Identification of riboflavinyl -D-glucoside in cat liver

Chromatographic determination of riboflavin and its derivatives in food

Three elution methods on two different reversed-phase C18 columns were developed to determine flavin derivatives in raw egg white, raw egg yolk, egg powder, pasteurised milk, fermented milk products and liver (chicken, calf and pig). Additionally, 11 thin-layer chromatography solvent systems were used to confirm presence of flavins detected in assessed products. It was found that an Alphabond C18 column was not as effective as a Symmetry C18 column. Method A (mobile phase gradient of methanol-0.05 M ammonium acetate, pH 6.0 applied on an Alphabond C18 column) can be used for determination of flavin adenine dinucleotide, flavin mononucleotide, riboflavin 4',5'-cyclic phosphate, riboflavin, 10-formylmethylflavin and 10-hydroxyethylflavin in products that do not contain 7alpha-hydroxyriboflavin. Method B (mobile phase gradient of methanol-demineralized water, on an Alphabond C18 column) can be useful to separate flavin coenzymes from other flavin compounds or to confirm the presence of 7alpha-hydroxyriboflavin and 10-hydroxyethylflavin in analysed samples. Method C (mobile phase gradient of methanol-0.05 M ammonium acetate, pH 6.0, on a Symmetry C18 column) allows separation of all flavins detected in tested products: flavin adenine dinucleotide, flavin mononucleotide, riboflavin 4',5'-cyclic phosphate, riboflavin, 10-formylmethylflavin, 10-hydroxyethylflavin, 7alpha-hydroxyriboflavin, riboflavin-beta-D-galactoside and riboflavin-alpha-D-glucoside.

Chromatographic identification of a new flavin derivative in plain yogurt

The presence of flavin derivatives in plain yogurt was assessed by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). The total amount of flavins in yogurts produced by different companies was variable and oscillated between 150.0 and 218.8 microg/100 g. Riboflavin (RF) was the predominant flavin. Besides RF, flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), 7alpha-hydroxyriboflavin (7alpha-HRF), 4'- or 5'-D-riboflavin-beta-D-galactoside (RFgal), and traces of 10-formylmethylflavin (10-FMF) and 10-hydroxyethylflavin (10-HEF) have been found. It is known that RFgal may be obtained using enzymes or cultures of different microorganisms, but its presence in foodstuffs has not been demonstrated, yet.

Chromatographic determination of flavin derivatives in baker's yeast

The presence of flavin derivatives in baker's yeast was tested by high-performance liquid chromatography and thin-layer chromatography. In yeast samples, besides flavin adenine dinucleotide and flavin mononucleotide, small amounts of riboflavin and traces of 10-formylmethylflavin have been found. Total amount of flavins was calculated to be 17.9 +/- 2.9 micrograms/g of fresh yeast. The distribution of flavin adenine dinucleotide, flavin mononucleotide, riboflavin and 10-formylmethylflavin in total flavin content were estimated to be 71.5%, 25.8%, 1.7% and below 0.05%, respectively. In some samples we have additionally detected small amounts (0.8% of total flavins) of new flavin derivative which has been identified as 4',5'-riboflavin cyclic phosphate by means of its chromatographic and chemical behaviour. This compound seems to be a product of flavin adenine dinucleotide degradation and probably has been earlier mistaken for flavin mononucleotide. Its formation is dependent on pH conditions.

Effect of the tridecamer of compound 48/80, a Ca2+-dependent histamine releaser, on phospholipid metabolism during the early stage of histamine release from rat mast cells

When the tridecamer component of compound 48/80 (Fraction D, Fr.D), a Ca2+-dependent histamine releaser, was incubated with rat mast cells that had been prelabeled with [32P]phosphate, [3H]inositol or [3H]glycerol, it induced a rapid decrease in [32P]phosphatidylinositol-4,5-bisphosphate (PIP2) followed by increases of [3H]inositol-1,4,5-trisphosphate (Ins P3) and [3H]diacylglycerol during the 10 sec prior to detectable histamine release. Fr.D-induced changes of the metabolism of these compounds occurred even in the absence of Ca2+, but to a lesser extent than in the presence of Ca2+. In contrast, the accumulation of [3H]arachidonic acid into phosphatidylcholine (PC), phosphatidylinositol (PI) and phosphatidic acid (PA) in [3H]arachidonic acid-prelabeled mast cells was Ca2+-dependently stimulated by Fr.D with a concomitant decrease in [3H]phosphatidylethanolamine (PE). These Ca2+-dependent changes in PC and PE were not observed in mast cells preloaded with [32P]phosphate, while [32P]PI and [32P]PA increased Ca2+ independently. Fr.D also increased 45Ca2+ uptake by mast cells within 5 sec after the stimulation. These results indicate that Fr.D binding to mast cell Ca2+ independently induces rapid changes of PI cycle-related metabolism of plasma membrane components, while it also induces Ca2+-dependent accumulation of arachidonic acid into PC, PI and PA in association with the decrease of PE, which may be important during the latent period prior to the Ca2+-dependent release of histamine from Fr.D-stimulated mast cells.