hippuric acid
An acyl glycine produced by the conjugation of benzoic acid and glycine.
Some food with phenolic compounds such as tea and wine are converted into benzoic acid which is then converted into hippuric acid and excreted in the urine as a metabolite.
An increased content in urine may have antibacterial effects.
It is a uremic toxin.
The biosynthesis of hippuric acid takes place almost entirely in the liver, using both ATP and CoA. It is normally present in urine as a metabolite of dietary components.
Therefore, the analysis of hippuric acid in urine provides an diet and liver diagnostic test (hippuric acid test). It is a useful index of liver function, however, it gives erroneous results in the event of failure of renal excretory function.
(Causes that it is found in urine)
• quercetin: A natural phenolic compound, flavonoid (plant pigment) in food such as tea, wine, fruit juices, prunes, blueberries (e.g. black grape, strawberries, cranberries, red grape), beets, etc. It has antioxidant and anti-inflammatory effects.
• acetylsalicylic acid: Aspirin, a nonsteroidal antiinflammatory drug (NSAID), that reduces the signs and symptoms of inflammation, etc. It is changed to salicilyc acid, that is a typical reaction of hydrolysis of an active drug to an active metabolite.
• methenamine hippurate: Antibiotic oral agent, used to prevent urinary tract infections due to bacteria. The component is converted into formaldehyde in acidic urine, which has antibacterial activity.
• toluene: Occupational exposure to toluene. It is used as solvent in glues, paints, paint thinners, printing ink, rubber, etc. It is also contained in tobacco smoke. The exposure occurs mainly by breathing the gas and also through the skin in contact of the liquid.
After ingestion of quercetin, administration of acetylsalicylic acid or methenamine hippurate, or exposure to toluene, large quantities of hippuric acid are extracted in the urine and quantities of it are correlated to the quantities of ingestion or administration or exposure.
Cranberry juice increases the acidity of the urine slightly and increases the hippuric acid content of the urine.
The acidity is also important as well as the concentration for hippuric acid to act bacteriostatically in the urinary tract.