Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MALIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1990

Experimental sports drinks with minimal dental erosion effect.

The effects of new experimental sports drinks on dental enamel were studied in vitro using bovine tooth specimens. Profilometric analysis was used to measure the loss of tooth material after immersion of the specimens in the drinks. Thereafter the specimens' surface hardness was measured and scanning electron microphotographs were taken. In addition, 13 commercial sports drinks and experimental drinks containing either citric acid or malic acid were tested for their capacity to dissolve hydroxyapatite in vitro. The erosive effect increased markedly with decreasing pH. The citric acid containing drinks were more erosive than malic acid containing drinks. No erosion was observed with the malic acid containing drink (pH 5.90) but the drink of similar composition containing citric acid caused an erosion 1.3 +/- 1.1 microns deep and a commercial citric acid containing drink caused a lesion 12.3 +/- 4.5 microns deep after 120 min immersion. Softening of enamel was greater in specimens immersed in citric acid than in those immersed in malic acid containing drink. The in vitro hydroxyapatite dissolving effect of the commercial sports drink samples studied (all having a pH under 4.22) was markedly greater (0.48-4.38 mmol/l) than that of the malic acid containing experimental drink (pH 5.50, Ca++ concentration in the supernatant 0.19 mmol/l) and of the similar citric acid containing drink (0.35 mmol/l). The hydroxyapatite dissolving effect of both drinks started to be marked at a pH level of about 5.0 but increased thereafter exponentially with decreasing pH. At pH levels above 4.0 the hydroxyapatite dissolving effect of citric acid containing drinks was greater than that of malic acid containing drinks.

Animals↗
PubMed1998

The effect of glycolic acid on cultured human skin fibroblasts: cell proliferative effect and increased collagen synthesis.

Glycolic acid peeling is known to improve photoaging processes such as wrinkling and roughness, but this effect has not been clearly defined, even though functional activation of fibroblasts has been suggested. The study was aimed to determine the effects of glycolic acid and malic acid (AHA: alpha hydroxy acid) on cultured dermal fibroblasts. Whether it directly increases cell proliferation may be an important factor influencing the production of extracellular matrix such as type I collagen. Cultured human skin fibroblasts were treated for 24 hours with glycolic acid and malic acid at different concentrations (10(-4), 10(-5), 10(-6) M), and cell proliferation was measured by MTT assay. Then quantitative analysis of collagen synthesis was performed by PICP (Procollagen Type I C-peptide) enzyme immunoassay and radioisotope (3H-proline) labelled collagen assay. The results showed increased cell proliferation and collagen production in response to glycolic acid in a dose dependent manner. The range of cell proliferation and collagen production were significantly higher with glycolic acid treatment than with malic acid or control. It was suggested that the favorable effects of glycolic acid treatment on aging skin were mediated by increased cell proliferation in addition to functional activation of fibroblasts.

Cell Division↗
PubMed2001

Chiral separation of amino acid esters by micellar electrokinetic chromatography.

Micellar electrokinetic chromatography (MEKC) was used for the chiral separation of uncharged analytes (C- and N-protected amino acids). Sodium dodecyl sulfate (SDS) was the micelle forming agent, and different cyclodextrin (CD) derivatives were added as chiral selectors. Suitable conditions for the enantioseparation were found by variation of the separation conditions. The influence of addition of organic solvents like acetonitrile or methanol, and other chiral additives (camphor-10-sulfonic acid, malic acid) was examined. The addition of an organic modifier resulted in different effects on micelle formation, and thereby on the separation. The used chiral additives did not improve the selectivity. Furthermore, dependence of the electroosmotic flow (EOF), and the capacity factors on the concentration of CDs was investigated. Increasing the CD concentration, both the EOF to a smaller extent as well as the capacity factors decrease. Nevertheless, the enantioseparation is improved with a CD-concentration up to 30 mM. Higher CD-concentrations reduce the separation of the analytes.

Acetonitriles↗
PubMed1999

Effects of Carboxylic Acids on Calcite Formation in the Presence of Mg2+ Ions.

