| FEMA | N/A |
| CAS | 495-69-2 |
| EINECS | 207-806-3 |
| JECFA Food Flavoring | N/A |
| CoE Number | N/A |
| Organoleptic Notes |
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| Odor | N/A |
| Flavor | N/A |
| Material Notes | Hippuric acid (Gr. hippos, horse, ouron, urine) is a carboxylic acid found in the urine of horses and other herbivores. Hippuric acid crystallizes in rhombic prisms which are readily soluble in hot water, melt at 187 �C and decompose at about 240 �C. High concentrations of hippuric acid can also indicate a toluene intoxication. When many aromatic compounds such as benzoic acid and toluene are taken internally, they are converted to hippuric acid by reaction with the amino acid, glycine.; Hippuric acid is an acyl glycine formed by the conjugation of benzoic aicd with glycine. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction: acyl-CoA + glycine < -- > CoA + N-acylglycine. Hippuric acid is a normal component of urine and is typically increased with increased consumption of phenolic compounds (tea, wine, fruit juices). These phenols are converted to benzoic acid which is then converted to hippuric acid and excreted in the urine. Hippuric acid is the most frequently used biomarker in the biological monitoring of occupational exposure to toluene. This product of solvent biotransformation may be also found in the urine of individuals who have not been exposed to the solvent. A smaller fraction of the absorbed toluene is oxidized to aromatic compounds including ortho-cresol, which is not found significantly in the urine of nonexposed individuals. The concentration of hippuric acid in the urine of individuals exposed to a low toluene concentration does not differ from that of individuals not exposed to the solvent. This has led to the conclusion that hippuric acid should not be utilized in the biological monitoring of occupational exposure to low levels of toluene in the air.; Protein-bound organic acids such as hippuric acid are markedly accumulated in uremic plasma and produce defective protein binding of drugs. (PMID: 9120876, 8734460) |