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 253 records · Page 14Linked to original sources
PubMed2002

Hydrophilic carboxylic acids and iridoid glycosides in the juice of American and European cranberries (Vaccinium macrocarpon and V. oxycoccos), lingonberries (V. vitis-idaea), and blueberries (V. myrtillus).

Analysis of the hydrophilic fraction of cranberry juice by reversed-phase HPLC using an Aqua LUNA column with diode array or MS detection revealed the presence of quinic acid, malic acid, shikimic acid, and citric acid. For the first time, two iridoid glucosides were found in the juice. The two iridoid glucosides were shown to be monotropein and 6,7-dihydromonotropein by MS and NMR spectroscopy. A fast reversed-phase HPLC method for quantification of the hydrophilic carboxylic acids was developed and used for analyses of cranberry, lingonberry, and blueberry juices. The level of hydrophilic carboxylic acids in cranberries was 2.67-3.57% (w/v), in lingonberries 2.27-3.05%, and in blueberries 0.35-0.75%. In lingonberries both iridoid glucosides were present, whereas only monotropein was present in blueberries.

Beverages↗
PubMed2004

1H NMR studies on Italian balsamic and traditional balsamic vinegars.

In the present work Principal Component Analysis applied to (1)H NMR spectra of balsamic and traditional balsamic vinegars is used to establish a simple and rapid aging determination protocol. Chemical composition of vinegar is dominated by carbohydrates even though several small components can be clearly observed in the proton NMR spectrum. Quantitative determination of some selected metabolites such as ethanol, acetic acid, malic acid, glucose, and HMF, considered as potential aging indicators, has been performed. (1)H NMR spectroscopy provides noninvasive characterization of such compounds, and our data demonstrate the validity of this approach, giving very promising results for assessing the quality of the final product.

Acetic Acid↗
PubMed2006

Comparison of cardioprotective abilities between the flesh and skin of grapes.

Recent studies have documented that grapes and grape juices are equally cardioprotective as red wine. The existing reports implicate that the skin and seeds of the grapes containing polyphenolic antioxidants are instrumental for the cardioprotective properties of grapes. The present study examines if the flesh of grapes also possesses any cardioprotective abilities. Three groups of randomly selected rats were fed, water only (control), flesh of the grapes (2.5 mg/kg b. wt.) or the skins (2.5 mg/kg b. wt.) for 30 days. At the end of the 30 days, isolated perfused hearts were made ischemic for 30 min followed by 2 h of reperfusion in the working mode. The results demonstrated that both flesh and skin of the grapes could protect the hearts from ischemic reperfusion injury as evidenced by improved postischemic ventricular recovery and reduced myocardial infarct size. High performance liquid chromatography (HPLC) revealed that skin and flesh contained comparative amounts of glucose, fructose, tartaric acid, malic acid, shikimic acid, and trans-caftaric acid. In addition, the flesh contained reduced amounts (compared to skin) of cis-coutaric, trans-coutaric, caffeic, p-coumaric, cinnamics, and catechin/epicatechin. Total polyphenolic index was also lower in flesh compared to skin. The anthocyanins were present exclusively in the skin. Electron paramagnetic resonance (EPR) spectrometry of hydroxy radicals indicated that both flesh and skins possessed equal amount of ROS scavenging activities. Total malonaldehyde content in the heart was reduced comparatively with either flesh or skin. The results indicate for the first time that the flesh of grapes are equally cardioprotective as skin, and antioxidant potential of skin and flesh of grapes are comparable with each other despite of the fact that flesh does not possess any anthocyanin activities.

Animals↗
PubMed1999

Mumefural, citric acid derivative improving blood fluidity from fruit-juice concentrate of Japanese apricot (Prunus mume Sieb. et Zucc).

