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PubMed2002

NADH oxidation by manganese peroxidase with or without alpha-hydroxy acid.

NADH oxidation by manganese peroxidase (MnP) was done in a reaction mixture including either alpha-hydroxy acid or acetate. The oxidation in the former reaction mixture was inhibited by a catalase and was accelerated by exogenous H2O2, while the oxidation in the latter reaction mixture was inhibited by a superoxide dismutase and was not accelerated by the exogenous H2O2. These results indicated that there are significant differences between the two reaction systems, particularly, in the active oxygen species involved in the reactions. Additionally, the experiment of MnP reduction with Mn(II) suggests that MnP has a separate catalytic activity other than an oxidation of Mn(II) to Mn(III) in the reaction mixture including acetate.

Acetates↗
PubMed1993

Molecular and isotopic analyses of the hydroxy acids, dicarboxylic acids, and hydroxicarboxylic acids of the Murchison meteorite.

The hydroxymonocarboxylic acids, dicarboxylic acids, and hydroxydicarboxylic acids of the Murchison meteorite were analyzed as their tert-butyldimethylsilyl derivatives using combined gas chromatography-mass spectrometry. The hydroxydicarboxylic acids have not been found previously in meteorites. Each class of compounds is numerous with carbon chains up to C8 or C9 and many, if not all, chain and substitution position isomers represented at each carbon number. The alpha-hydroxycarboxylic acids and alpha-hydroxydicarboxylic acids correspond structurally to many of the known meteoritic alpha-aminocarboxylic acids and alpha-aminodicarboxylic acids, a fact that supports the proposal that a Strecker synthesis was involved in the formation of both classes of compounds. Isotopic analyses show these acids to be D-rich relative to terrestrial organic compounds as expected; however, the hydroxy acids appear to be isotopically lighter than the amino acids with respect to both carbon and hydrogen. The latter finding would not be expected if both classes of compounds came exclusively from common precursors as would have been the case for a Strecker synthesis.

Carbon Isotopes↗
PubMed2003

Use of short-end injection capillary packed with a glycopeptide antibiotic stationary phase in electrochromatography and capillary liquid chromatography for the enantiomeric separation of hydroxy acids.

A new chiral stationary phase (CSP) was prepared by reacting MDL 63,246 (Hepta-Tyr), a glycopeptide antibiotic belonging to the teicoplanin family, with 5-microm diol-silica particles. The CSP mixed with 5-microm amino silica particles (3:1) was packed into 75-microm fused-silica capillaries for only 6.6 cm and used for electrochromatographic experiments analyzing several hydroxy acid enantiomers. A reversed electroosmotic flow carried both analytes and mobile phase towards the anode in a short time (1-3 min), being baseline resolved all the studied analytes. In order to achieve the fastest enantiomeric resolution of the studied hydroxy acids, the effect of several experimental parameters such as mobile phase composition (organic modifier type and concentration, pH of the buffer and ionic strength), capillary temperature and applied voltage on enantioresolution factor, retention time, enantioselectivity were evaluated. The packed capillary column allowed the separation of mandelic acid enantiomers in less than 72 s with resolution factor Rs=2.18 applying a voltage of 30 kV and eluting with a mobile phase composed by 50 mM ammonium acetate (pH 6)-water-acetonitrile (1:4:5, v/v). The CSP was also tested in the capillary liquid chromatography mode resolving all the studied enantiomers applying 12 bar pressure to the mobile phase [50 mM ammonium acetate (pH 6)-water-methanol-acetonitrile, 1:4:2:3, v/v)], however, relatively long analysis times were observed (12-20 min).

Acids↗
PubMed1975

Rat kidney L-alpha-hydroxy acid oxidase: isolation of enzyme with one flavine coenzyme per two subunits.

L-alpha-Hydroxy acid oxidase (listed as EC 1.4.3.2, L-amino acid: O2 oxidoreductase) has been purified 100-fold from rat kidney to apparent homogeneity by gel electrophoresis. A subunit molecular weight of 47,500 was found by sodium dodecyl sulfate gel electrophoresis, but in contrast to previous reports, the enzyme has been found to have a molecular weight of ca. 200,000 by Sephadex gel filtration and by dodecyl sulfate gel electrophoresis of the enzyme cross-linked with dimethyl suberimidate. A somewhat higher value was found by sedimentation equilibrium, but a tetrameric structure for the active enzyme is definitely established. The enzyme was found to contain the FMN coenzyme at a concentration of one FMN/102,000 daltons or one flavine/two subunits, a highly unusual finding. This ratio was determined from spectroscopic analysis of the FMN in lyophilized samples of the enzyme and by titration of the coenzyme with the flavine specific enzyme inactivator 2-hydroxy-3-butynoate. The enzyme has the same specific activity as a crystalline sample of the enzyme reported to have twice as much flavine/milligram.

