Pyruvic acid, -hydroxyphenyl

Mechanism of reaction. The adduct of malvidin-3-glucoside with pyruvic acid, also known as vitisin A(Fig. 9A.3h), was firstly detected in fortified red wines (Bakker et al. 1997) and in a grape marc (Fulcrand et al. 1998) and further isolated and characterized by NMR (Bakker et al. 1997 Fulcrand et al. 1998). According to Fulcrand et al. (1998), the reaction between pyruvic acid and grape anthocyanins occurs through a series of steps similar to those previously described for the hydroxyphenyl-pyranoanthocyanins (Sect. 9A.2.4.1 Fig. 9A.3f). Later studies performed by NMR (Mateus et al. 2001b) and mass spectrometry (Asenstorfer et al. 2001 Hayasaka and Asenstorfer 2002) have confirmed the structure proposed by Fulcrand et al. (1998). This mechanism is extended to the condensation reaction between anthocyanins and other enolizable precursors found in wine (Benabdeljalil et al. 2000). 

A significant increase in the measured COj concentration was observed after the addition of 10 mmol/1 of a-keto-isovaleric acid (148% increase from baseline), a-keto-isocaproic acid (120%), phenylacetic acid (100%), DL-a-keto-P-methyl-A-valeric acid (100%), homogentisinic acid (50%), P-phenylpyruvic acid (45%), hydroxyphenyl acetic acid (32%), propionic acid (25%), ace-toacetic acid (25%), hydroxyphenyl pyruvate acid (23%), and 20 mmol/1 of hydroxyphenyl lactid acid (65%) or salicylic acid (76%). A significant decrease was observed after the addition of 20 mmol/1 of ascorbic acid (33%), DL- -hydroxybutyric acid (25%) or imidazole lactic acid (25%). No effect after the addition of 10 mmol/1 of imidazole-4-acetic acid, methylmalonic acid, 5-hy-droxyindole acetic acid or 20 mmol/1 arginosuccinic acid, Z.-(+)-hydroxybu-tyric acid (E525). 

It is fortunate that Medes was available to make such a complete and able investigation, as no further eases of tyrosinosis have been reported and the metabolic defect must therefore be exceedingly rare. (There having been only one case recorded nothing is, of course, known of the genetics of its inheritance). Recently, however, other cases of p-hydroxyphenyl-pyruvic acid excretion have been observed, and though these are probably of a different type it is convenient to consider them here. 

The existence of a multiple specific enzymatic deficiency during phenylketonuria has been suggested by Boscott and Bickel (B26) to explain the abnormal excretion of aromatic acids other than phenyl-pyruvic acid, phenyllactic acid, and phenylacetylglutamine, as well as that of indolic acids. Jervis (J3) has, however, stated very recently that it is not necessary to postulate such a multiple enzymatic deficiency, since the complete biochemical urinary picture of phenylketonuria (including the presence of phenyl, hydroxyphenyl, and indolyl compounds) can be obtained temporarily in normal individuals following ingestion of large amounts of phenylalanine. 

Figure 1.16 C-methylation via DMAPP. (a) Hydroxyphenyl pyruvic acid, (b) indole intermediate leading to lysergic acid, and (c) indole intermediate leading to roquefortine.

Alkaloids possessing the 1-benzylisoquinoline skeleton are biosynthesized from two molecules of tyrosine, which are differentiated at the beginning of the biosynthetic pathway. Namely, the isoquinoline moiety, except for one carbon, originates from 3, 4 -dihydroxyphenylethylamine (dopamine), which is formed from tyramine following the decarboxylation of tyrosine. The other part of the alkaloid is derived from 4 -hydroxyphenylac-etaldehyde, which is formed from tyrosine via 4 -hydroxyphenyl pyruvic acid. These two compounds are coupled stereoselectively to give (S)-norcoclaurine. (S)-Norcoclaurine is transformed into (S)-coclaurine by 6-O-methylation, and further N-methylation, hydroxylation at the... 