The effects of food components on blood fluidity were studied by in vitro assay using a dedicated microchannel instrument for model capillaries. We found that the fruit-juice concentrate of the Japanese apricot (Prunus mume Sieb. et Zucc), a traditional Japanese food, markedly improved the fluidity of human blood. Using HPLC, we isolated the active compounds and characterized them using UV, MS, IR, and NMR. They included a novel compound, 1-[5-(2-formylfuryl)methyl] dihydrogen 2-hydroxypropane-1,2, 3-tricarboxylate (mumefural), and a related compound, 5-hydroxymethyl-2-furfural (HMF). Mumefural markedly improved blood fluidity in all subjects, while HMF worked differently in different individuals. The flow rate of blood spiked with mumefural or HMF was compared to that of the two predominant organic acids in the fruit. Citric acid, malic acid, and furfuryl alcohol also improved fluidity in all subjects. The activity of P. mume is derived from not only artifacts produced during thermal processing, such as mumefural, but also from endogenous organic acids.

Beverages↗
PubMed1999

Chemistry, biochemistry, nutrition, and microbiology of lysinoalanine, lanthionine, and histidinoalanine in food and other proteins.

Heat and alkali treatments of foods, widely used in food processing, result in the formation of dehydro and cross-linked amino acids such as dehydroalanine, methyldehydroalanine, beta-aminoalanine, lysinoalanine (LAL), ornithinoalanine, histidinoalanine (HAL), phenylethylaminoalanine, lanthionine (LAN), and methyl-lanthionine present in proteins and are frequently accompanied by concurrent racemization of L-amino acid isomers to D-analogues. The mechanism of LAL formation is a two-step process: first, hydroxide ion-catalyzed elimination of H(2)S from cystine and H(2)O, phosphate, and glycosidic moieties from serine residues to yield a dehydroalanine intermediate; second, reaction of the double bond of dehydroalanine with the epsilon-NH(2) group of lysine to form LAL. Analogous elimination-addition reactions are postulated to produce the other unusual amino acids. Processing conditions that favor these transformations include high pH, temperature, and exposure time. Factors that minimize LAL formation include the presence of SH-containing amino acids, sodium sulfite, ammonia, biogenic amines, ascorbic acid, citric acid, malic acid, and glucose; dephosphorylation of O-phosphoryl esters; and acylation of epsilon-NH(2) groups of lysine. The presence of LAL residues along a protein chain decreases digestibility and nutritional quality in rodents and primates but enhances nutritional quality in ruminants. LAL has a strong affinity for copper and other metal ions and is reported to induce enlargement of nuclei of rats and mice but not of primate kidney cells. LAL, LAN, and HAL also occur naturally in certain peptide and protein antibiotics (cinnamycin, duramycin, epidermin, nisin, and subtilin) and in body organs and tissues (aorta, bone, collagen, dentin, and eye cataracts), where their formation may be a function of the aging process. These findings are not only of theoretical interest but also have practical implications for nutrition, food safety, and health. Further research needs are suggested for each of these categories. These overlapping aspects are discussed in terms of general concepts for a better understanding of the impact of LAL and related compounds in the diet. Such an understanding can lead to improvement in food quality and safety, nutrition, microbiology, and human health.

Alanine↗
PubMed2002

A mid-IR flow-through sensor for direct monitoring of enzyme catalysed reactions. Case study: Measurement of carbohydrates in beer.

A novel mid-IR flow-through sensor for in situ monitoring of the enzymatic reaction of amyloglucosidase with carbohydrates was developed. Amyloglucosidase was immobilised on agarose beads with N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and directly placed in a conventional IR flow-through cell. The carbohydrate content of various beer samples was then determined by following the enzymatic hydrolytic cleavage of carbohydrates to glucose with Fourier-transform infrared (FTIR) spectroscopy. The whole procedure was done in an automated way operating in the stopped flow mode by incorporating the flow-through sensor in a sequential injection (SI) manifold. As the immobilised enzyme was directly probed by the IR beam, an in situ study of the enzymatic reaction was possible enabling determination of the Michaelis-Menten constant of the immobilised enzyme. A linear calibration curve was recorded using maltose standards in the range between 0.86 and 7.13 g L(-1). The proposed method was successfully applied to the determination of the carbohydrate content of four different beer samples by the standard addition method. Moreover experiments showed the possibility of monitoring in situ the immobilisation of the enzyme as well as a small organic acid (malic acid) on the agarose beads using EDC.

