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At least 109 records · Page 6Linked to original sources
PubMed2005

Immunoglobulins can utilize riboflavin (Vitamin B2) to activate the antibody-catalyzed water oxidation pathway.

We have recently discovered a reaction that all antibodies, regardless of source or antigenic specificity can catalyze, that is the reaction between singlet dioxygen ((1)O(2)(*)) and H(2)O to generate H(2)O(2). We have named this process the antibody-catalyzed water oxidation pathway (ACWOP). As part of our ongoing investigations into the possible biological role of this pathway, we have studied whether isoalloxazine-containing cofactors, that are known to be endogenous photosensitizers via Type-II pathways to generate (1)O(2)(*), such as riboflavin (RF, Vitamin B2) can trigger the ACWOP. Herein we show that regardless of the antigenic specificity or heavy and light chain composition, all antibodies and their fragments are able to intercept the (1)O(2)(*) generated by photo-oxidation of RF in the presence of oxygen (ambient aerobic conditions) to activate the ACWOP. The initial rate of HOOH generation by a panel of murine antibodies ranges from 0.218 to 0.998 microM/min. The initial rate of antibody-catalyzed HOOH production is accelerated in D(2)O and is quenched in NaN(3), highlighting the key intermediacy of (1)O(2)(*) in the process. Critically, the ACWOP is photo-activated at physiologically relevant concentrations of RF (<50 nM) suggesting that this pathway may be relevant in an in vivo setting. Finally, when activated by RF the ACWOP generates oxidants that accelerate the hemolysis of sheep RBCs hinting at a pathophysiological effect of this RF-induced photo-oxidation pathway.

Animals↗
PubMed2002

Photodynamic occlusion of ocular neo-vascularization with B2 vitamin.

Photodynamic therapy (PDT) of cancer has been known for over twenty years and is based on the dye-sensitized photooxidation of different biological targets in the tumoral tissue yielding to a photochemically induced cell's death via apoptotic pathways. Several parameters affect clinical trials in PDT and influence the therapeutic outcome. A potentially major application of PDT in a non-cancer field is its use in treatment of age-related macular degeneration. This condition, caused by proliferation of neovasculature in the retina, is the major cause of blindness in the over 50s. Using a photosensitiser which enters neovasculature very rapidly following administration and is subsequently quickly moved from the circulation. Ocular neovascular disease represents an important cause of blindness today. In this paper, was used an animal model (rabbit) to evaluate the vaso-occlusive potential of photodynamic therapy with B2 vitamin. Neovascularization induced in the rabbit cornea consists of an easily accessible monolayer-like neovascular net within a transparent matrix. This fact allows studying the efficiency of occlusion in an isolated neovascular structure.

Animals↗
PubMed1996

Microtitre-plate enzyme-linked ligand-sorbent assay of riboflavin (vitamin B2) in human plasma and urine.

Enzyme-linked ligand-sorbent assay (ELLSA) of riboflavin was performed in standard, multi-well microtitre plates. 3-Carboxymethylriboflavin was carbodiimide-coupled to bovine serum albumin and the conjugate was adsorbed on the well surface. Riboflavin-binding protein from egg-white was biotinylated with biotinamidocaproate N-hydroxysuccinimide ester. The assay was based on competition of riboflavin analyte with the immobilized flavin for the biotinylated binder. Secondary adsorption of the biotinylated riboflavin-binding protein was measured by using avidin-bearing horseradish peroxidase label. The optimized method had a detection limit of 0.8 pmol of riboflavin and was expected to work within a riboflavin concentration range of 2 X 10(-8)(-4) X 10(-6) mol l-1. Preliminary trials suggested that ELLSA was suitable for determining riboflavin in human urine and the sum of riboflavin and flavin nucleotides in human plasma. The analytical performance of ELLSA for those materials was characterized by good consistency of the results with those obtained by conventional, fluorimetric methods, a mean recovery of riboflavin supplement of over 90% and a within-plate relative standard deviation below 20%. Some unique samples of both urine and plasma were assayed with between-plate relative standard deviations higher than 30%, implicating further modification of this version of ELLSA. The method intended for routine control determinations of vitamin B2 status in human subjects and is addressed to laboratories that routinely perform automated, microplate-based enzyme-linked assays.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

[Assessment of vitamin B2, B6, and PP supply from data on excretion of vitamins and their metabolites in alimentary iron and riboflavin deficiency].

Alimentary deficiency in riboflavin and/or iron in rats involved distinct decrease in excretion of 4-pyridoxylic acid and 1-N-methyl nicotinamide--the metabolites considered as the indices of vitamins B6 and PP consumption. The effect observed appears to occur due to a decrease in activity of some iron- and flavin-containing enzymes participating in the metabolism of pyridoxine and niacin. Addition to the diet of the deficient component normalized these patterns. Use of the data on excretion of 4-pyridoxylic acid and 1-N-methyl nicotinamide as criteria of consumption of pyridoxine and niacin is discussed.

Animals↗