Vitamin B6 Related Compounds Research Articles

A comparative study of the electrochemical properties of vitamin B-6 related compounds at physiological pH

A comparative study of vitamin B6 group and related compounds in buffered solutions using electrochemical techniques has been performed at neutral pH. Irreversible bi- or tetra-electronic processes are observed for these substances, and the electron transfer coefficient (αn) calculated. It was concluded that either the first or second election transfer were the rate determining step of the electrode process. The diffusion coefficient of these substances was calculated and the values given follow an inverse tendency to the molecular size. For aldehydes the values obtained were corrected of the hydration reaction. It is important to remark that catalytic waves were reported for the first time for these compounds. Using a model involving the nitrogen of the basic structure the kinetic constants were calculated for most of them.

Spectroscopic Properties of 4‐Pyridoxic Acid as a Function of pH and Solvent

AbstractThe photophysical properties and acid/base equilibria of 4‐pyridoxic acid (=3‐hydroxy‐5‐(hydroxymethyl)‐2‐methylpyridine‐4‐carboxylic acid), the final product of the catabolism of vitamin B6, have been studied in aqueous solutions. The ground state of 4‐pyridoxic acid exhibits the different protonated forms A–D in the range of H0=−6 to pH 11.5. HMQC‐ and HMBC‐NMR Studies allowed the pH‐dependent assignment of the different C‐atoms, and the evaluation of the deprotonation sequence. The 3‐OH group in the ground state has a ‘pKa’ of H0=−0.64, which is much lower than that found for other vitamin B6 related compounds. The pKa value of the 4‐COOH group is 5.4. Fluorescence studies showed that the same species exist at the lowest excited singlet state, but in different pH ranges. The 3‐OH group is four pH units more acidic in the lowest excited singlet state than in the ground state. Excitation spectra and emission decays in the pH range of 8 to 11.5 indicate that the pyridine N‐atom is more basic in the excited singlet state than in the ground state. The emission spectra are red‐shifted in protic solvents, in agreement with an intramolecular H‐bond between the ionized 3‐OH group and the nonionized 4‐COOH group.

Determination of Vitamin B6 Compounds in Foods Using Liquid Chromatography with Post-Column Derivatization Fluorescence Detection

The liquid chromatographic determination of six vitamin B6-related compounds, the three B6 vitamers, their corresponding phosphorylated esters, and an excretion product, is optimized using the reversed-phase technique with a stationary phase based on a ligand with amide groups and the endcapping of trimethylsilyl. The isocratic mobile phase consisted of a phosphate buffer, and fluorescence detection involved a post-column derivatization reaction using sodium hydrogensulphite to enhance the fluorescence of the phosphate ester. Peaks were identified by the retention characteristics and fluorescence spectra. Detection limits ranged from 1–25 ng mL−1. Two extraction procedures using acid hydrolysis and enzymatic hydrolysis were compared. The method was applied to the determination of B6 vitamin derivatives in different types of food including beef liver, egg yolk, baby food cereals and honey. The natural free vitamers appeared in honey and baby food cereals, while the phosphorylated esters were found in the foods of animal origin. An assay using two certified reference materials gave results within the certified range.

Water-Soluble Vitamins

Water-Soluble Vitamins

Pyridoxal 5′-Phosphate is an ATP-Receptor Antagonist in Freshly Isolated Rat Cardiomyocytes