Journal Article↗
PubMed1989

Calcium bioavailability and iron-calcium interaction in orange juice.

We have determined the effects of orange juice on calcium bioavailability from CCM (a combination of CaCO3, citric acid, malic acid, 5:1:1, mol/mol/mol) and iron-calcium interaction by using whole body isotope retention techniques in rats. The mean calcium retention values from CCM were 42.8% from orange juice and 33.0% from water, a control. Orange juice significantly (p less than 0.05) improved calcium bioavailability. This enhancement of calcium absorption is independent of orange juice's pH and citric acid. Iron absorption from orange juice with CCM (36.7%) was also significantly higher than that from control (water) plus CCM (12.3%). Ascorbic acid at levels naturally present in orange juice failed to improve iron retention (12.3% vs 12.5%) from water plus CCM. In contrast, citric acid (at orange juice level) significantly (p less than 0.05) promoted iron absorption in the presence of CCM (8.0% vs 23.7%). The benefit of citric acid on iron-calcium interaction is enhanced by ascorbic acid. In the presence of both citric acid and ascorbic acid, at orange juice levels, iron absorption from water plus CCM (37.6%) was comparable to that from water without CCM (34.5%). These results show orange juice can deliver bioavailable calcium from CCM with minimal inhibition of iron absorption. Citric acid and ascorbic acid are likely the major orange juice components that contribute to the alleviation of iron absorption inhibition by CCM.

Absorption↗
PubMed2005

Time-intensity evaluation of acid taste in subjects with saliva high flow and low flow rates for acids of various chemical properties.

The role of the chemical properties of sour stimuli and the role of the human saliva flow rate on acid perception were investigated in 11 high saliva flow rate (HF) and 11 low saliva flow rate (LF) subjects with a continuous stimulus delivery flow rate of 3.2 ml/min and using the time-intensity technique for perception recording. Continuously measuring the pH on the tongue surface on three HF and three LF subjects showed that HF subjects' saliva decreased the acidity of the acid solution more efficiently than the LF subjects' saliva did. However, HF subjects exhibited higher perceived intensity for acid solutions than LF subjects. At equal pH, the order of the efficiency of acids indicated that HCl was the least efficient acid stimulus and acetic acid the most efficient. At equal concentration, the order of efficiency was the opposite (citric acid > malic acid > lactic acid > acetic acid), indicating that titratable acidity rather than pH has to be considered when comparing weak acids. At high concentrations, the ratio of relative efficiency is more in favor of the hydrophobic than the hydrophilic acid in HF subjects compared with LF subjects, i.e. HF subjects are more sensitive to hydrophobic stimuli. Hydrophobic molecules may diffuse more easily into the epithelium of HF than LF subjects, and reach more efficiently trigeminal nerve endings in addition to taste receptor cells.

Acetic Acid↗
PubMed1992

Determination of vitamin C and organic acids in various fruits by HPLC.

Liquid chromatographic methodology for determination of vitamin C and organic acids in different fruits (whortleberry, blackberry, red currant, black currant, raspberry, babaco, feijoa, kiwano, passion fruit, red and yellow tamarillos, medlar, and persimmon) cultivated in Galicia, Spain are developed. Both methods use a C18 column and an RP-18 precolumn for the stationary phase. High-performance-liquid-chromatographic-(HPLC-) grade water is brought to pH 2.2 with sulphuric acid for the mobile phase. The flow rate is 0.4 mL/min, and UV detection is at 254 nm for vitamin C and 214 nm for organic acids. Coefficients of variation of 1.84, 1.20, 1.00, and 2.60% are obtained for the vitamin C, quinic acid, malic acid and citric acid, respectively.