Amino Acid Oxidoreductases↗
PubMed1998

Understanding alpha-hydroxy acids.

This self-study activity has been developed for nurses, estheticians, and other health care professionals whose patients use alpha-hydroxy acid (AHA) products. Skin anatomy and physiology are reviewed and information is presented on the mechanisms of action of AHAs. Cosmetic and therapeutic benefits of AHA-containing products are detailed. Factors that influence the safety and effectiveness of AHA products are explored, including concentration, pH, and the amount of free acid present. A method is detailed for applying AHA-containing chemexfoliating agents, and guidelines are offered for taking a patient history, post-procedure skin care, and applying subsequent peels.

Chemexfoliation↗
PubMed2005

Determination of alpha-hydroxy acids in cosmetic products by capillary electrophoresis.

In this work, a simple and reliable method for the simultaneous analysis of alpha-hydroxy acids such as tartaric, glycolic and lactic acids in cosmetic products was developed using capillary electrophoresis with indirect UV detection at 254 nm. A buffer solution containing 10 mmoll(-1) potassium phthalate (pH 4.1) and 0.5 mmoll(-1) cetyltrimethylammonium bromide as electroosmotic flow modifier allowed baseline resolution of the analytes in approximately 3 min. A few validation parameters of the proposed method include: good linearity for all compounds in the range from 10 to 100 mgl(-1) with coefficients of correlation larger than 0.9999. The average recoveries of tartaric, glycolic and lactic acids in commercial samples were 99.12, 99.41 and 99.43%, respectively. The method presented acceptable precision with average relative standard deviation of 0.54% (assay of commercial samples), 0.44% (peak area) and 0.16% (migration time).

Cosmetics↗
PubMed1975

Ultrastructural localization of L-alpha-hydroxy acid oxidase in rat liver perioxisomes.

The localization of L-alpha-hydroxy acid oxidase in rat liver peroxisomes was studied using slight modifications of the Shnitka and Talibi (1971) method. Best results were obtained with formaldehyde fixation and incubation with glycolate as substrate. Following incubation the copper ferrocyanide reaction product was amplified with 3,3'-diamino-benzidine according to Hanker et al. (1972a,b). Dense reaction product was visible in hepatocyte peroxisomes by light and electron microscopy. Some diffusion of enzyme and/or reaction product into the adjacent cytoplasm occurred around the peroxisomes. Apparent non-specific deposits occurred on the plasmalemma, in the nucleus, and occasionally over mitochondria. Glutaraldehyde fixation severely inhibited enzymatic activity, and the enzyme showed less activity toward L-lactate and DL-alpha-hydroxybutyrate.

Alcohol Oxidoreductases↗
PubMed2002

Probing the specificity of a trypanosomal aromatic alpha-hydroxy acid dehydrogenase by site-directed mutagenesis.

The aromatic l-alpha-hydroxy acid dehydrogenase (AHDAH) from Trypanosoma cruzi has over 50% sequence identity with cytosolic malate dehydrogenases (cMDHs), yet it is unable to reduce oxaloacetate. Molecular modeling of the three-dimensional structure of AHADH using the pig cMDH as template directed the construction of several mutants. AHADH shares with MDHs the essential catalytic residues H195 and R171 (using Eventoff's numbering). The AHADH A102R mutant became able to reduce oxaloacetate, while remaining fully active towards aromatic alpha-oxoacids. The Y237G mutant diminished its affinity for all of the natural substrates, whereas the double mutant A102R/Y237G was more active than Y237G and had similar activity with oxaloacetate and with aromatic substrates. The present results reinforce our proposal that AHADH arose by a moderate number of point mutations from a cMDH no longer present in the parasite.

Alcohol Oxidoreductases↗
PubMed1970

Gas--liquid chromatography--mass spectrometry of synthetic ceramides containing 2-hydroxy acids.

Ceramides containing either sphingosine or sphinganine and one of the 2-hydroxy acids, 14h:0, 16h:0, 18h:0, 20h:0, 22h:0, 24h:0, and 26h:0 were prepared and separated by gas chromatography as the 1,3,2'-tri-O-tri-methylsilyl derivatives. Mass spectrometric analyses of these derivatives showed that the ions formed on electron impact can be used to determine unequivocally the structures of the long-chain base and the fatty acid residue in the ceramide. Proposed structures of ions and the mechanisms of reaction of their formation are supported by mass spectra of homologous derivatives, by deuterium labeling experiments, and by high-resolution on mass spectrometry.

Amino Alcohols↗
PubMed1982

1-N-acylation of gentamicin C1a by a cyclic, chiral gamma-amino-alpha-hydroxy acid related to the (S)-4-amino-2-hydroxybutyric acid.

