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A postulated capability of riboflavin and flavin mononucleotide to protect DNA from damage by far-ultraviolet irradiation was investigated in purified reaction mixtures and in cultured mammalian cells. Purified calf thymus DNA, admixed with flavin at approximately physiological ratios, was protected from undergoing irradiation-induced changes in spectral absorbance and viscosity compatible with those accompanying pyrimidine dimerization. Irradiation-induced changes in unprotected DNA were reversed by a subsequent treatment of the DNA with flavin in the presence of visible light. There was no apparent interaction between flavin and non-irradiated DNA. These results suggest that photoexcited flavin interacts directly with the ultraviolet photoproduct in DNA and does not function simply as an energy sink to dissipate photons absorbed by DNA. Cultured embryonic hamster cells were protected from ultraviolet-induced inhibition of growth by a preliminary exposure to relatively large amounts of flavin. This effect was not due to a vitamin- like promotion of cell growth by the flavin. The observation that flavin concentrated transiently in the cytoplasm of exponentially growing hamster cells during a 6 hr incubation period suggested that a shielding action may cooperate with the protective photochemical mechanism in vivo. It was concluded that flavins may function physiologically to protect the genetic material of tissues exposed to actinic radiations, and that when flavin levels in these tissues are inadequate, either because of nutritional deficiency or excessive intensity of irradiation, the damage which results may provide one pathogenetic avenue for the characteristic integumentary lesions of riboflavin deficiency disease. [ABSTRACT FROM AUTHOR]

The rate for photoreduction of riboflavin 5′-phosphate is faster than flavin-adenine dinucleotide which can be effectively photoreduced to the hydroquinone level by: ethylenediaminetetra-acetate > ethylene diaminetetrapropionate > L-methionine > nicotine > dimethylaminopropanol > dimethylglycine ethyl ester > triethylamine. The same compounds can be used to photoreduce flavoproteins, the rates for which are: D-amino acid oxidase > L-amino acid oxidase > glucose oxidase > oxynitrilase > Shethna flavoprotein. The oxidation, reduction stage achieved is characteristic of the protein. Addition of free flavin markedly enhances the photoreduction of those flavoproteins which have a readily dissociable flavin-adenine dinucleotide. Urea enhances the photoreduction rate of flavoproteins in approximate correspondence to their ease of photoreduction in the absence of this reagent. Increase in temperature does not greatly enhance the rate of photoreduction of these flavoproteins. Benzoate decreases the rate of photoreduction of certain of the oxidases. [ABSTRACT FROM AUTHOR]

The absorption of riboflavin (administered as riboflavin-5'-phosphate) was studied in infants and children with thyroid disorders. The kinetics of elimination and the urinary recovery of riboflavin after intramuscular injection of the vitamin did not differ in hypothyroid and hyperthyroid children. On the other hand, oral administration of a large dose of riboflavin resulted in much more than normal absorption in hypothyroid children and in less than normal absorption in hyperthyroid children. Riboflavin absorption became normal in both groups upon successful treatment of the thyroid disorder. The duration of absorption was considerably prolonged in the hypothyroid children and shorter than normal in the hyperthyroid children. This is consistent with the hypothesis that the differences in the extent of absorption are caused by differences in intestinal transit rates due to the thyroid disease. It is likely that changes in intestinal transit rate will also affect the absorption of some drugs. This possibility should be taken into consideration when assessing the response of patients with thyroid disorders to oral medication. [ABSTRACT FROM AUTHOR]

The absorption and excretion of riboflavin, a vitamin which is absorbed in adults by a saturable transport process in the proximal small intestine, was investigated in healthy, 5-day-old infants. After oral administration of a saturation dose of the vitamin (150 mg/sq m), the urinary recoveries of riboflavin in the neonates were similar (about 7% of the dose) to those obtained previously in 3- to 6-month-old infants. However, the maximum excretion rate (per unit of body surface area) of riboflavin was much lower and the duration of maximum excretion rates was much longer in the neonates than in older infants. Data obtained after parenteral administration of riboflavin show that the low maximum excretion rate was not due to limited renal capacity and that the longer duration of excretion was due to prolonged absorption of the vitamin from the intestinal tract. [ABSTRACT FROM AUTHOR]

Deals with the attempt to elucidate the role of riboflavin deficiency in the development of congenital malformations by integrated histological and biochemical studies. Importance of the problems associated with congenital malformations in children to pediatrics.