Ascorbic Acid↗
PubMed1980

Photosynthetic formation of the aspartate family of amino acids in isolated chloroplasts.

The metabolism of (14)C-labeled aspartic acid, diaminopimelic acid, malic acid and threonine by isolated pea (Pisum sativum L.) chloroplasts was examined. Light enhanced the incorporation of [(14)C] aspartic acid into soluble homoserine, isoleucine, lysine, methionine and threonine and protein-bound aspartic acid plus asparagine, isoleucine, lysine, and threonine. Lysine (2 millimolar) inhibited its own formation as well as that of homoserine, isoleucine and threonine. Threonine (2 millimolar) inhibited its own synthesis and that of homoserine but had only a small effect on isoleucine and lysine formation. Lysine and threonine (2 millimolar each) in combination strongly inhibited their own synthesis as well as that of homoserine. Radioactive [1,7-(14)C]diaminopimelic acid was readily converted into [(14)C]threonine in the light and its labeling was reduced by exogenous isoleucine (2 millimolar) or a combination of leucine and valine (2 millimolar each). The strong light stimulation of amino acid formation illustrates the point that photosynthetic energy is used in situ for amino acid and protein biosynthesis, not solely for CO(2) fixation.

Journal Article↗
PubMed1976

The availability of folates in man: effect of orange juice supplement on intestinal conjugase.

The mechanisms of the low availability of endogenous folates in orange juice and the inhibitory effects on the availability of pteroylheptaglutamate (PteGlu7) caused by orange juice supplements were investigated in man by the use of simulated orange juice (containing the principal components: citric acid, malic acid, etc.) with several different pHs. The endogenous folates in orange juice were identified as mainly 5-methyl reduced derivatives of pteroylpolyglutamates (40-45% pentaglutamate, 10-15% tetraglutamate, 30-40% monoglutamate, and the rest were tri-and diglutamates). The availability of PteGlu7 is decreased to 54% by supplementation with 600 g concentrated orange juice (pH 3.7) and to 39% and 66% by the supplement of 24 g and 12 g citric acid (pH 3.7), respectively. Neutralization of 12 g citric acid to pH 6.4 largely reverses the inhibitory effect. On the other hand, the availability of pteroylmonoglutamate (PteGlu) is not influenced by a supplement of orange juice or citric acid. The results suggest that the low availability of PteGlu7 is due to the inhibition of intestinal conjugase caused by the low pH. These observations suggest that pH of foodstuffs may be an important factor in the absorption of polyglutamate forms of folate.

Adult↗
PubMed2005

Production of alternatives to fuel oil from organic waste by the alkane-producing bacterium, Vibrio furnissii M1.

AIMS: We investigated the production of alternatives to fuel oil through the bacterial metabolism of organic waste. The availability for this purpose of various sources of organic waste for hydrocarbon production by the alkane-producing bacterium, Vibrio furnissii M1, was examined. METHODS AND RESULTS: We screened 17 authentic compounds which can generally be found in organic waste for their hydrocarbon production. Carbon (3 mmol) in a 50-ml culture with acetic acid, lactic acid, butyric acid, succinic acid, malic acid, pentanoic acid, hexanoic acid glucose, xylose, starch or sucrose yielded 10-27 mg of alkanes or alkenes. The chain length of these alkanes or alkenes varied according to the culture from C14 to C27. Varying the ratio of carbon to nitrogen in the culture had no effect on the hydrocarbon production. Crude blackstrap molasses were also converted into alkanes with a conversion ratio of 20% (half of that in an authentic sucrose medium) of the total carbon consumption. CONCLUSIONS: V. furnissii M1 could produce hydrocarbons corresponding to kerosene or light oil from volatile fatty acids and sugars. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on bacterial hydrocarbon production from organic waste.

