Gentisic acid is a

dihydroxybenzoic acid Dihydroxybenzoic acids (DHBA) are a type of phenolic acids. There are six main compounds, having all the same molecular formula C7H6O4. Those are: * 2,3-Dihydroxybenzoic acid (2-Pyrocatechuic acid or hypogallic acid) * 2,4-Dihydroxybenzoic acid ...

. It is a derivative of

benzoic acid Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, wh ...

and a minor (1%) product of the metabolic break down of

aspirin Aspirin, also known as acetylsalicylic acid (ASA), is a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and/or inflammation, and as an antithrombotic. Specific inflammatory conditions which aspirin is used to treat inc ...

, excreted by the kidneys. It is also found in the African tree ''

Alchornea cordifolia ''Alchornea cordifolia'' is a shrub or small tree distributed throughout tropical Africa, it can grow up to 8 metres tall. The plant is used in traditional African medicine. Common name is the Christmas bush. Chemical constituents The leaves, ...

'' and in

wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...

Production

Gentisic acid is produced by carboxylation of

hydroquinone Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a ''para'' ...

.Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. . :C₆H₄(OH)₂ + CO₂ → C₆H₃(CO₂H)(OH)₂ This conversion is an example of a

Kolbe–Schmitt reaction The Kolbe–Schmitt reaction or Kolbe process (named after Hermann Kolbe and Rudolf Schmitt) is a carboxylation chemical reaction that proceeds by heating sodium phenoxide (the sodium salt of phenol) with carbon dioxide under pressure (100 at ...

. Alternatively the compound can be synthesized from

salicylic acid Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substance ...

via

Elbs persulfate oxidation The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form ''para''-diphenols. The reaction is generally performed in water at room temperatures or below, using equimolar quantities of reagents. ...

Reactions

In the presence of the enzyme gentisate 1,2-dioxygenase, gentisic acid reacts with

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

to give maleylpyruvate: :2,5-dihydroxybenzoate + O₂

\rightleftharpoons

maleylpyruvate

Applications

As a

, gentisic acid is readily oxidised and is used as an

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

excipient An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred ...

in some

pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...

preparations. In the laboratory, it is used as a sample matrix in

matrix-assisted laser desorption/ionization In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of ...

(MALDI)

mass spectrometry Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is use ...

, and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI.

References

{{DEFAULTSORT:Gentisic Acid Hydroquinones Salicylic acids Dihydroxybenzoic acids Phenolic human metabolites Human drug metabolites