Dibromo-4-hydroxy-(X-oxobenzenepropanoic acid. 3- 3,5-Dibromo-4-hydroxyphenyl)-2-hydroxy-2-propenoic acid. 3,5-Dibromo-4-hydroxyphenyI)pyruvic acid [13990-07-3]... 

Among indigenous compounds of the body, for which an inhibitory effect on the decarboxylation of OL-amino-acids has been established, phenylpyruvic acid, ° phenyl acetic acid, " V-hydroxyphenyl pyruvic acid, ... 

Recently extracts of acetone powder and homogenates of liver have been obtained which specifically oxidize tyrosine, p-hydroxyphenyl-pyruvic acid, and homogentisic acid to acetoacetic acid. The reaction is aerobic and requires the uptake of 4 atoms of oxygen per molecule for the oxidation of either L-tyrosine or p-hydroxyphenylpyruvic acid to yield 1 molecule of CO2 and 1 of acetoacetic acid oxidation of homogentisic acid to acetoacetate requires the uptake of 2 atoms of oxygen. 

Prephenic acid (86) is readily transformed with acid to give phenyl pyruvic acid (89) but is somewhat more stable towards alkali. However, on heating or prolonged standing in dilute alkaline solution it is converted to p-hydroxyphenyl lactic acid (87). Several proposals have been put forward to account for the formation of this product under these conditions and one of these is shown in Figure 2.13. 

Phenolphthalein, 32 Phenothiazine, 67 Phenylacetic acid, 49, 51, 53 Phenylbutyl methyl ketone, 53 Phenylethyl alcohol, 51 Phenylethyl methyl ketone, 53 Phloretin, 43 Phloridzin, 27, 30, 43 Phloroglucinol, 42 Phosphoglycerate, 31 Physical constants, 6 Pinacol, 38 Pinene, 75 Piperonal, 53 Piperonylic acid, 51 Porphyrin, 63 Pregnanediol, 83, 84 Progesterone, 84 Propiophenone, 54 p-hydroxy-, 55 n-Propyl alcohol, 37 Propylene glycol, 38 Protocatechuic acid, 50 Protocatechuic aldehyde, 52 Z-Pulegol, 72 d-Pulegone, 72 Pyramidone, 63, 67 Pyridine, 63 Pyruvic acid, 11, 31 o-hydroxyphenyl-, 66... 

Tyrosinosis.—An inability to metabolise all the phenylalanine and tyrosine of the diet, the surplus being excreted as tyrosine or its deamination product, hydroxyphenyl pyruvic acid. 

Knox (483) has purified 100-fold an enzyme converting p-hydroxyphenyl-pyruvate to homogentisate. The system requires either ascorbic acid or dichlorophenolindophenol, and appears to be much more active than systems previously reported. The conversion occurs in one step. Details of the reaction are awaited with interest especially as 2,5-dihydroxyphenyl-pyruvate appears to be neither an intermediate nor an inhibitor (209a). 

Abbreviations used are GSH, glutathione ACTH, adrenocorticotropic hormone DPN and TPN, di- and triphosphopyridine nucleotides pHPP, p-hydroxyphenyl-pyruvate and DHA, dehydroascorhic acid. 

The oxidative decarboxylation of prephenic acid to form p-hydroxyphenyl pyruvate is similar, in that it is coupled to an NAD+-linked oxidation (Scheme V). However, there are several important differences. In the first place, this enzyme... 

Tyrosine can arise from two major sourcesone is dietary tyrosine and the other is from phenylalanine that is converted to tyrosine. Tyrosine is further metabolized via a number of different pathways the major quantitative pathway of metabolism occurs in the liver. Almost all essential amino-acid metabolism, with the exception of the branched-chain amino acids, occurs primarily in the liver. Tyrosine is transaminated, with a-ketoglutarate being the acceptor, to form / -hydroxyphenyl pyruvate and glutamate (Fig. 19.2). This reaction is freely reversible. 

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