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PubMed1993

On the substituent effect of tert-butylaminoxyl group for the acid-dissociation equilibria of alpha-substituted acetic acids.

alpha-Substituted acetic acids with tert-butylaminoxyl groups, t-BuN(O.)-CHX-COOH, were produced as spin adducts in gamma-irradiated aqueous solutions of amino acids and peptides with a spin trap, 2-methyl-2-nitrosopropane. The spin adducts were isolated and characterized by means of high-performance liquid chromatography and EPR spectroscopy. Their EPR spectra in acidic region changed reversibly with pH through the acid-dissociation of the carboxyl groups. The spectra at pH around the pK value were weighted averages of acid forms and conjugate base forms. The pKCOOH values for the dissociation were determined to be 3.0, 3.2, 2.0, 1.8, and 1.6 for t-BuN(O.)-CH2COOH, t-BuN(O.)-CH(CH3)COOH, NH3+CH2CONHCH(COOH)N(O.)-t-Bu, and NH3(+)-*CH(CH3)-CONH-*CH(COOH)N(O.)-t-Bu [a pair of diastereomers], respectively. The electron-withdrawing character of the aminoxyl group is responsible for the observation that the pKCOOH values are lower than those of X-CH2-COOH. The substituent effect of the tert-butylaminoxyl group on the acid-dissociation equilibria of alpha-substituted acetic acids was investigated in relation to the Taft equation. The aliphatic polar substituent constant (sigma*) has been evaluated to be approximately +0.9 for the t-BuN(O.)CH2 group [or the inductive substituent constant sigma 1 approximately +0.4 for the t-BuN(O.) group].

Acetates↗
PubMed1981

Studies on derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid. VI. Syntheses and properties of 2-N-aralkyl-alpha-sulphoderivatives of tert-amides of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

In the course of the studies on compounds with expected antiinflammatory and immunosuppressive activity several new tert-amides derivatives of 2-N-aralkylamino-alpha-sulpho-2-amino-4-p-chlorophenylthiazole-5-acetic acid were synthesized. Some of the previously described Schiff bases reacted with aqueous alcoholic solution of sodium bisulphite and as a result several (III-VIII) alpha-sulphoderivatives were obtained. The course of the reactions was studied and the structure of the new compounds was confirmed.

Amides↗
PubMed1979

Studies on the derivatives of thiazole acetic acid. II. Syntheses and pharmacological analysis of 2-N-aralkylidene and 2-N-aralkyl derivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid.

A number of 2-N-aralkylidene, 2-N-aralkyl and 2-N-aralkyl-alpha-sulphoderivatives of 2-amino-4-p-chlorophenylthiazole-5-acetic acid (I, R = H) and its methyl ester (I, R = CH3) were synthesized. As a result of condensation of methyl ester I with various aromatic aldehydes in boiling benzene solution, the Schiff-bases (anils) II--VIII were obtained. After reduction with NaBH4 compounds II--VIII were transformed into adequate amino esters IX--XV. Esters IX--XV heated with diluted aqueous solution of sodium hydroxide underwent selective hydrolysis giving the respective amino acids XVI--XXII. Some of Schiff bases (II, III, V, VII, VIII) reacted with aqueous alcoholic solution of sodium bisulphite after its several (XXIII--XXVII). alpha-sulphoderivatives had been obtained. Several tests were performed in order to detect the anti-inflammatory and immunosuppressive activity of the compounds. The pharmacological analysis allowed us to draw conclusions concerning the relationship between chemical structure and biological activity in this group of compounds. The most efficacious immunosuppressive and anti-inflammatory activity exhibited 2-aralkyl-alpha-sulphoderivatives.

Adjuvants, Immunologic↗
PubMed2003

Enhancing the efficacy of photodynamic cancer therapy by radicals from plant auxin (indole-3-acetic acid).

