4 -Hydroxyphenylacetic acid and

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

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... 

Disposition in the Body. Variably absorbed after oral or rectal administration and distributed into the synovial fluid. Metabolised by glucuronic acid conjugation, some conjugation with glycine, deallylation to form 3-chloro-4-hydroxyphenylacetic acid, and hydroxylation to form 3-chloro-4-(2,3-dihydroxypro-pyloxy)phenylacetic acid, which may be methylated an epoxide... 

ND= not determined 4-HPA is 4-hydroxyphenylacetic acid and the complete reaction mix for MnP contained enzyme, buffer, H2O2, and Mn. 

Correlations Between a Fluorimetric and Mass Fragmentographic Method for the Determination of 3-Methoxy-4-hydroxyphenylacetic Acid and Two Mass Fragmentographic Methods for the Determination of 3-Methoxy-4-hydroxyphenylethylene Glycol in Cerebrospinal Fluid J. Neurochem. 32(1) 191-194 (1979) ... 

The early studies of phenohc compounds have been carried out in 1965 [41] and in 1978 [42]. They reported on phloroglucin, protocatechuic acid, 4-hydroxybenzoic acid, syringic acid, vanillic acid, phenylacetic acid, 4-hydroxyphenylacetic acid, and 2-hydroxyphenylacetic acid. 

In recent years, boric acid has been used in direct amidation from laboratory scale to the industrial proportion. Thus, the syntheses of some important drugs have been explored by a number of pharmaceutical laboratories recently. From 2006, GSK synthesized efaproxiral (23) using 7.7 mol% of boric acid loading in the direct amidation of 4-hydroxyphenylacetic acid and 3,5-dimethylaniline in toluene using Dean-Stark water removal for 18 hours (86-95% yield), as shown in Scheme 13.2. ... 

In addition to this major advantage of comprehensive data collection, repetitive scanning techniques form the basis of other approaches to the analysis of multicomponent mixtures. Most common of these is the selected ion plot in which the block of mass spectral data from a repetitive scan run is inspected for particular ions. These are then represented as a plot of ion intensity versus scan number (see Figs. 5.8 and 5.9). In these figures, ions characteristic of spectra of 4-hydroxyphenylacetic acid and pentonic acids are plotted, and their positions in the chromatogram can be clearly seen. As the pentonic acid isomers are eluted under the peaks of hippuric and citric acids, their detection in composite spectra is not always definitive. 

Fig. 5.14 Mass spectra of the methyl esters of (a) benzoic acid, (b) 4-hydroxyphenylacetic acid and (c) mandelic acid and (d) of the methyl ester-trimethylsilyl ether of 3-hydroxybutyric acid.

Aromatic acids other than hippuric and 4-hydroxyphenylacetic acid and a few of exogenous (dietary) origin are generally observed in urine from normal subjects at very low levels, if at all, since those acids that occur in normal... 

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... 

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... 

Fio. 36. Vloi t Hoff plou of the retention bctors of aromatic acids in reversed-phase chromatography using octadecyl silica as the stationaiy phase and neat aqueous 30 taM NaHiPO buffer (pH 2.0) (open symbols), or the same buffer containing 696 (v/v) of aceloni ti (closed symbols) as the eluent. Column S imSpherisorbODS, 230 x 4.6 mm. Eluites 3.4xlihydroxymandelic acid (O. ) 4 hydroxymandelic acid ( , ) 4-hydroxyphenylacetic acid (7. ) 3,4-dihydroxyphenylacetic acid (A, A). Reprinted with permission from Me-lander tt at. U77). 

Other phenolic acids and derivatives 4- (Acetoxythyl) -1,2 -dihydroxybenzene Dopac (3,4-dihydroxyphenylacetic acid) 4-hydroxyphenylacetic acid COOH HO- HO Lignans (+)-l-Acetoxypino resinol (+)-Pinoresinol, / (+)-Hydroxypinoresinol "7 WR OCH3 HO OCH3... 

The test sample to use in qualification should be a small molecule that is soluble in water, has a strong UV chromophore, and possesses a charge at the intended separation pH value. A nonvolatile compound is also desirable, especially when used for assessing peak area reproducibility during the detector linearity test. Some examples of test samples that can be used are benzoic acid, 4-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, and 4-hydroxyacetophenone. 