An assignment of the 13C-NMR spectrum of the enzyme cofactor flavin-adenine dinucleotide (FAD) is given by comparing it with the 13C chemical shifts of the constituents of FAD, i.e. adenosine 5′-diphosphate, riboflavin 5′-monophosphate, riboflavin, adenosine and adenine. The 13C-NMR spectrum of FAD shows three groups of signals: a) At highest field the resonances of the methylgroups (— 18 to — 21 ppm) of the isoalloxazine moiety. b) At lowest field the signals of the carbon atoms of the isoalloxazine ring (—117 to — 161 ppm). c) In the range of —47 to —88 ppm the resonances of the carbon atoms of the ribose and ribitol residue. [ABSTRACT FROM AUTHOR]

Improved methods have been devised for the isolation in μmole quantities of a pure flavin pentapeptide and its acid-hydrolysis product (SD-flavin) from inner-membrane preparations of heart mitochondria and from soluble, purified succinate dehydrogenase. SD-flavin differs from riboflavin in still having an amino acid covalently linked to the isoalloxazine ring system. SD-flavin may be compared with riboflavin and with various 8α-substituted synthetic flavins by optical spectrophotometry in the neutral and cationic states and by ESR and ENDOR spectrometry in the cationic radical state. On the basis of these experiments is was concluded that the FAD prosthetic group of mitochondrial succinate dehydrogenase is covalently linked through the 8α-position to the peptide backbone of the protein. This conclusion is in accord with the acid stability of the natural product and its tendency to yield riboflavin under reductive conditions. The unusual ph-fluorescence spectrum of the flavin strongly suggests that the 8α-methylene group is linked to an amino acid through a tertiary nitrogen group. [ABSTRACT FROM AUTHOR]

Succinate dehydrogenase flavocoenzyme (‘SD-flavin’), previously shown to be an 8α-substituted riboflavin derivative containing a tertiary nitrogen homoconjugated to the flavin nucleus, was subjected to further hydrolysis and to reduction under acid conditions. Both conditions resulted in the liberation of 1 mole of histidine per mole of flavin. This proves histidine to be the covalent link between flavin and peptide backbone in succinate dehydrogenase and imidazole to be the tertiary nitrogen function homoconjugated to the flavin. 8α-Histidyl-riboflavin has been synthesized starting from riboflavin chemically and shown to be completely identical with the natural product in optical, ESR and NMR spectra, pH-fluorescence curve and behavior on thin-layer and paper chromatography, as well as paper electrophoresis. [This equation cannot be represented into ASCII Text] 3. Both the natural compound isolated by acid hydrolysis of flavin peptide and the synthetic one contain two isomers, which may be separated by high voltage electrophoresis. The isomers appear to be the N(1)- and N(3)-imidazole substituted compounds. Digestion of the flavin peptide with aminopeptidase M yields only one isomer but on treatment with 6-N HCl this is gradually converted to a mixture of the two isomers. The absolute assignment of the natural isomer is suggested as 8α-[N(3)-histidyl]-riboflavin on the basis of imidazole quaternization with CH3I, reductive cleavage of the flavin-imidazole bond and identification of the methyl-histidine liberated as 1-methyl-histidine. [ABSTRACT FROM AUTHOR]

In the previous paper in this series it was shown that a pure flavin pentapeptide isolated from hepatic monoamine oxidase contains I mole each of serine and tyrosine and 2 moles of glycine, as well as an additional amino acid which is covalently linked to the 8α carbon of riboflavin. This amino acid has been identified as cysteine and the linkage to the flavin as a thioether on the basis of positive chloroplatinic and negative iodine-azide tests, performic acid oxidation or reduction with zinc, followed by acid hydrolysis, which yield cysteic acid or cysteine, respectively. The fluorescence properties of the flavin from monoamine oxidase agree with those expected for a thioether and its oxidation products. In regard to optical and electron spin resonance spectra, chemical stability, and fluorescence characteristics the flavin peptide isolated from the enzyme agrees excellently with the properties of synthetic cysteinyl 8α-riboflavin. [ABSTRACT FROM AUTHOR]