Indole-3-acetic acid (plant auxin) has low toxicity but dramatically enhances the killing of mammalian cells on illuminating phenothiazinium dyes with red light. Suitable dyes include toluidine blue, used in cancer diagnosis because of localization in tumors, and methylene blue, used in experimental photodynamic therapy of cancer. The photosensitized oxidation of indole acetic acid forms a free radical that fragments in microseconds, forming reactive cytotoxins. Unlike conventional photodynamic therapy, requiring excitation of oxygen to the reactive singlet state, the treatment is effective even at the low oxygen levels common in tumors and with much lower light doses than normally used.

Animals↗
PubMed1989

Effects of ascorbic acid in alkaptonuria: alterations in benzoquinone acetic acid and an ontogenic effect in infancy.

The effects of ascorbic acid on the excretion of homogentisic acid and its derivative benzoquinone acetic acid were studied in two adults and three infants. The administration of relatively large amounts of ascorbic acid to the adults was followed by a disappearance of benzoquinone acetic acid from the urine, whereas the level of excretion of homogentisic acid did not change. This could have relevance to the pathogenesis of ochronotic arthritis. In the 4-mo-old infant and the 5-mo-old infant ascorbic acid in the urine may have doubled the amount of homogentisic acid, presumably through an effect on the immature p-hydroxyphenylpyruvic acid oxidase. Dietary reduction of the intake of tyrosine and phenylalanine substantially reduced the excretion of homogentisic acid.

Aged↗
PubMed2002

Apparent antifungal activity of several lactic acid bacteria against Penicillium discolor is due to acetic acid in the medium.

Fifty-six dairy bacteria belonging to the genera Lactococcus, Lactobacillus, Pediococcus, Propionibacterium, Streptococcus, Enterococcus, Leuconostoc, and Brevibacterium were screened for antifungal activity against four species of fungi relevant to the cheese industry (Penicillium discolor, Penicillium commune, Penicillium roqueforti, and Aspergillus vesicolor). Most of the active strains belonged to the genus Lactobacillus, whereas Penicillium discolor was found to be the most sensitive of the four fungi investigated. Further studies on P. discolor showed antifungal activity only below pH 5. This effect of pH suggests that organic acids present in the culture could be involved in the detected activity. Determination of acid composition revealed lactic acid production for active dairy strains and the presence of acetic acid in active as well as inactive strains. It was demonstrated that the undissociated acetic acid originates from the bacterial growth medium. The synergistic effect of the acetic acid present and the lactic acid produced was likely the main factor responsible for the antifungal properties of the selected bacteria. These results could explain some discrepancies in reports of the antifungal properties of lactic acid bacteria, since the role of acetic acid has not been considered in previous studies.

Acetic Acid↗
PubMed1972

Acetic acid.

Explore the source record for details and available documents.

Acetates↗
PubMed1999

Role of hydrogen migration in the mechanism of acetic acid elimination from MH(+) ions of acetates on chemical ionization and collision-induced dissociation

The elimination of acetic acid from the MH(+) ions of acetates of stereoisomeric 2-methyl-1-cyclohexanols and 1-hydroxy-trans-decalins exhibits a significant degree of stereospecificity under isobutane chemical ionization and collision-induced dissociation (CID) conditions, resulting in more abundant [MH - AcOH](+) ions in the cis-isomers 4c and 5tc than in their trans-counterparts 4t and 5tt. These findings suggest the involvement of a 1,2-hydride shift from the beta- to the alpha-position in the course of the acetic acid elimination from the MH(+) ions of the above cis-acetates, resulting in tertiary carbocation structures. The proposed mechanism of the elimination is supported by a considerable deuterium isotope effect detected in beta-deuterium-labeled cis-2-methyl-1-acetoxycyclohexane and by a CID study of the structures of the [MH - AcOH](+) ions obtained from cis- and trans-1,2-diacetoxycyclohexanes. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed2003

Oxidative reaction of oxindole-3-acetic acids.

