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Oxidations of Aldehydes and Ketones to Carboxylic Acids01:15

Oxidations of Aldehydes and Ketones to Carboxylic Acids

Oxidation of aldehydes and ketones results in the formation of carboxylic acids. Aldehydes, bearing hydrogen next to the carbonyl group, are easily oxidized compared to ketones. This is because an aldehydic proton can easily be abstracted during oxidation.
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When toxic substances penetrate the human body, they disseminate to various tissues, undergoing metabolic changes. This process yields reactive metabolites that may covalently bind with specific target molecules, resulting in toxicity.
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Related Experiment Video

Updated: Jul 23, 2026

A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s
07:38

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All oxygens in nucleic acids react with carcinogenic ethylating agents.

B Singer

    Nature
    |November 25, 1976
    PubMed
    Summary

    Ethylnitrosourea and ethylnitrosoguanidine primarily modify nucleic acid oxygens. Reactivity differs between single-stranded RNA/DNA and double-stranded DNA, with O2-alkylpyrimidines showing a labile glycosidic bond.

    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Chemical Carcinogenesis

    Background:

    • Ethylnitrosourea (ENU) and ethylnitrosoguanidine (ENNG) are alkylating agents known to modify nucleic acids.
    • Understanding the specific sites and relative reactivity of these modifications is crucial for assessing mutagenic and carcinogenic potential.

    Purpose of the Study:

    • To investigate the preferential sites of modification on nucleic acids by ENU and ENNG.
    • To compare the oxygen reactivity patterns in single-stranded RNA, single-stranded DNA, and double-stranded DNA.

    Main Methods:

    • Chemical modification of nucleic acids (RNA and DNA) using ENU and ENNG.
    • Analysis of modification sites, focusing on oxygen atoms (excluding ribose and phosphate).

    Main Results:

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    • Over 80% of ENU and ENNG modifications occur on oxygen atoms of nucleic acids.
    • In single-stranded RNA, oxygen reactivity follows the order: O2(Cytosine) > O2(Uracil) > O6(Guanine) > O4(Uracil).
    • In double-stranded DNA, the order is: O2(Thymine) = O6(Guanine) > O4(Thymine) > O2(Cytosine), with single-stranded DNA showing similar reactivity to RNA.
    • The glycosidic bond in O2-alkylated pyrimidines is destabilized.

    Conclusions:

    • Oxygen atoms are the primary targets for ENU and ENNG alkylation in nucleic acids.
    • Distinct reactivity patterns exist for oxygen modifications in different nucleic acid structures (ssRNA, ssDNA, dsDNA).
    • The observed lability of the glycosidic bond in O2-alkylated pyrimidines suggests a potential mechanism for DNA damage and mutation.