Hippurate
| Metabolite Information | Value |
|---|---|
| HMDB ID | HMDB0000714 |
| KEGG ID | C01586 |
| IUPAC name | 2-(phenylformamido)acetic acid |
| Structure |  |
| SMILES | OC(=O)CNC(=O)C1=CC=CC=C1 |
| Average molecular weight | 179.1727 |
Hippurate (hippuric acid) is an acyl glycine formed by the conjugation of benzoic acid and glycine. Glycine acyltransferase catalyses the transfer of benzoate from benzoyl-CoA to glycine. The resulting hippurate is excreted via urine.
Human diet contains benzoate in variable amounts. Sodium benzoate is a common preservative that is particularly effective in acidic foods, so can be found in soft drinks, fruit juices, salad dressings, pickled foods etc. Benzoate can also be derived from dietary sources of polyphenolic compounds, including some fruits, vegetables, tea, and coffee [ref].
It has been estimated that 83-100% of ingested benzoate is excreted as hippurate, and that this varies by species. The observed differences have been attributed to variations in glycine and glucuronic acid conjugation capacity of the liver and kidneys, and the rate of glycine mobilisation [ref].
Animal studies have shown hippurate increases with age during the early stages of life. In male Wistar-derived rats, urine samples showed low and variable hippurate levels at four weeks of age, then an increase and eventual stabilisation beginning at approximately 8 weeks of age [ref]. Maturation of the gut microbiome and adaptation to an adult diet are believed to contribute to this change.
Benzoate, and subsequent hippurate, can be derived from a number of dietary metabolites including phenylalanine [ref], quinate [ref], shikimate [ref][ref][ref], and polyphenolic compounds such as chlorogenate and (+)-catechin.