The effects of seven carboxylic acids on calcite formation in the presence of Mg2+ ions, whose molar concentration ratio Mg2+/Ca2+ = 0.5 exclusively induced aragonite precipitation in the absence of carboxylic acids, were studied using a double diffusion technique. The presence of carboxylic acids, acrylic acid, maleic acid, tartaric acid, malonic acid, malic acid, succinic acid, and citric acid in the gel medium favored the formation of magnesian calcite relative to the amount of the additives. Induction time and the positions of the first precipitation were measured to analyze the behavior of crystallization based on the equivalency rule. The formation of magnesian calcite was also studied with the help of Avrami's equation (solid-state model for transformation). The results of applying this equation suggested that aragonite transformed into calcite through a solid-to-solid process. The formation of magnesian calcite was interpreted as the following process: aragonite nuclei, formed owing to Mg2+ ions at the initial stage of CaCO3 crystallization, transformed into calcite nuclei through a solid-to-solid process while their growth was inhibited by the adsorption of carboxylic acids. The magnesian calcite crystals grew on crystal seeds of calcite formed from aragonite nuclei. Copyright 1999 Academic Press.

Journal Article↗
PubMed2001

Effects of Carboxylic Acids on the Crystallization of Calcium Carbonate.

The effects of seven carboxylic acids, i.e., acrylic acid, maleic acid, tartaric acid, malic acid, succinic acid, and citric acid, on CaCO(3) crystallization were studied using the unseeded pH-drift method along with a light-scattering technique. Experiments were started by mixing solutions of CaCl(2) and NaHCO(3) in the presence or absence of additives. The crystallization was studied by recording the decrease in pH resulting from the reaction Ca(2+)+HCO(3)(-)-->CaCO(3)+H(+). A given amount of carboxylic acid was added to the solution of CaCl(2) or NaHCO(3) before mixing the reactants. The pH profiles obtained in the case of the CaCl(2) solution containing an additive were similar to those for the NaHCO(3) solution containing one, and when an additive was added after the onset of crystallization, the growth of CaCO(3) immediately stopped. The light-scattering observations, in all cases, indicated that CaCO(3) nucleation occurred at 10-20 s after mixing of the reactants. The results indicated that the nucleation of CaCO(3) was not influenced by the presence of carboxylic acids, but CaCO(3) crystal growth was reduced by their adsorption to the surface of the CaCO(3) crystals. These phenomena were explained by assuming a stronger affinity of the carboxylic acids for CaCO(3) particles than for the free Ca(2+) ions in solution. The crystallization of CaCO(3) in the presence of additives was divided into three stages: nucleation, growth incubation, and growth periods. Copyright 2001 Academic Press.

Journal Article↗
PubMedDate not supplied

The removal of strontium from the mouse by chelating agents.

The effects of the chelating agents monosodium glutamate, Tiron, tartaric acid, ascorbic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), 2,3-dimercaptosuccinic acid (DMSA), succinic acid, malic acid, ethylendiaminetetraacetic acid (EDTA), ethylenglycol-bis-(beta-amino-ethylether)-N,N'tetraacetic acid (EGTA), cyclohexane-diaminetetraacetic acid (CDTA) and diethylentria-minepentaacetic acid (DTPA) on the distribution and excretion of intraperitoneally injected strontium were investigated in male Swiss mice. Strontium nitrate was given at a dose equal to 3.78 mmol/kg and ten minutes after, chelators were administered intraperitoneally at doses approximately equal to one-fourth of their respective LD50 values. DTPA, followed by CDTA, EDTA and tartaric acid, was consistently the most effective in increasing the urinary excretion of strontium. Only ascorbic acid increased significantly the fecal excretion of strontium. CDTA, DTPA and ascorbic acid were also the most effective chelators in reducing the concentration of strontium found in various tissues. CDTA, DTPA and tartaric acid are the most effective agents of those tested in the removal of strontium after a single administration.

Animals↗
PubMed2006

Immobilized cell reactors in mineralization of dicarboxylic acid solid waste.