The oxindole-3-acetic acids, oxidative metabolites of indole-3-acetic acid, were isolated from a byproduct of a corn starch manufacturing plant, and were further converted to the 3-hydroxyl derivatives in the presence of metal ion. The mechanical study was followed by a chemical analysis including other byproducts, and suggested the presence of an intermediate that had a radical at the C-3 position of oxindole-3-acetic acids.

Chromatography, High Pressure Liquid↗
PubMed2000

Effects of acid adaptation of Escherichia coli O157:H7 on efficacy of acetic acid spray washes to decontaminate beef carcass tissue.

Exposure to low pH and organic acids in the bovine gastrointestinal tract may result in the induced acid resistance of Escherichia coli O157:H7 and other pathogens that may subsequently contaminate beef carcasses. The effect of acid adaptation of E. coli O157:H7 on the ability of acetic acid spray washing to reduce populations of this organism on beef carcass tissue was examined. Stationary-phase acid resistance and the ability to induce acid tolerance were determined for a collection of E. coli O157:H7 strains by testing the survival of acid-adapted and unadapted cells in HCl-acidified tryptic soy broth (pH 2.5). Three E. coli O157:H7 strains that were categorized as acid resistant (ATCC 43895) or acid sensitive (ATCC 43890) or that demonstrated inducible acid tolerance (ATCC 43889) were used in spray wash studies. Prerigor beef carcass surface tissue was inoculated with bovine feces containing either acid-adapted or unadapted E. coli O157:H7. The beef tissue was subjected to spray washing treatments with water or 2% acetic acid or left untreated. For strains ATCC 43895 and 43889, larger populations of acid-adapted cells than of unadapted cells remained on beef tissue following 2% acetic acid treatments and these differences remained throughout 14 days of 4 degrees C storage. For both strains, numbers of acid-adapted cells remaining on tissue following 2% acetic acid treatments were similar to numbers of both acid-adapted and unadapted cells remaining on tissue following water treatments. For strain ATCC 43890, there was no difference between populations of acid-adapted and unadapted cells remaining on beef tissue immediately following 2% acetic acid treatments. These data indicate that adaptation to acidic conditions by E. coli O157:H7 can negatively influence the effectiveness of 2% acetic acid spray washing in reducing the numbers of this organism on carcasses.

Abattoirs↗
PubMed2002

Induction of endothelial cell apoptosis by the antivascular agent 5,6-Dimethylxanthenone-4-acetic acid.

5,6-Dimethylxanthenone-4-acetic acid, synthesised in this laboratory, reduces tumour blood flow, both in mice and in patients on Phase I trial. We used TUNEL (TdT-mediated dUTP nick end labelling) assays to investigate whether apoptosis induction was involved in its antivascular effect. 5,6-Dimethylxanthenone-4-acetic acid induced dose-dependent apoptosis in vitro in HECPP murine endothelial cells in the absence of up-regulation of mRNA for tumour necrosis factor. Selective apoptosis of endothelial cells was detected in vivo in sections of Colon 38 tumours in mice within 30 min of administration of 5,6-Dimethylxanthenone-4-acetic acid (25 mg x kg(-1)). TUNEL staining intensified with time and after 3 h, necrosis of adjacent tumour tissue was observed. Apoptosis of central vessels in splenic white pulp was also detected in tumour-bearing mice but not in mice without tumours. Apoptosis was not observed in liver tissue. No apoptosis was observed with the inactive analogue 8-methylxanthenone-4-acetic acid. Positive TUNEL staining of tumour vascular endothelium was evident in one patient in a Phase I clinical trial, from a breast tumour biopsy taken 3 and 24 h after infusion of 5,6-Dimethylxanthenone-4-acetic acid (3.1 mg x m(-2)). Tumour necrosis and the production of tumour tumour necrosis factor were not observed. No apoptotic staining was seen in tumour biopsies taken from two other patients (doses of 3.7 and 4.9 mg x m(-2)). We conclude that 5,6-Dimethylxanthenone-4-acetic acid can induce vascular endothelial cell apoptosis in some murine and human tumours. The action is rapid and appears to be independent of tumour necrosis factor induction.

Adenocarcinoma↗