4- Hydroxyphenylacetic acid/4-Hydroxyphenylacetate

Hydroxyphenylacetic acid [614-75-5] M 152.2, m 148-149", b 240-243"/760mm, pKEst(i)-4.3, pKEst(2)-10.1. Crystd from ether or chloroform (m from latter is always lower). 

The synthesis and metabolism of trace amines and monoamine neurotransmitters largely overlap [1]. The trace amines PEA, TYR and TRP are synthesized in neurons by decarboxylation of precursor amino acids through the enzyme aromatic amino acid decarboxylase (AADC). OCT is derived from TYR. by involvement of the enzyme dopamine (3-hydroxylase (Fig. 1 DBH). The catabolism of trace amines occurs in both glia and neurons and is predominantly mediated by monoamine oxidases (MAO-A and -B). While TYR., TRP and OCT show approximately equal affinities toward MAO-A and MAO-B, PEA serves as preferred substrate for MAO-B. The metabolites phenylacetic acid (PEA), hydroxyphenylacetic acid (TYR.), hydroxymandelic acid (OCT), and indole-3-acetic (TRP) are believed to be pharmacologically inactive. 

CiiHiyN O 76610-81-6) see Cetbuperazone 0( -)< a>(2t3 dioxo-4 ethyl l>piperazmocarbonylamino) 4-hydroxyphenylacetic acid... 

Oxidant production is measured with the fluorogenic substrate para-hydroxyphenylacetic acid (PHPA) in the presence of superoxide dismutase and peroxidase (9). Under these conditions, superoxide is converted to H2O2 by the superoxide dismutase, and two molecules of PHPA are converted to a fluorescent diadduct by H2O2 and peroxidase. Similar assays have been devised using homovanillic acid (16) or scopoletin (17) instead of PHPA. 

A polynucleoside with an unnatural polymeric backbone was synthesized by SBP-catalyzed oxidative polymerization of thymidine 5 -p-hydroxyphenylacetate. Chemoenzymafic synthesis of a new class of poly(amino acid), poly(tyrosine) containing no peptide bonds, was achieved by the peroxidase-catalyzed oxidative polymerization of tyrosine ethyl esters, followed by alkaline hydrolysis. Amphiphile higher alkyl ester derivatives were also polymerized in... 

Sparnins VL, PJ Chapman, S Dagley (1974) Bacterial degradation of 4-hydroxyphenylacetic acid and... 

Brachiaria mutica, dried leaves Vanillic, p-hydroxybenzoic, o-hydroxyphenylacetic acids 74... 

Panicum maximum, dried leaves p-Hydroxyphenylacetic acid 74... 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

Creosol (also called 2-methoxy-jb-cresol, 4-methylguaiacol, and 3-methoxy-4-hydroxytoluene) has been obtained by the fractionation of beach creosote tar,4 by the reduction of vanillin by electrolytic methods,6 6 by hydrogen and palladium on charcoal or barium sulfate,7 8 with hydrazine,9 and by amalgamated zinc and hydrochloric acid.3 10 11 It has also been prepared by methyl-ation of 4-methylcatechol with methyl iodide 12 13 or with methyl sulfate 14 and is reported to be formed by the distillation of the calcium salt of 3-methoxy-4-hydroxyphenylacetic acid.16... 

Metabolites of biogeiuc amines have also been analyzed by GC-ECD. For the simultaneous analysis of 5-hydroxyindole-3-acetic acid (5-HIAA), homovanillic acid (HVA) and m- and p-hydroxyphenylacetic acid (m-, p-HPAA), (metabolites of 5-HT, DA, and m- and p-tyramine acid respectively) in urine, a simple acidic extraction followed by derivatization with PFPA (derivatizes phenols) and hexafluoroisopropanol (deriva-tizes carboxylic acid groups) has been used (Davis et al., 1982 Baker et al., 1987). 

Baker GB, Yeragani VK, Dewhurst WG, Coutts RT, Mac Donald RN, et al. 1987. Simultaneous analysis of urinary m- and p-hydroxyphenylacetic add, homovanillic acid and 5-hydroxyindole-3-acetic acid using electron-capture gas chromatography. Biochem Arch 3 257. 

A number of different reaction conditions were investigated for the Mitsunobu reaction and DIAD/PPh3 proved to be the most efficient combination of reagents. The dendronized support was then compared with the conventional TentaCel resin keeping the scaffold on the resin constant (glycine and 4-hydroxyphenylacetic acid) and employing four different alcohols. Much better yields were obtained... 

Gracin, S. and Rasmuson, A.C. Solubility of phenylacetic acid, p-hydroxyphenylacetic acid, p-aminophenylacetic acid, p-hydroxybenzoic acid, and ibuprofen in pure solvents, / Chem. Eng. Data, 47(6) 1379-1383, 2002. 

The authors report detection limits of 8x10 ° mol/dm for TATP and 8 X lO mol/dm for HMTD. When p-hydroxyphenylacetic acid (p-HPAA) (6) was used as the oxidation substrate instead of ABTS, a highly fluorescent dimer (7) was formed. This dimer could be detected spectrophotometricaUy, although the sensitivity dropped (Eq. (12)). Both methods also enabled a semi-quantitative estimation of TATP and HMTD concentrations [86]. Dimerization of p-hydroxyphenylacetic acid (p-HPAA) by hydrogen peroxide in presence of peroxidase [86] is as foUows ... 

Aryl esters of 4-hydroxyhutyric acid, 5-hydroxyvaleric acid, 2-hydroxyphenylacetic acid, and 3-(2-hydroxyphenyl)propionic acid lactonize with rate constants proportional to (Capon et... 

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