Dicarboxylic acid solid waste containing phthalic acid, malic acid, quinone, saturated and unsaturated dicarboxylic esters etc., are discharged in huge quantities during the crackdown of benzene over the catalyst vanadium at temperatures greater than 500 degrees C in a dicarboxylic acid manufacturing industry. Concern over the biological effects of these compounds underlines the necessity to treat this solid waste. The role of yeast Saccharomyces cerevisiae and anaerobic mixed bacterial cultures immobilized in activated carbon, in sequential two stage anoxic reactors, were investigated for the degradation of dicarboxylic acid solid waste (DASW). In the first stage, DASW was dissolved in water to yield a concentration of 0.5% w/v and was treated in yeast Saccharomyces cerevisiae immobilized reactor at an optimum residence time of 24 h. The yeast fermented samples were further treated in an upflow anaerobic reactor containing mixed culture immobilized in activated carbon at an Hydraulic Retention Time (HRT) of 0.2076 days at an hydraulic flow rate of 14.6x10(-3 )m(3)/day and Chemical Oxygen Demand (COD) loading rate of 4.3 kg/m(3)/day. The intermediates that were formed during the yeast fermentation and the anaerobic degradation of DASW were characterized by HPLC, proton NMR, C(13) NMR and mass spectrometry.

Adsorption↗
PubMed1991

Preference of Old World monkeys for amino acids and other gustatory stimuli: the influence of monosodium glutamate.

Monosodium glutamate (MSG) is widely considered to enhance the flavor of beef, chicken, fish, and vegetables. This effect may be due to the interaction of glutamate with free amino acids or other basic taste stimuli present in these foods. A single-bottle test was used in order to test the preference of Old World monkeys for an extended array of gustatory stimuli individually and in combination with MSG. Six male cynomolgus monkeys, maintained on an 18-h water deprivation schedule, were given 30 min access daily to a sapid stimulus or distilled water. The following stimuli (selected on the basis of prior experimentation) were tested alone and in combination with 0.03 M MSG: sucrose, fructose, glucose, maltose, polycose, sodium saccharin, glycine, sodium chloride, hydrochloric acid, tartaric acid, malic acid, citric acid, quinine hydrochloride, urea, and beef broth. The L-isomers of the following free amino acids also were tested: alanine, histidine, phenylalanine, proline, serine, valine. The addition of MSG to the stimuli listed above had no significant effect upon the monkeys' preference or aversion thresholds. Most suprathreshold stimuli that the monkeys neither preferred nor avoided were unaffected by the addition of MSG. The monkeys' preference for sugars was adversely affected in mixtures containing MSG, but other stimuli that humans report to be sweet tasting (alanine, glycine, polycose) were unaffected. The data from the present experiment demonstrate that MSG was capable of altering the monkeys' preference for some but not all of the gustatory stimuli tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1988

Absence of mutagenic activity of acidity regulators in the Ames Salmonella/microsome test.

The activities of various concentrations of 4 acidity regulators (anhydrous citric acid, phosphoric acid, malic acid and lactic acid) used in food industries in Iraq was assayed using the Salmonella/microsome mutagenicity assay. None of the samples was mutagenic in the absence or in the presence of S9 to any of the tester strains of Salmonella typhimurium.

Animals↗
PubMed1985

Rhinovirus inactivation by nasal tissues treated with virucide.

Rhinovirus colds may be transmitted by hand-to-hand contact followed by self-inoculation of nasal and/or conjunctival mucosa with virus contaminating the fingertips. The purpose of this study was to determine whether impregnation of nasal tissues with virucidal compounds could prevent rhinovirus from passing through the tissue and thus provide a means of preventing hand contamination during nose blowing. Paper tissues treated with a combination of citric acid, malic acid, and sodium laruryl sulfate were compared to placebo tissues containing sodium saccharin. Recovery of infectious virus was significantly reduced by passage of the virus-containing medium through virucidal versus placebo tissue (1/18 vs. 17/18 respectively, P less than 0.001, Fisher exact test). The virucidal effect of treated tissues was demonstrated for multiple rhinovirus serotypes suspended in either cell culture medium or nasal mucus. Virus contained in mucus from infected volunteers was also inactivated.

Antiviral Agents↗
PubMed2005

Effects of exogenous organic chelators on phytochelatins production and its relationship with cadmium toxicity in wheat (Triticum aestivum L.) under cadmium stress.