The inhibition of cell division induced by 2-thiouracil in prothallia of Dryopteris filix-mas and Anemia phyllitidis is reversed by riboflavin as well as by its physiological inactive analogue isoriboflavin. This antagonism is not due to an in vivo interaction as stated by Yeoh and Raghavan, but is rather caused by an in vivo sensibilisation of photo destruction of the inhibitor during early phase of spore germination. Riboflavin as well as isoriboflavin strongly inhibit cell divisions in the prothallia of Anemia phyllitidis. In spite of a significantly reduced growth rate no retardation of the onset of the 2-dimensional differentiation, as related to a critical cell number, can be stated in the Anemia prothallia. [ABSTRACT FROM AUTHOR]

This article focuses on experiments to determine the effect of infiltrated riboflavin-phosphate and the interaction of flavin-mononucleotide fluorescence (FMF) with blue radiation on the hook opening response in bean hypocotyls. The opening response is normally controlled by the phytochrome pigment system and is sensitive to low levels of red radiation. The preliminary conclusion based on blue-induced hook opening responses in the presence of added indoleacetic acid (IAA) or FMN, and both added simultaneously, was that there is no effective inactivation of endogenous auxins by blue light and no observable interaction between added IAA and FMN.

1. The fluorescent pigment produced by Aspergillus repens was isolated by adsorption on Fuller's earth, elution with methanol, and chromatography upon a magnesia column. Its absorption spectrum shows maxima at 270 and at 370—390 mμ. 2. The fluorescence spectrum of this pigment has a maximum at 455 mμ. 3. These findings, together with data derived from infrared studies and paper chromatography indicate that the fluorescent pigment is a pteridine. 4. Culture filtrates of A. repens also contain a non-fluorescent pigment, auroglaucin. [ABSTRACT FROM AUTHOR]

Catalase mediates the decarboxylation and oxidation of indoleacetic acid by acting peroxidatically in a reaction sequence which involves: (a) initiation by manganic ions, (b) peroxide formation, (c) catalysed peroxidation of organic hydrogen donors, (d) manganese oxidation. The peroxidatic activity of catalase is inhibited during the oxidation but the catalatic activity remains unimpared. Light has no effect on the oxidation of indoleacetic acid by catalase systems unless certain inhibitors are present. Undialysed catalase preparations from beef liver contain a photolabite thermostable inhibitor. Ribo-flavinphosphate retards IAA oxidation and light of the blue region over-comes its effect. Light and riboflavinphosphate together do not augment the rate of IAA oxidation beyond that in darkness in the absence of riboflavin. Evidence in favour of the operation of this system in the intact plant is summarized. It is suggested that riboflavin promotes growth by inhibiting indoleacetic acid destruction. Light overcomes the protective effect of riboflavin phosphate in vitro and may thereby inhibit growth. [ABSTRACT FROM AUTHOR]

1. A case is described of pophyria cutanea tarda with recurrent eruption of the exposed skin, particularly in the summer. There is abnormality of porphyrin excretion (about 50 mg. daily in the stool and 2 mg. daily in the urine), but, apart from recent complaints of rather vague abdominal pain, no other abnormality. The patient has a sister with a similar condition and a brother who is normal. The patient's twin daughters are normal. 2. No marked change in porphyrin excretion followed exclusion of green vegetables, or of green vegetables and meat from the diet, or the administration of riboflavin, vitamin B12 or aureomycin. 3. The bile was shown to have a high porphyrin content, thus supporting an endogenous origin for these pigments. 4. The patient's serum contains protoporphyrin. 5. The skin eruption of purpura and oedema was reproduced by sunlight, by sunlight through window glass, and by exposure to an enclosed carbon arc lamp with a very high emission between 3500 and 4100 Å. 6. Histological sections of exposed skin showed gross hyaline swelling of walls of capillaries in the upper corium, and periodic acid-Schiff stain revealed swelling and intense polysaccharide staining of the basement membrane, even when there had been no exposure to sunlight for several weeks. This damage to the minute vase culature may account for the abnormal fragility of the skin. 7. The pattern of porphyrin excretion in porphyria cutanea tarda and the relation of this disease to congenital porphyria and to acute porphyria are discussed in the light of findings in the present case. [ABSTRACT FROM AUTHOR]

The articles presents a study that examines the inhibition of bacterial growth in human saliva by the vitamins B1, B2, and B6. The authors began their study with the knowledge that small amounts of thiamin and pyridoxine can show a partial inhibitory effect to the growth of bacteria in saliva. Experimental methods are detailed.