Although extracellular ATP is considered to exert a positive inotropic action on the myocardium through purinoceptors, very little information is available regarding interventions which may modify the actions of ATP on the heart. We report here that pyridoxal 5′-phosphate (PLP), an active form of vitamin B6, shows antagonism towards ATP-induced positive inotropic effect in isolated perfused rat hearts, ATP-induced increase in [Ca2+] in freshly isolated adult cardiomyocytes and ATP-binding in cardiac sarcolemma; ED50for PLP in each of these cases varied from 10–15μm . PLP (5–50μm) was observed to antagonize the positive inotropic effect of ATP but did not modify the action of isoproterenol in the isolated perfused heart. Preincubation of cardiomyocytes with 1–50μm PLP prevented the ATP-induced increase in [Ca2+]iin a concentration-dependent manner but showed no effect on the KCl-induced increase in [Ca2+]i. Creatine phosphate and Na2HPO4as well as vitamin B6-related compounds, such as pyridoxine, pyridoxal, 4-deoxypyridoxine and isonicotinic acid hydrazide showed no effect on the ATP-induced increase in [Ca2+]iin cardiomyocytes. Furthermore, different concentrations of PLP (1–50μm) were shown to inhibit the specific ATPγS binding at both the high and low affinity sites in the cardiac sarcolemmal membrane; adrenoceptor and Ca2+-channel inhibitors did not affect the ATP-binding. It is concluded that PLP may antagonize the actions of ATP on the heart in a selective manner and both pyridoxal and phosphate moieties are essential for its action. Furthermore, it is suggested that PLP may serve as a valuable tool for monitoring the role of purinoceptors in cellular function.

HPLC analysis of vitamin B6 in foods

The objective of this work was to evaluate the methods for determination of vitamin B6 in foods. To achieve this, the literature review focused on sample treatment and liquid chromatographic analysis of vitamin B6 related compounds. In the experimental part, the chosen sample pretreatment and the high-performance liquid chromatographic (HPLC) method were validated, and used to produce vitamin B6 data on various food items commonly consumed in Finland. The main emphasis of the sample treatment was on the extraction efficiency and the maintenance of the original concentration profile of the vitamers. Several acid extraction procedures were tested for this purpose. Perchloric acid was chosen as the extraction agent. Routine food analysis was then performed using dilute ice-cold perchloric acid extraction followed by an internally standardized ion-paired reversed-phase liquid chromatography. Food samples were hydrolyzed with takadiastase and alkaline phosphatase enzymes, phosphorylated and glycosylated vitamers were quantitated before and after the enzymatic digestion. This procedure enabled the extraction of vitamin B6 compounds in their intact forms, and the measurement of free, phosphorylated and glycosylated forms. The maintenance of the concentration profile of the vitamers was verified by using 14C -labeled pyridoxal 5'-phosphate in the examination of the extraction procedure. The extraction efficiency and laboratory performance were confirmed by interlaboratory studies. Up-to-date data on vitamin B6 content of about fifty common food items was produced. The data includes the results from meat and poultry, fish and fish product, dairy product, cereal and vegetable, and ready-to-eat food samples. Free and phosphorylated vitamin B6 compounds were measured in all food groups, and the glycosylated vitamer fraction was analyzed in all plant-derived foods. The results obtained in this work showed that vitamin B6 content of nearly all foods of plant origin was mainly comprised of glycosidically bound pyridoxine derivatives. These bound analytes are normally not taken into account in traditional analytical methods, and food composition tables lack the data of glycosylated pyridoxine. The role of the glycosylated pyridoxines need to be clarified in terms of their analytical and physiological nature. If, as it is currently assumed, the availability of the bound forms is limited for humans, the role of vegetables, cereals and other foods of plant origin as a source of vitamin B6, as well as the analytical methods should be reassessed.;

Transition-metal complexes of vitamin B6 related compounds. 3. X-ray, Moessbauer, and magnetic properties of a binuclear iron(III) complex containing an unusual pyridoxal derivative

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransition-metal complexes of vitamin B6 related compounds. 3. X-ray, Moessbauer, and magnetic properties of a binuclear iron(III) complex containing an unusual pyridoxal derivativeGary J. Long, James T. Wrobleski, Raju V. Thundathil, Don M. Sparlin, and Elmer O. SchlemperCite this: J. Am. Chem. Soc. 1980, 102, 19, 6040–6046Publication Date (Print):September 1, 1980Publication History Published online1 May 2002Published inissue 1 September 1980https://doi.org/10.1021/ja00539a011RIGHTS & PERMISSIONSArticle Views149Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (837 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Transition-metal complexes of vitamin B6 related compounds. 1. Synthesis and electronic and structural properties of several divalent first-row transition-metal complexes of pyridoxylideneamino acids

Transition-metal complexes of vitamin B6 related compounds. 1. Synthesis and electronic and structural properties of several divalent first-row transition-metal complexes of pyridoxylideneamino acids