Phytochelatins (PCs) have been proposed as a potential biomarker for metal toxicity. In this study, cadmium (Cd) toxicity, PCs production and their relationship in wheat under Cd stress were examined using various exogenous organic chelator-buffered nutrient solutions. Single Cd stress produced strong toxic effects, as indicated by decreases of growth parameters, high level of lipid peroxidation in leaf and overproduction of PCs in root. Exogenous organic chelators with proper dose more or less reduced Cd toxicity by increasing growth parameters and decreasing lipid peroxidation in leaves. Of organic chelators (EDTA, DTPA, citric acid, malic acid and oxalic acid), EDTA was the most effective in decreasing Cd toxicity in plants, followed by DTPA and citric acid. Simultaneously, the concentrations of Cd-induced PCs in roots decreased, and the greatest decrease was caused by application of EDTA and DTPA. Linearly positive relationships were observed between Cd toxicity and root PCs concentrations under the influences of organic chelators, particularly EDTA, DTPA and citric acid. Furthermore, present results provide stronger evidence that PCs synthesis in plant cells was related to free Cd ion concentrations, not total Cd, and demonstrate that the levels of PCs production in plants correlated well with toxic effects caused by the bioavailable Cd levels.

Biomass↗
PubMed2004

Metabolic fingerprinting of wild type and transgenic tobacco plants by 1H NMR and multivariate analysis technique.

The metabolomic analysis of wild type and constitutive salicylic acid producing tobacco plants (CSA tobacco, Nicotiana tabacum 'Samsun' NN) plants overexpressing salicylate biosynthetic genes was carried out by 1H NMR spectrometry and multivariate analysis techniques. The principle component analysis (PCA) of the 1H NMR spectra showed a clear discrimination between those samples by PC1 and PC2. The discrimination of non-inoculated, TMV-virus inoculated, and systemic leaves or veins could also be obtained by PCA analysis. Major peaks in 1H NMR spectra contributing to the discrimination were assigned as those of chlorogenic acid, malic acid, and sugars. This method allows an efficient differentiation between wild type and transgenic plants without any pre-purification steps.

Chlorogenic Acid↗
PubMed2001

Simultaneous determination of artificial sweeteners, preservatives, caffeine, theobromine and theophylline in food and pharmaceutical preparations by ion chromatography.

A novel ion chromatographic method was proposed for the simultaneous determination of artificial sweeteners (sodium saccharin, aspartame, acesulfame-K), preservatives (benzoic acid, sorbic acid), caffeine, theobromine and theophylline. The separation was performed on an anion-exchange analytical column operated at 40 degrees C within 45 min by an isocratic elution with 5 mM aqueous NaH2PO4 (pH 8.20) solution containing 4% (v/v) acetonitrile as eluent, and the determination by wavelength-switching ultraviolet absorbance detection. The detection limits (signal-to-noise ratio 3:1) for all analytes were below the sub-microg/ml level. Under the experimental conditions, several organic acids, including citric acid, malic acid, tartaric acid and ascorbic acid, did not interfere with the determination. The method has been successfully applied to the analysis of various food and pharmaceutical preparations, and the average recoveries for real samples ranged from 85 to 104%. The levels of all analytes determined by this method were in good agreement with those obtained by the high-performance liquid chromatographic procedure. The results also indicated that ion chromatography would be possibly a beneficial alternative to conventional high-performance liquid chromatography for the separation and determination of these compounds.

Caffeine↗
PubMed2002

Increase of sample load without peak deterioration by careful selection of electrolyte in capillary zone electrophoresis.

In this study it is demonstrated that much higher concentrations of bases dissolved in water can be injected in capillary zone electrophoresis without causing peak deterioration, e.g., peak splitting, if it is the co-ion that buffers instead of the counter-ion. Those findings can be utilised to control peak shapes and in this way an increase in the sample load and indirectly a decrease in the detection limits of impurities in the sample can be obtained. Good results were obtained with 4-aminobutyric and 6-aminocaproic acids as buffering co-ions. Another possibility evaluated successfully was that of using a dibasic acid, malic acid or succinic acid. With an electrolyte containing both succinic acid and 6-aminocaproic acid at pH 4.5, it was possible to load at least 10-20 times more of the test substances imidazole, creatinine or 2-aminopyrimidine dissolved in water than with an electrolyte at the same pH containing acetic acid and tris(hydroxymethyl)aminomethane.

Electrolytes↗
PubMed2000

Simultaneous determination of polycarboxylic acids by capillary electrophoresis with a copper electrode.

