(S) -2-Hydroxy-3-phenylpropanoic acid

(S) -2-Hydroxy-3-phenylpropanoic acid (L- (−) -3-Phenyllactic acid) is a chiral aromatic compound involved in phenylalanine metabolism. It is likely produced from phenylpyruvate via lactate dehydrogenase. The D-form is derived from bacterial sources, while the L-form is endogenous. Phenyllactate levels are normally very low in blood or urine, but high levels indicate phenylketonuria (PKU) and hyperphenylalaninemia (HPA) . PKU is due to a deficiency of phenylalanine hydroxylase (PAH), causing phenylalanine to convert to phenylpyruvic acid rather than tyrosine.