1_1 sodium nitrite per 100 mg nitrate (as K N03) in gested in salad-type meals. Smaller secondary peaks of nitrate and nitrite were noted by Spiegelhalder et al [1976] in the salivas of volunteers ingesting nitrate.…”

Section: Nitrite Derived From Ingested Nitratementioning

confidence: 99%

The Exposure of Humans to Nitrite

Walters¹

1980

Oncology

Self Cite

View full text Add to dashboard Cite

Although nitrate is more abundant than nitrite in food and the environment in general, it requires reduction by, for instance, bacterial or plant enzymes before it is involved in the nitrosation of amines or amides. Part of the exposure of humans to nitrite arises from its use as a food additive where it performs a very useful function in protecting the consumer from pathogenic micro-organisms such as Clostridium botulinum. Some untreated foodstuffs, such as potatoes, tomatoes and beets, also contain low levels of nitrite. Nevertheless, the main source of human contact is that produced in vivo from nitrate ingested in foods in general and in vegetables in particular. Nitrate also occurs widely in drinking water supplies and this source can also contribute in some measure to human exposure. As yet, it is not possible to compute with accuracy the contribution from any endogenous synthesis within the gastrointestinal tract. Since the rate of nitrosation of an amine is dependent on the nitrite concentration to a power of greater than unity, it is probable that nitrite ingested in one application over a short period will be more active in the synthesis of N-nitroso compounds than a continuous supply at lower concentrations over long periods.

show abstract

“…Thus, it seems that oral bacteria are one of the main sources of reduced nitrite in saliva. [1213] The concentration of nitrite in saliva is dependent on the concentration of nitrate. The nitrite and NO formed in the human oral cavity can be oxidized by molecular oxygen and by salivary peroxidase.…”

Section: Discussionmentioning

confidence: 99%

Estimation and correlative study of salivary nitrate and nitrite in tobacco related oral squamous carcinoma and submucous fibrosis

Shende¹,

Akarte

2013

J Oral Maxillofac Pathol

View full text Add to dashboard Cite

Oral cancer is one of the ten leading cancers of the world. In India, it is one of the common cancers and is an important public health problem. Tobacco plays significant role in etiology of oral squamous carcinoma. Tobacco which is chewed or smoked contains many alkaloids which are known carcinogens. Oral submucous fibrosis (OSMF) is a disease of the Indian subcontinent, which through immigration has a worldwide distribution. Betel nut chewing plays significant role in etiology of OSMF. The nut alkaloids have been shown experimentally to result in stimulation of collagen synthesis by fibroblasts in vitro, which can induce precancerous conditions.Materials and Methods:The present study was undertaken to detect nitrate and nitrite factor in saliva of cases with oral carcinoma, OSMF and normal individuals without any habits and to determine whether increased salivary nitrate and nitrite level is significant in oral carcinoma and submucous fibrosis using biochemical parameters.Conclusion:We conclude that the major inducer of oral squamous cell carcinoma (OSCC) is exposure to tobacco. Recent studies have demonstrated that oxidative and nitrosative stress contributes to the development of oral carcinogenesis through deoxyribonucleic acid (DNA) damage. Salivary composition of OSCC patients is substantially altered with respect to free radical-involved mechanisms.

show abstract

Nitrite sources and nitrosamine formation in vitro and in vivo

Cited by 58 publications

References 22 publications

Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite

Methylation of DNA in stomach and small intestine of rats after oral administration of methylamine and nitrite

The Exposure of Humans to Nitrite

Estimation and correlative study of salivary nitrate and nitrite in tobacco related oral squamous carcinoma and submucous fibrosis

Contact Info

Product

Resources

About