2-Hydroxyphenylpyruvic acid

5-(p-Hydroxybenzal)hydantoin. An intimate mixture of 6.11 g. (0.050 mole) of / -hydroxybenzaldehyde (Note 1) and 5.5 g. (0.055 mole) of hydantoin (Note 2) is placed in a 250-ml. round-bottomed flask. Dry piperidine (10 ml.) is added, a reflux condenser protected by a calcium chloride tube is fitted to the flask, and the flask is immersed in an oil bath so that the level of the reaction mixture is the same as the oil level of the bath. The oil bath is heated slowly to 130° and is held at this temperature for 30 minutes foaming and gentle boiling occur. The reaction mixture is cooled, and 200 ml. of water at about 60° is added. The contents of the flask are stirred by means of a glass rod until a clear red solution is obtained (Note 3). Any traces of tarry material are removed by filtration. The solution is cooled to room temperature, transferred to an Erlenmeyer flask, and acidified by dropwise addition of 20 ml. of 12N hydrochloric acid. The mixture stands at room temperature a few hours, and then the yellow 

The liquid is transferred to a continuous extractor (Note 10) and extracted with ether until the supernatant layer of ether remains colorless (about 2 hours). The ethereal extract is discarded (Note 11). The aqueous solution is transferred to a 1-1. beaker and acidified by the cautious addition of 60 ml. of 121V hydrochloric acid (Note 12). The solution is returned to the extractor, which is attached to a tared round-bottomed flask. The solution is extracted with ether until no more -hydroxyphenylpyruvic acid is obtained (Note 13). The undried ether solution is evaporated to dryness on a boiling water bath to give crude p-hydroxy-phenylpyruvic acid as a pale-yellow crystalline mass. The mass is broken up with a spatula, and the flask is kept over potassium hydroxide in a vacuum desiccator until its weight is constant. The yield of crude acid is 6.9-7.2 g. (92-96%). It melts at 210— 215° (dec.) (Note 14). 

Twelve milliliters of water for each gram of the crude acid 

The -hydroxybenzaldehyde used was a commercial product (practical grade) melting at 114-117°. 

Hydantoin can be prepared in a variety of ways, notably from glycine2 or ethyl aminoacetate8 and potassium cyanate. The checkers used Eastman Kodak white label hydantoin. 

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The liver is also the principal metabolic center for hydrophobic amino acids, and hence changes in plasma concentrations or metabolism of these molecules is a good measure of the functional capacity of the liver. Two of the commonly used aromatic amino acids are phenylalanine and tyrosine, which are primarily metabolized by cytosolic enzymes in the liver [1,114-117]. Hydroxylation of phenylalanine to tyrosine by phenylalanine hydroxylase is very efficient by the liver first pass effect. In normal functioning liver, conversion of tyrosine to 4-hy-droxyphenylpyruvate by tyrosine transaminase and subsequent biotransformation to homogentisic acidby 4-hydroxyphenylpyruvic acid dioxygenase liberates CO2 from the C-1 position of the parent amino acid (Fig. 5) [1,118]. Thus, the C-1 position of phenylalanine or tyrosine is typically labeled with and the expired C02 is proportional to the metabolic activity of liver cytosolic enzymes, which corresponds to functional hepatic reserve. Oral or intravenous administration of the amino acids is possible [115]. This method is amenable to the continuous hepatic function measurement approach by monitoring changes in the spectral properties of tyrosine pre- and post-administration of the marker. 

In the hydrolysate of toxic components in the venom of bird-catching spiders (suborder Orthognatha, family Aviculariidae, subfamilies Grammostolinae and Theraphosinae), di-aminopropane, spermine, 4-hydroxyphenylpyruvic acid, 4-hydroxybenzoic acid, 4-hydroxy-phenylacetic acid, and 4-hydroxyphenyllactic acid have been identified. Separation and structure elucidation of the individual components of the original extract were not performed (35.36). 

Denoya, C.D., D.D. Skinner, and M.R. Morgenstern. 1994. A Streptomyces avermitilis gene encoding a 4-hydroxyphenylpyruvic acid dioxygenase-like protein that directs the production of homogentisic acid and an ochronotic pigment in... 

An enzyme that synthesises norlaudanosoline (25) has been isolated, and purified, from several plant species which normally produce isoquinoline alkaloids. Substrates for the enzyme were dopamine (21) and, most surprisingly, 3,4-dihydroxyphenylacet-aldehyde (23), and not 3,4-dihydroxyphenylpyruvic acid (22). 4-Hydroxyphenylacetaldehyde was a substrate for the enzyme but not 4-hydroxyphenylpyruvic acid or phenylpyruvic acid. The product of the clearly enzyme-catalysed reaction between (21) and (23) was norlaudanosoline (25) [predominantly the (S)-isomer]. No doubt... 

