MOLECULE

4-Hydroxybenzoic acid

4-Hydroxybenzoic acid, also known as p-hydroxybenzoate or 4-carboxyphenol, belongs to the class of organic compounds known as hydroxybenzoic acid derivatives. Hydroxybenzoic acid derivatives are compounds containing a hydroxybenzoic acid (or a derivative), which is a benzene ring bearing a carboxyl and a hydroxyl group. 4-Hydroxybenzoic acid is a neutral compound with a nutty and phenolic taste. 4-Hydroxybenzoic acid exists in all living species, from bacteria to humans. In humans, 4-hydroxybenzoic acid is involved in ubiquinone biosynthesis. 4-Hydroxybenzoic acid is found in highest concentrations in red huckleberries, corianders, and garden onions and in lower concentrations in soybeans, rye bread, and almonds. 4-hydroxybenzoic acid has also been detected in sour cherries, common beans, wild carrots, common oregano, and soft-necked garlics. This could make 4-hydroxybenzoic acid a potential biomarker for the consumption of these foods. 4-Hydroxybenzoic acid is also found in cannabis plants (PMID:6991645). 4-Hydroxybenzoic acid esters, known as parabens, are used as preservatives in cosmetics and some ophthalmic solutions. It is isomeric with 2-hydroxybenzoic acid, known as salicylic acid, a precursor to aspirin, and with 3-hydroxybenzoic acid. 4-Hydroxybenzoic acid has estrogenic activity and stimulated the growth of breast cancer cell lines (PMID: 16021681). It can be found in Escherichia coli as part of the ubiquinone pathway. In the first step of this pathway, chorismate lyase transforms chorismate into 4-hydroxybenzoate and pyruvate (PMID 1644758). In Pseudomonas sp., 4-hydroxybenzoate and chloride are produced when the enzyme 4-chlorobenzoate dehalogenase acts on the halide bond of 4-chlorobenzoate with H2O (PMID: 6497878).