A semisynthetic aminoglycoside antibiotic 15, containing a cyclic gamma-amino-alpha-hydroxy acid, related to the 1-N-4-amino-2-hydroxybutyric acid (AHBA) side chain of butirosins and amikacin, has been prepared. Conveniently protected 3,2',6'-tris-N-tert-butoxycarbonylgentamicin C1a (12) was condensed with the phtalimido active ester 10 to give after catalytic reduction and deprotection, the hitherto unknown 1-N-substituted gentamicin C1a 15. The requisite side chain was synthesized from the readily available D-(-)-quinic acid. The antibacterial properties of 15 are given.

Acylation↗
PubMed1984

Calcium ionophore activity of intestinal secretory compounds. An in vitro porcine model for the effects of bile acids, hydroxy-fatty acids and dioctyl sulfosuccinate.

The association between reported intestinal fluid secretory activity of bile acids and Ca2+ ionophore properties was investigated in a pig jejunal brush border vesicle system. Secretory and nonsecretory bile acids and hydroxy-fatty acids were tested to see if Ca2+ ionophore activity is a general property of all bile acids and hydroxy-fatty acids, or if it is confined to compounds with recognized fluid secretory activity. Ionophore activity was attributed to compounds which could increase rates of Ca2+ influx and efflux from brush border vesicles under conditions where nonspecific permeability to sorbitol was not affected. The recognized secretory agents chenodeoxycholate and dioctyl sulfosuccinate had Ca2+ ionophore activity in the test system. The nonsecretory agents cholate, hyodeoxycholate and 4-hydroxybutyrate had no detectable activity, while ursodeoxycholate showed minor ionophore activity. Due to complications resulting from Ca2+ sequestration it was impossible to determine the Ca2+ ionophore activity of 12-hydroxystearate in this system. The detergent properties of all these agents are known to increase intestinal permeability, but detergent strength, as measured by concentration required to increase mannitol exchange across vesicle membranes, did not correlate well with secretory activity. We conclude that intestinal fluid secretion caused by bile acids and hydroxy-fatty acids could be controlled partially by Ca2+ ion interactions which could include intracellular signal effects of Ca2+ on anion permeability of the brush border membrane as well as possible increases in permeability of the tight junctions, and local hypertensive effects.

Animals↗
PubMed2006

Towards developing surface eroding poly(alpha-hydroxy acids).

We have prepared a library of biodegradable polyesters derived from poly(alpha-hydroxy acids) (PHAs) that appear to primarily exhibit surface erosion behavior. This was achieved by increasing the hydrophobicity of the polymers in two distinct steps, namely: macromer formation and a coupling step. In the first step, macromerdiols (MDs) with varying lipophilicities were prepared by polymerization of L-lactide or mixture of L-lactide and glycolide (3/1 by mole) to various lengths (n = 10, 20, 30, and 40) using alkanediols of increasing C-chain length (C6, C8, and C12) as initiators in the presence of Tin(II) catalyst. In the second step, the macromer diols were linked together with diacid dichlorides of varying C-chain lengths (C6, C8, C10, and C12) to yield polyesters ranging in molecular weight (Mw) from 20 to 130 KDa and polydispersity of 1.5-6. These polyesters exhibited different thermal behavior from pure PHAs that can be tuned by changing the initiator core, the lactide/glycolide chain length, and diacid dichloride type. In addition, all these polymers showed solubility in tetrahydrofuran unlike poly(L-lactic acid) (PLLA) and poly(lactide-co-glycolide) (PLGA). In contrast to PLLA and PLGA, the degradation behavior of these novel polyesters exhibited linear profiles consistent with a surface erosion behavior. Release studies using Congo red as a model drug from microspheres prepared from these polyesters showed linear release profiles with correlation constants of least-square fits approaching a value of unity. Degradable polyesters with tunable thermal and degradation behavior may find applications in drug delivery and tissue engineering, where control over these parameters is critical to ensure predictable outcomes.

Absorbable Implants↗
PubMed1970

Mammalian D-2-hydroxy acid dehydrogenase. Effect of inhibitors and reaction sequence.

1. The reaction of d-2-hydroxy acid dehydrogenase with d-lactate and 2,6-dichlorophenol-indophenol (DCIP) at pH8.6 yields reciprocal plots of 1/rate versus 1/[d-lactate], at different DCIP concentrations, which appear to be parallel. However, at pH7.55, or in the presence of the competitive inhibitor oxalate at pH8.6, the plots are convergent. This is inconsistent with the mechanism previously proposed for this enzyme. 2. The pattern of inhibition by the product, pyruvate, is consistent with either an Ordered mechanism or an Iso Theorell-Chance mechanism. 3. The observation that the enzyme forms a complex with d-lactate favours the Ordered reaction. In this, first d-lactate and then DCIP bind to the enzyme to form a ternary complex, from which pyruvate and reduced DCIP dissociate in that order.

Alcohol Oxidoreductases↗