The simultaneous determination of polycarboxylic acids including oxalic acid, citric acid, malonic acid, malic acid, tartaric acid, aspartic acid and glutamic acid was achieved by capillary electrophoresis with a copper disk electrode (d = 200 microm). In the system. 0.2 mmol/l cetylpridinium bromide (CPB) was used as an electroosmotic flow (EOF) modifier to reverse the direction of EOF. The effects of the solution pH and CPB concentration on separation were evaluated to achieve the optimum separation conditions. At the working potential of +0.14 V (vs. saturated calomel electrode), the calibration curves for all polycarboxylic acids studied were linear with 2 approximately 3-orders of magnitude and all the detection limits (S/N = 3) were below 15 fmol except malonic acid. Furthermore, the oxalic and citric acids in urine were successfully separated and determined with high sensitivity.

Carboxylic Acids↗
PubMed2000

Gas chromatographic-mass spectrometric analysis of acids and phenols in distilled alcohol beverages. Application of anion-exchange disk extraction combined with in-vial elution and silylation.

A GC-MS protocol for profiling spirits, based on 19 acids and phenolic compounds, has been proposed and evaluated. The method combined a simple preconcentration procedure based on solid-phase (anion-exchange) disk extraction, and in-vial elution and silylation of the analytes. The derivatized extract was directly injected into the GC-MS system. These analytes were: C6, C8, C10, C12 acids, pyruvic acid, 2-furoic acid, succinic acid, fumaric acid, glutaric acid, lactic acid, glycolic acid, malic acid, tartaric acid, citric acid, vanillin, syringaldehyde, coniferaldehyde, vanillic acid and gallic acid. The profiles of six different spirits were found reproducible from day-to-day with <20% RSD for measurements of most of the analytes at different concentrations. Recoveries of individual analytes appear to be affected by the level of tannins in the spirits, and they varied from sample to sample. The method of standard addition was used to quantify age-related analytes. Good linearity of response with correlation coefficients in the range of 0.992-0.999 was obtained. The results of the study indicate that for spirits of the same brand but of different ages, the amounts of these analytes appear to increase with the ageing period.

Acids↗
PubMed2001

Characterization of cigar tobaccos by gas chromatographic/mass spectrometric analysis of nonvolatile organic acids: application to the authentication of Cuban cigars.

A reliable method based on gas chromatographic/mass spectrometric (GC/MS) profiling of nonvolatile organic acids is described for the characterization of cigars. The method involves an aqueous extraction of ground tobacco and selective isolation of the acids by simply stirring strong anion exchange (SAX) disks in the aqueous tobacco extract. The acids are then directly silylated on the disk with N-methyl-N-trimethylsilyl-trifluroacetamide (MSTFA) in acetonitrile in an autosampler vial. Elution of the derivatized acids in situ allows the sample to be directly analyzed by GC/MS without further sample handling. Compared to the conventional disk-extraction technique using a vacuum manifold, this method is much less labor intensive, and is desirable for multiple sample analysis. Nicotinic acid, succinic acid, glyceric acid, malic acid, pyroglutamic acid, threonic acid, citric acid, uracil, and an unidentified acid were reproducibly quantified in tobacco samples. Principal component analysis (PCA) of the acid profiles of the filler tobaccos of 18 Cuban cigars and 31 non-Cuban cigars shows separation of the two groups, indicating that the acid profiles are potentially useful in the authentication of Cuban cigars.

Carboxylic Acids↗
PubMed2002

Stabilization of caffeic acid derivatives in Echinacea purpurea L. glycerin extract.

Recent work has shown that enzymatic degradation and oxidation of cichoric acid and other caffeic derivatives occurs in Echinacea preparations. However, very little is known as to the means of stabilizing these phytopreparations. To stabilize the glycerin extract of Echinacea purpurea, we have evaluated the effects of 3 natural antioxidants (citric acid, malic acid, and hibiscus extract) on the stability of the major caffeic acid derivatives (caftaric acid, caffeic acid, cichoric acid, and 2-O-feruloyl-tartaric acid). Chlorogenic acid, which normally occurs in an ethanol extract of E. purpurea, was not present in the glycerin extract. The caffeic acid derivatives, with the exception of 2-O-feruloyl-tartaric acid, were subject to degradation in the control sample. 2-O-Feruloyl-tartaric acid was stable during the whole testing period. All antioxidant treatments greatly improved the stability of caffeic acid derivatives. Stability was dependent upon the concentration of antioxidant added.

Antioxidants↗