Alkanes↗
PubMed2006

Lactobacillus casei metabolic potential to utilize citrate as an energy source in ripening cheese: a bioinformatics approach.

AIMS: To identify potential pathways for citrate catabolism by Lactobacillus casei under conditions similar to ripening cheese. METHODS AND RESULTS: A putative citric acid cycle (PCAC) for Lact. casei was generated utilizing the genome sequence, and metabolic flux analyses. Although it was possible to construct a unique PCAC for Lact. casei, its full functionality was unknown. Therefore, the Lact. casei PCAC was evaluated utilizing end-product analyses of citric acid catabolism during growth in modified chemically defined media (mCDM), and Cheddar cheese extract (CCE). Results suggest that under energy source excess and limitation in mCDM this micro-organism produces mainly L-lactic acid and acetic acid, respectively. Both organic acids were produced in CCE. Additional end products include D-lactic acid, acetoin, formic acid, ethanol, and diacetyl. Production of succinic acid, malic acid, and butanendiol was not observed. CONCLUSIONS: Under conditions similar to those present in ripening cheese, citric acid is converted to acetic acid, L/D-lactic acid, acetoin, diacetyl, ethanol, and formic acid. The PCAC suggests that conversion of the citric acid-derived pyruvic acid into acetic acid, instead of lactic acid, may yield two ATPs per molecule of citric acid. Functionality of the PCAC reductive route was not observed. SIGNIFICANCE AND IMPACT OF THE STUDY: This research describes a unique PCAC for Lact. casei. Additionally, it describes the citric acid catabolism end product by this nonstarter lactic acid bacteria during growth, and under conditions similar to those present in ripening cheese. It provides insights on pathways preferably utilized to derive energy in the presence of limiting carbohydrates by this micro-organism.

Acetic Acid↗
PubMed1969

Growth and sporulation of Bacillus subtilis mutants blocked in the pyruvate dehydrogenase complex.

Two "ACE" mutants of Bacillus subtilis which require acetate for growth on glucose minimal medium have been isolated. They do not grow with acetoin, 2,3-butanediol, fatty acids, isoleucine, lipoic acid, malic acid, pyruvic acid, succinic acid, thiamine, or valine, but respond somewhat to glutamate or citrate. The mutants lack the activity of the pyruvate dehydrogenase complex; they excrete pyruvate and later acetoin. They grow in nutrient sporulation medium (NSMP) to one-half the normal turbidity and do not sporulate subsequently. When acetate is added to NSMP (at the optimal concentration of 0.07 m), the ACE mutants grow to the normal turbidity and then sporulate normally. Growth but not sporulation is restored in NSMP upon addition of 2,3-butanediol, citrate, glucose, glutamate, glycerol, or ribose, but not upon addition of acetoin, malate, oxaloacetate, pyruvate, and several other compounds. After growth in NSMP has stopped, the mutants incorporate uracil only at a very low rate, which can be increased by the addition of acetate, citrate, or glutamate. Furthermore, the metabolism of acetoin is prevented after growth has stopped but can be restored by the addition of acetate. All these results can be explained by a lack of reduced nicotinamide adenine dinucleotide (NADH) resulting from the deficiency in acetylcoenzyme A. In fact, after growth of the ACE mutants had stopped, the NADH concentration was at the borderline of measurability, whereas it increased significantly upon addition of glucose. The growing standard strain contains, at the same bacterial turbidity, at least 20 times more NADH (230 pmole/optical density unit at 600 nm) than the nongrowing ACE mutants. The isolated spores, obtained after growth in NSMP plus acetate, can be initiated to germinate in the presence of either l-alanine or the combination of l-asparagine, fructose, glucose, and potassium; addition of acetate is not required and has no effect.

Acetates↗
PubMed1996

New biodegradable oligoesters for pharmaceutical application.