Fig. 3.1.7 Detection of HG by the GC-MS TIC method in the urine of patients with MCAD deficiency collected at different clinical statuses. A, left panel Organic acid profile of an acutely ill patient. The arrow indicates the portion of the chromatogram shown in the middle panel. Peak labeling 1 HG, 2 4-hydroxyphenylacetic acid. Right panel extracted ion chromatograms of the [M-15]+ ion of HG (m/z 230 red) and 4-hydroxyphenylacetic acid (m/z 281). Patient recovering from an acute episode. C Asymptomatic patient. The latter profile represents a situation where there is a high probability that HG may not be detected by a GC-MS TIC method...

Carboxylic acids, acyl chlorides, and sulfonyl chlorides used for deri-vatization of 4-aminophenylalanine and >-4-am i n op h e ny I a I a n i n e are as follows 5-hydantoinacetic acid, / ran, v - 4 - co t i n i n ec a r b o xy I i c acid, isonicotinic acid, 3-pyridinepropionic acid, 4-hydroxyphenylacetic acid, 2-butynoic acid, 2-pyrazinecarboxylic acid, cyclopropanecarboxylic acid, 3-hydroxy-2-qui-noxaline carboxylic acid, 5-bromovaleric acid, propargyl chloroformate, 3,4-dimethoxybenzoyl chloride, 2-thiophenesulfonyl chloride, 3-thiophene-carboxylic acid, 2-thiophenecarboxylic acid, 2-methylbutyric acid, 2-thio-pheneacetyl chloride, benzoic acid, furylacrylic acid, 4-nitrophenyl acetic acid, 2,5-dimethoxyphenylacetic acid, p-toluenesulfonyl chloride, 4-(di-methylamino)phenylacetic acid, 3-indolepropionic acid, phenoxyacetic acid, 3-(dimethylamino)benzoic acid, cyclohexanecarboxylic acid, naphtha-lenesulfonyl chloride, 4-bromophenylacetic acid, 4-bromobenzoic acid, 2-phenoxybutyric acid, 3,4-dichlorophenylacetic acid, (l-naphthoxy)acetic acid. 

Rump [17] has described a cellulose thin layer method for the detection of phenolic acids such as iw-hydroxybenzoic acid, iw-hydroxyphenylacetic acid and m-hydroxyphenylpropionic acid, in water samples suspected to be contaminated with liquid manure. The phenolic acid is extracted with ethyl acetate from a volume of acidified sample equalling lmg of oxygen consumed (measured with potassium permanganate). The ethyl acetate is evaporated and the residue dissolved in ethanol. After spotting of a lpm aliquot on a cellulose plate the chromatogram is developed by capillary ascent with the solvent n-propanol-w-butanol-25% NH3-water (4 4 1 1 by vol). The solvent front is allowed to advance 10cm. The air-dried plate is sprayed with a diazotised p-nitroanilinc reagent to make the phenolic acids visible. 

A fluorimetric assay method for the determination of acetylcholine with picomole sensitivity was reported by MacDonald [44]. The method is based on the hydrolysis of acetylcholine to choline and acetate, catalyzed in the presence of acetylcholineesterase, oxidation of choline to betaine, and H202 in the presence of choline oxidase, and oxidation of 4-hydroxyphenylacetic acid by H202 to a fluorescent product, catalyzed by peroxidase. The interference in the analysis of brain homogenates was discussed. 

C17. Crow, J. P., Measurement and significance of free and protein-bound 3-nitrotyrosine, 3-chlorotyrosine, and free 3-nitro-4-hydroxyphenylacetic acid in biologic samples A high-performance liquid chromatography method using electrochemical detection. Meth. Enzymol. 301, 151-160(1999). 

Aryl esters of 4-hydroxybutyric acid, 5-hydroxyvaleric acid, 2-hydroxyphenylacetic acid, and 3-(2-hydroxyphenyl)propionic acid lactonize with rate constants proportional to iopH picw (Capon et al., 1973). The second-order rate constant at 30° for lactonization of phenyl 4-hydroxybutyrate is ca. 3000 times greater than kOH for hydrolysis of phenyl acetate at 25°. Lactonization of phenyl 4-hydroxybutyrate is catalysed by acetate and phosphate buffers in... 