Fig. (13). Dimerisation of 4-hydroxyphenylpyruvic acid in concentrated hydrochloric acid.

The migration of alkyl substituents during the hydroxylation of 4-hydroxyphenylpyruvic acid (25) and 4-fluorophenylpyruvic acid (27) (Figure 8) provides another example of the NIH Shift and was formerly thought to be a unique phenomenon. It is in a sense atypical since a decarboxylation accompanies the hydroxylation and side chain migration. 

Reticuline.—A biosynthetic study of the important benzylisoquinoline reticuline (41), published in preliminary form/ has appeared in full/ Important new information is that 4-hydroxyphenylpyruvic acid (37) and 3,4-dihydroxyphenyl-pyruvic acid (38) are incorporated, like tyrosine, into both C6-C2 units of recticuline (41), in contrast to the transamination product of (38), i.e. dopa (39), which, curiously, is only used for the elaboration of one of these units (ring A and attached ethanamine residue), being incorporated via dopamine (40). Condensation of dopamine with (38) affords (43), which has been shown to be a benzylisoquinoline precursor followed in sequence by (42). The new results confirm these findings by showing that (42) and (43) are reticuline precursors too. 

C gH 206, Mr 324.29, bronze-colored plates, mp. >300 C. The terphenylquinone A. is found in the brown outer skin of the toadstool Paxillus atrotomen-tosus (Basidiomycetes). In the fruit body of the fungus A. exists in the form of the colorless leucomentin which easily decomposes into A. and the insecticidal osmundalactone. Biosynthetically, A. is formed by condensation of 2 molecules 4-hydroxyphenylpyruvic acid and occurs in the form of esters of various acids in fungi ( aurantiacin, flavomentins, spiromentins). The constitution of A. was elucidated in the 1920 s by F. Kogl. 

In this way, a variety of further amino acids are produced, e.g. alanine from pyruvic acid, serine from hydroxyl pyruvic acid and aspartic acid from oxaloacetic acid, as well as phenylalanine and tyrosine from phenylpyruvic acid and 4-hydroxyphenylpyruvic acid respectively. 

Q 5. With respect to the following biogenetic conversion of chorismic acid (I) to 4-hydroxyphenylpyruvic acid (III), the correct statement is ... 

The effects of this inhibitor on the metabolism of A. fumigatus were very different from those of the other compounds used, since formation of all the characteristic acetate-derived phenols was strongly suppressed (Packter and Collins, 1974). Treatment of cultures gave a completely altered pattern and led unexpectedly to the secretion of atypical shikimic acid-derived phenols, including 2,3-dihydroxybenzoic acid, 4-hydroxyphenylpyruvic acid, and 4-hydroxybenzyl cyanide. In addition, the inhibitor was metabolized directly by transamination to fluorophenylpyruvic acid. 

L-tyrosine is degraded via 4-hydroxyphenylpyruvic acid and homogentisic acid to acetoacetic acid and fumaric acid (Fig. 267). 

Tomoeda K, Awata H, Matsuura T, Matsuda I, Ploechl E, Milovac T, Boneh A, Scott CR, Danks DM, Endo F (2000) Mutations in the 4-Hydroxyphenylpyruvic Acid Dioxygenase Gene Are Responsible for Tyrosinemia Type III and Hawkinsinuria. Mol Genet Metab 71 506-510... 

An example of a transient deficit that is the result of an immature enzyme system is a disorder in which the identification of increased concentrations of tyrosine and 4-hydroxyphenylpyruvic acid (4-HPPA) in urine of a premature newborn would suggest reduced activity of 4-HPPA oxidase. Administration of pharmacological doses of ascorbic acid, the cofactor required for activity of this enzyme, may overcome the temporary oxidase deficit and stimulate catabolism of the accumulating 4-HPPA. Figure 4 is an illustration of this disorder, which is termed transient neonatal tyrosinaemia. 

Figure 4 The urinary organic acids excreted by a premature infant with immature 4-hydroxyphenylpyruvic acid oxidase. This disorder, aiso known as transient neonatai tyrosinaemia, is characterized by excretion of elevated amounts of 4-hydroxyphenylacetic, 4-hydroxyphenyiiactic and 4-hydroxyphenyipyruvic acids. The urine was pretreated with hydroxylamine hydrochloride, which converts the keto acids into the respective oximes.

El Tyrosine transaminase E2 4-Hydroxyphenylpyruvic acid decarboxylase E3 Norcoclaurine syndiase... 

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