Tartaric acid, malic acid, and glyceric acid were copolycondensed with glycolic acid at various molar ratios in feed to quickly synthesize biodegradable oligoesters. They were likely to have a moderately cross-linked structure with relatively low molecular weights and hydrophilic groups on the chains. In addition to macroscopic gels which were insoluble in any solvents, we could obtain the oligoesters which were insoluble in water but soluble in N,N-dimethylformamide. The degradation rate of the oligoesters was higher than that of lactic acid (LA) oligomers having molecular weights of a few thousands. On the contrary, their glass transition and flow temperatures were much higher than those of LA oligomers, indicating that their handling during the preparation of drug delivery dosage forms was much improved. The formulation of microspheres containing drugs from the oligoesters revealed that they were useful as biodegradable matrices having high degradation rates.

Antineoplastic Agents↗
PubMed1969

Study on the (14)C-glucose metabolism by Clonorchis sinensis: Paper Chromatographic Analyses in Combination with Autoradiography.

Radioactive (14)C-glucose(U) was given to Clonorchis sinensis in Tris buffer medium, in corder to trace the metabolic fate of the labelled carbon. The labelled carbon from glucose enters into intermediary metabolites and end products of anaeroblic glycolysis, Embden-Meyerhof pathway, and of aerobic Krebs cycle. These product were identified by one or two-dimensional paper chromatography in combination with autoradoigraphy. 1)The labelled metabolites detected in this experiment corresponded to pyruvic acid, latic acid, malic acid, succinic acid and fumaric acid. 2)Amino acids, such as alanine, aspartic acid, glutamic acid, valine, theronine, and serine, derived by the degradation of (14)C- glycose were also found. 3)Labelled compounds behaving like alanine, aspartic acid and glutamic acid were observed in the chroma to gram of incubation medium. 4)The preciptation which suggests a positive reaction for protein occured when absolute ethanol was added to the incubation medium.

Journal Article↗
PubMed1982

Characterization of cerebral cysteine sulfinic acid decarboxylase. Molecular parameters and inhibition studies.

The molecular properties of cysteine sulfinic acid decarboxylase (EC 4.1.1.29) from calf brain were examined in a crude enzyme preparation. The Stokes radius (42 A) was determined by gel filtration and the sedimentation coefficient, s20,w (6.1 x 10(-13 s) by density gradient centrifugation. Calculation of the molecular weight and frictional ratio gave values of 73,000 and 1.52, respectively. beta-Mercaptopropionic acid and an arginine reagent, phenylglyoxal, were observed to be potent inhibitors of the enzyme. Pyridoxal phosphate, a cofactor of the decarboxylase, was observed to protect the enzyme against phenylglyoxal inhibition. This result indicates that an arginine residue may be located at the active site of cysteine sulfinic acid decarboxylase. The components of taurine metabolism gave little or no inhibition of the decarboxylase. Glutaric acid, malic acid and C-allylglycine, all widely known as potent inhibitors of glutamic acid decarboxylase, only slightly inhibited cysteine sulfinic acid decarboxylase.

3-Mercaptopropionic Acid↗
PubMed2001

[Simultaneous determination of various food additives by high performance liquid chromatography].

A novel method is proposed for the simultaneous separation and determination of eight food additives, acesulfame potassium (AK), aspartame (ASP), benzoic acid (BA), caffeine (CA), saccharin sodium (SA), sorbic acid (SOR), theobromine (TB) and theophylline (TP) by reversed-phase high performance liquid chromatography. The separation was achieved within 23 min by using an Alltech Econosphere C18 column with 10 mmol/L NaH2PO4(pH 4.00)-acetonitrile (90:10, V/V) as mobile phase. The qualification and quantitation were accomplished by using a photodiode array detector. The detection limits (S/N = 3) for all analytes were below mg/L level. Under the experimental conditions, other common food additives and organic acids such as cyclamate, 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 foods as well as pharmaceutical preparation, and the average recoveries for real samples ranged from 78.5% to 107.2%.

Benzoic Acid↗