Phenylpyruvic acid may be a direct precursor of mandelic acid without intermediate transamination of phenylalanine
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Updated: Jul 29, 2026

A Strategy for Sensitive, Large Scale Quantitative Metabolomics
Published on: May 27, 2014
B L Godwin1, C R Ruthven, M Sandler
1Department of Chemical Pathology, Queen Charlotte's and Chelsea Hospital, London, U.K.
Abstract:
A series of compounds related to phenylalanine was administered to rats. Output of mandelic acid, a major but unexplained metabolite in phenylketonuria, was increased after the administration of phenylethanolamine or phenylpyruvic acid, whereas phenylethylamine or phenylalanine increased its excretion only marginally. Phenylacetic acid, previously suggested as a possible precursor in man, was almost without effect. It seems likely that mandelic acid can be formed from phenylpyruvic acid directly, without intermediate transamination to phenylalanine.
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