Hydroxy phenyl pyruvate

This is a slow process, and the extraction time depends on the type of extractor used. With stirring as described in Note 10, practically quantitative extraction of jb-hydroxy phenyl pyruvic acid can be achieved within 6 hours. Extremely long extraction times may cause decomposition of the product. 

Lindblad, B., G. Lindstedt, and S. Lindstedt. 1970. The mechanism of enzymatic formation of homogentisate from /)-hydroxy phenyl pyruvate. J. Am. Chem. Soc. 92 7446-7449. 

Figure 8. Migration of the side chain during hydroxylation of phenylpyruvates with (hydroxy) phenyl-pyruvic acid oxidase...

Coniferyl alcohol is produced in vivo from glucose (I), via shikimic acid (II), prephenic acid (III), and p-hydroxy phenyl pyruvic acid (IV) ... 

Much of the early understanding of the position of p-hydroxy-phenyl pyruvate oxidation in phenylalanine metabolism arose from the study of metabolic lesions involving tyrosine and phenylalanine (reviewed by Dalgliesh (182)). The period of present interest commences with the demonstration of tyrosine transamination in the presence of ketoglutarate, forming p-hydroxyphenylpyruvate (429, 465), and discovery of soluble enzyme systems which catalyze subsequent oxidation of this substance. 

Subject Phenylacetic Acid Mandelic Acid o-Hydroxy- phenylacetic Acid Phenyllactic Acid Phenyl- pyruvic Acid p-Hydroxy- phenylacetic Acid... 

The approach outlined in Fig. 16.7-6 was used for example to remove traces of d-methionine from 99% pure L-methionine116, 171 or to transform racemic phenylalanine quantitatively into D-phenylalanine and phenyl pyruvic arid1181. Coimmobilization with catalase on a solid matrix (Eupergit ) resulted in largely increased d-AAO stability. In an enzyme-membrane-reactor, space-time-yields as high as 90 g L1 d 1 were reached. In another example, a racemic mixture of D,L-erythro-P-hydroxy-histidine was converted into the ketoacid and L-erythro-P-hydroxyhistidine1191. The... 

Phenol, and ethyl pyruvate were stirred in dichloromethane containing titanium tetrachloride at 0° for 3 h and then at ambient temp, for 5 h to give 1-ethoxycarbonyl, 1-(2-hydroxy-phenyl)ethanol... 

Carboxy-3-chloro-2-hydroxy-3-phenylpropionic acid heated in vacuo (10 mm), whereupon at 180° HCl- and COg-evolution and distillation starts phenyl-pyruvic acid. Y 65%. - This is the last stage of a 4-step synthesis of a-keto-carboxylic acids from alkylidenemalonic esters. F. e. s. B. D. Kulkami and A. S. Rao, Indian J. Chem. 75, 1097 (1975). 

Fig. 16.13 Chromatograms of organic acids extracted using DEAE-Sephadex (upper) and DEAE-Sephadex with solvent re-extraction (lower) from an infant with hereditary tyrosinaemia type I. Separated as their ethoxime and trimethylsilyl derivatives on 10 per cent OV-101 on HP Chromosorb W (80-100 mesh) using temperature programming from 110°C to 285°C at 4°C min with a 5 min initial isothermal delay. Peak identifications are 1, lactate 2, pyruvate 3, sulphate 4, phosphate 5, succinate 6, tetronates 7, aconitate plus homovanillate 8, hippurate 9, citrate plus isocitrate 10, 4-hydroxy-phenyl-lactate 11, 4-hydroxyphenylpyruvate (ethoxime) 12, vanil-lactate 13, 4-hydroxyphenylpyruvate (tri-TMS) 14, urate 15, n-tetracosane (standard) 16, n-hexacosane (standard). (The horizontal axes represent the time elapsed in minutes from sample injection.) The predominance of 4-hydroxyphenyl-lactate and the absence of 4-hydroxyphenylacetate is notable. There is no evidence for the metabolites observed by Lindblad etfl/. (1977) (see Fig. 16.14).

For preparative purposes fermenting baker s yeast (Saccharomyces cerevisiae) is commonly used instead of a purified enzyme preparation. However, isolated pyruvate decarboxylates can also be used30. In this context, the most important substrate is benzaldehyde31 which is converted by n-glucosc fermenting yeast to (7 )-l-hydroxy-l-phenyl-2-propanone. This conversion has gained considerable industrial importance because ( )-l-hydroxy-1-phenyl-2-propanonc is an important precursor for the synthesis of (-)-cphedrin. 

The second example was the pyruvate decarboxylase catalyzed formation of (ll )-l-hydroxy-l-phenyl-2-propanone (PAC) with benzaldehyde as substrate (Fig. 5 a) [64]. This second reaction shows one potential limitation of this method. Some compounds are too volatile for direct measurement by MALDl mass spectrometry or they do not ionize directly due to their nonpolar character. In this case, these compounds have to be derivatized prior to their measurement in order to reduce their volatihty and to introduce ionizable functions. This is, however, often very easy using well estabhshed quantitative reactions, e.g., formation of oximes from aldehydes and sugars (Fig. 5b). 

Fig. 5. a Pyruvate decarboxylase catalyzed formation of (lJl)-l-hydroxy-l-phenyl-2-pro-panone (PAG) using benzaldehyde (BzA) as substrate, b Derivatization of benzaldehyde by formation of an oxime... 

The Schiff bases derived from 5-amino-l,3,6-trimethyluracil with ethyl pyruvate, ethyl phenyl-glyoxalate, or diethyl mesoxalate cyclize in the presence of potassium ethoxide to give the corresponding 6-substituted 7-hydroxy-1.3-dimethylpyrido[3,2-c/]pyrimidine-2,4(l//,3//)-diones 3.439... 

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