This article discusses the results of a research study conducted to determine the vitamin requirements of oral bacteria. The researchers investigated the need of certain strains of lactobacilli for some of the B complex factors, including riboflavin, nicotinic acid, and biotin. The study concludes that smaller doses of vitamins support less growth and acid production.

Presents the results of a clinical study which used fluorescent riboflavin and hyaluronidase for visualizing the gallbladder and liver lymphatics. Materials and methods used for the study; Information on the biliary lymph transit time in the rabbit; Alteration of biliary lymph transit time in patients with extensive liver disease.

Radioisotopes of riboflavin, biotin, and folic acid were parenterally administered to marmosets to determine whether the salivary glands contribute to the vitamin content of saliva. Examination after injection showed that there were measurable amounts of each test vitamin in all samples of pilocarpine-stimulated saliva obtained from the test animals. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study designed to determine the effect of an increased intake of Vitamin B2 or riboflavin on the physical growth of a child. The results from the psychological battery tests are inconsistent and cannot be considered valid. The authors conclude that there is a slight gain in physical growth in children under extensive Riboflavin treatment but there is no difference in mental growth.

Chronic cyanide intoxication of dietary origin and riboflavine deficiency are believed to be major aetiological factors in Nigerian tropical ataxic neuropathy. The results are presented of a double-blind controlled therapeutic trial of combinations of large doses of hydroxocobalamin and cystine as cyanide binding agents together with riboflavine or placebos in Nigerian patients suffering from the tropical ataxic neuropathy. No clinical benefit was demonstrable with any of the treatments. [ABSTRACT FROM AUTHOR]

In a small series of cases of hidradenitis suppurativa an inability to utilize glucose normally was observed. The majority showed a flat blood sugar curve. Because of this, we decided to try the effect of riboflavine in small doses given orally : clinically the result was satisfactory. In two cases, one showed a lag curve and responded to riboflavine; the other was diabetic and has only recently come under observation. [ABSTRACT FROM AUTHOR]

The article presents a study regarding the treatment of Rosacea in out-patients at a public hospital in Sydney, Australia with riboflavine, pyridoxine, and vitamin B complex. The results indicate that the treatment was not beneficial, demonstrating clinical improvement that was inconsistent and small. The utility of treatment with hydrochloric acid is also explored.

This article describes a method to ensure that patients of pediatricians are taking their medicine regularly. It was found that family members were unreliable in giving medication to emotionally disturbed children and the children themselves were too ill to be questioned directly. A urine test suggested by Swintosky and mentioned by Scarpetti et al. was employed. These researchers found that urine from patients taking oral riboflavin exhibits a characteristic milky-white fluorescence with yellow at the sides when viewed by ultraviolet light. Thus, 5 mg. tablets of riboflavin were instructed to be taken along with each dose of medicine. This test assumed the presence of no riboflavin in the urine from any other source besides the tablets. Also, an obvious advantage would be gained by combining riboflavin and the medication under study into a single tablet or capsule.

The article presents information about the study "An Appraisal of the Therapeutic Effect of Riboflavin in Psoriasis," by Ashton L. Welsh and Mitchell Ede. In the study, riboflavin administered by the mouth or parenterally, in moderate or in massive dosages, to 348 patients with psoriasis failed to produce any significant response.

The article reports on the influence of riboflavin on fluoride metabolism in rats. Two studies are discussed: one using modified pair-feeding methods in male Wistar rats and another providing the weanling rats with a diet ad libitum. The conclusion is that riboflavin deficiencies are related to fluoride retention.