Monoamine oxidase catalyzes the conversion of dopamine to 3,4-dihydroxy-phenylacetic acid and tyramine to 4-hydroxyphenylacetic acid. Phenol sulfo-... 

Disposition in the Body. Dopamine is a naturally occurring catecholamine and is considered to be the metabolic precursor of noradrenaline. It is inactivated after oral administration. It is excreted mainly as 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid) noradrenaline and 3-methoxytyramine are also metabolites. Dopamine is a metabolite of levodopa. 

Disposition in the Body. Rapidly absorbed from the small bowel after oral administration and widely distributed in the tissues less than 1% of a dose reaches the brain bioavailability about 33%. Extensively metabolised mainly by decarboxylation to dopamine, which is further metabolised, and also by methylation to 3-0-methyldopa which accumulates in the central nervous system most of a dose is decarboxylated by the gastric mucosa before entering the systemic circulation the decarboxylase activity is inhibited by carbidopa and benserazide. Dopamine is further metabolised to noradrenaline, 3-methoxytyramine, and to the two major excretory metabolites, 3,4-dihydroxyphenyl-acetic acid (DOPAC) and 3-methoxy-4-hydroxyphenylacetic acid (homovanillic acid, HVA). During prolonged therapy, the rate of levodopa metabolism appears to increase, possibly due to enzyme induction. About 70 to 80% of a dose is excreted in the urine in 24 hours. Of the material excreted in the urine, about 50% is DOPAC and HVA, 10% is dopamine, up to 30% is... 

Pryor and coworkers have shown that peroxynitrite-mediated nitrosations and nitrations of phenols are modulated by CO2. The reaction was found to be first order with respect to peroxynitrite and zero order with respect to phenol, showing that an activated intermediate of peroxynitrite, perhaps the peroxynitrite anion-C02 adduct (0=N—OO—C02 ), is involved as the intermediate (equation 57) . At pH higher than 8.0, 4-nitrosophenol is the major product, whereas in acidic media significant amounts of the 2- and 4-nitrophenols were formed. Peroxynitrite also induces biological nitration of tyrosine residues of the proteins. The detection of 3-nitrotyrosine is routinely used as an in vivo marker for the production of the cytotoxic species peroxynitrite (ONOO ). It was shown that nitrite anion (N02 ) formed in situ by the reaction of nitric oxide and hypochlorous acid (HOCl) is similarly able to nitrate phenolic substrates such as tyrosine and 4-hydroxyphenylacetic acid . 

A method for the synthesis of cyclic oligoribonucleotides has been described. A TOM-protected RNA phosphoramidite is attached to a CPG linker via 3-chloro-4-hydroxyphenylacetic acid, attached to the phosphoramidite, which is then oxidised to yield the phosphotriester attached to the solid support. RNA synthesis is carried out in the usual manner, and cydisation of the terminal 5 -hydroxyl group to the 3 -phosphodiester occurs using MSNT. A variety of cyclic ODNs were prepared, though cydisation yields were only of the order of 15%. 

The taxonomic application of the ability of enteric organisms to grow with hydroxylated 4-hydroxyphenylacetate (Cooper and Skinner 1980) and of 3-hydroxyphenylpropionic acid (Burlingame and Chapman 1983) has been established, and it has been demonstrated that the enzyme that carries out the hydroxylation has a wide substrate range extending to 4-methylphenol and even to 4-chlorophenol (Prieto et al. 1993). 

Hareland, W.A., R.L. Crawford, P.J. Chapman, and S. Dagley. 1975. Metabolic function and properties of 4-hydroxyphenylacetic acid 1-hydrolase from Pseudomonas acidovorans.. Bacteriol. 121 272-285. 

Figure 11.6.8 Liquid chromatographic separation of tryptophan and tyrosine metabolites using amperometric detection with a glassy carbon working electrode at 0.65 V vs. Ag/AgCl in a thin-layer cell. NE, norepinephrine EPI, epinephrine DOPAC, 3,4-hydroxyphenylacetic acid DA, dopamine 5-HIAA,...

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