phenylpyruvic acid

Phenylpyruvic acid (3-Phenylpyruvic acid) is a keto-acid that is an intermediate or catabolic byproduct of phenylalanine metabolism. It has a slight honey-like odor. Levels of phenylpyruvate are normally very low in blood or urine. High levels of phenylpyruvic acid can be found in the urine of individuals with phenylketonuria (PKU), an inborn error of metabolism.

4-Hydroxyphenylpyruvic acid is an enzyme inhibitor.4-Hydroxyphenylpyruvic acid (4-HPPA) is a keto acid that is involved in the tyrosine catabolism pathway. It is a product of the enzyme (R)-4-hydroxyphenyllactate dehydrogenase (EC 1.1.1.222) and is formed during tyrosine metabolism. The conversion from tyrosine to 4-HPPA is catalyzed by tyrosine aminotransferase. Additionally, 4-HPPA can be converted to homogentisic acid which is one of the precursors to ochronotic pigment. The enzyme 4-hydroxyphenylpyruvic acid dioxygenase (HPD) catalyzes the reaction that converts 4-hydroxyphenylpyruvic acid to homogentisic acid. A deficiency in the catalytic activity of HPD is known to lead to tyrosinemia type III, an autosomal recessive disorder characterized by elevated levels of blood tyrosine and massive excretion of tyrosine derivatives into urine. It has been shown that hawkinsinuria, an autosomal dominant disorder characterized by the excretion of 'hawkinsin,' may also be a result of HPD deficiency . Moreover, 4-hydroxyphenylpyruvic acid is also found to be associated in phenylketonuria, which is also an inborn error of metabolism. There are two isomers of HPPA, specifically 4HPPA and 3HPPA, of which 4HPPA is the most common.

Sodium phenylpyruvate (Phenylpyruvic acid, sodium salt) is a substrate for phenylpyruvate decarboxylase and phenylpyruvate tautomerase.

(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.