• Korean Journal of Microbiology
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• v.23 no.3
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• pp.167-171
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• 1985

In order to investigate the origin of the ribityl froup of riboflavin and the involvement of GTP cyclohydrolase II in the riboflavin pathway, we studied the incorporation of $^{14}C-labeled$ guanosine using a well known riboflavin over producer, Ashbya gossypii.Cells were grown in a media containing $(U- ^{14}C)$ guanosine and the riboflavin and GMP were isolated and purifired by column chromatography. The isolated compounds, riboflavin and GMP were labeled in the ribityl and ribosyl side chain and the isoalloxazine and guannine moiety. By comparing the specific radioactivity of each compound we reached a conclusion that the ribose of guanosine is converted directly to the rivityl moiety of riboflavin. The results indicate that biosynthesis of the vitamin begins at the level of a guanosine compound and also suppory the involvement of GTP cyclohydrolase II in one of the early steps in the biosynthetic pathway.

• Journal of Nutrition and Health
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• v.25 no.2
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• pp.150-161
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• 1992

The purpose of this study was to evaluate the riboflavin status of primary school children. Fiftyone subjects were selected as obese group and fiftyfive subjects were selected as control group according to Body Mass Index(BMI) of fifth-graders at a primary school in Taegu. For each subject information on nutrient intake and daily activity pattern were obtained by questionnaire. The riboflavin status was evaluated by urinary riboflavin exvretion The daily energy expenditure per kilogram of body weight was significantly lower in obese group(=47kcal/day) than in control group(=58kcal/day) (p<0.001) However the entire energy consumption was siginificantly greater in the obese children(=2005kcal/day) than their nono-baser peers(=1837kcal/day)(p<0.001). Riboflavin intake was 0.67mg/100kcal in the control group and 0.61mg/1000kcal in the obese group. Thus intakes for both groups met the current group and control group were 86.9$\mu\textrm{g}$/day and 98.7$\mu\textrm{g}$/day. repectively. There was no significnat Assesment of clinical signs of riboflavin deficiency indicated that angular lesion was 4.7% and glossitis was 6.6% of all subjects. Thirty one percent of subjects excrete riboflavin below 78$\mu\textrm{g}$/g creatinine which is defined as deficient. Therefore this group would be considered at high risk for developing riboflavin deficiency. From this study current recommendation of 0.6mg/1000kcal of riboflavin intake may not be adequate during growth and associated stress.

• Journal of Nutrition and Health
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• v.9 no.2
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• pp.54-58
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• 1976

Inadequacy of riboflavin intake among Koreans had been pointed out repeatedly in most dietary and nutritional surveys in Korea. The consumption rate of dairy products has been increasing markedly in recent years. Milk and milk products are known to be a good source of the vitamin which can easily be destroyed by the sunlight. Total riboflavin content of the pasteurized and homogenized milk, both plain and flavored, and the milk products were measured by the Lumiflavin method. It ranged from $62.4{\mu}g$ riboflavin per 100g of homogenized milk to $195.9{\mu}g$ for vanilla flavored ice cream. In general milk products in the form of cream contained about three times as much riboflavin as plain milk. The rates of destruction of riboflavin in chocolate milk and white milk in clear glass bottle and in polyethylene pack were different when measured in 30 min intervals after exposure to bright sunlight for two hours. In the case of the plain milk, the riboflavin content decreased rapidly and remained only about a quarter of the initial value within an hour of the exposure period. The destruction rate slowed down after the first hour of the exposure and resulted about 90% destruction of riboflavin in two hours. The chocolate milk however exhibited a protective effects of the riboflavin from the sunlight. It retained 65% of the initial riboflavin after an hour of the exposure to sun and 55% ofter two hours. Two most widely used milk containers, clear glass bottle and polyethylene pack were about equally affected by the sunlight.

• Korean Journal of Microbiology
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• v.38 no.3
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• pp.173-179
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• 2002

The functions of riboflavin synthesis genes ( ribI,II,III and IV) found immediately downstream of luxG in the lux operon from Photobacterium species were identified using the biochemical and genetical analysis. The ribI-III gene codes for protein corresponding to that coded by the second (riboflavin synthase), third (3,4-dihydroxy 2-butanone 4-phosphate synthase/GTP cyclohydrolase II) and fourth (lumazine synthase) gene, respectively, of Bacillus subtilis rib operon with the respective gene procuct sharing 41-50% amino acid sequence identity. Unexpectedly, the sequence of the ribIV product of Photobacterium phosphoreum does not correspond in sequence to the protein encoded by the fifth rib gene of Bacillus subtilis. Instead the gene (ribIV) codes for a polypeptide similar in sequence to GTP cyclohydrolase II of Escherichia coli and the carboxy terminal domain of the third rib gene from Bacillus subtilis. Complementation of Escherichia coli riboflavin auxotrophs showed that the function of the gene products of ribII and ribIV are DHBP synthase and GTP cyclohydrolase II, respectively. In addition the experiment, showing that increase in thermal stability of riboflavin synthase coded by ribIon coexpression with ribIII, provided indirect evidence that the latter gene codes for lumazine synthase.

• Biomedical Science Letters
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• v.26 no.4
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• pp.288-295
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• 2020

Infection of Helicobacter pylori on gastric mucosa is associated with various gastric diseases. According to the WHO, H. pylori causes gastric cancer and has been classified as a class I carcinogen. Riboflavin is an essential vitamin which presents in a wide variety of foods. Previous studies have shown that riboflavin/UVA was effective against the growth inhibition of Staphylococcus aureus, S. epidermidis and multidrug-resistant Pseudomonas aeruginosa and had the potential for antimicrobial properties. Thus, we hypothesized that riboflavin has a potential role in the growth inhibition of H. pylori. To demonstrate inhibitory concentration of riboflavin against H. pylori, we performed agar and broth dilution methods. As a result, we found that riboflavin inhibited the growth of H. pylori. The MIC was 1 mM in agar and broth dilution test. Furthermore, to explain the inhibitory mechanism, we investigated whether riboflavin has an influence on the replication-associated molecules of the bacteria using RT-PCR to detect mRNA expression level in H. pylori. Riboflavin treatment of H. pylori led to down-regulation of polA and dnaB mRNA expression levels in a dose dependent manner. After then, we also confirmed whether riboflavin has cytotoxicity to human cells. We used AGS, a gastric cancer cell line, and treated with riboflavin did not show statistically significant decrease of cell viability. Thus, these results indicate that riboflavin can suppress the replication machinery of H. pylori. Taken together, these findings demonstrate that riboflavin inhibits growth of H. pylori by inhibiting replication of the bacteria.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.339-347
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• 2006

Riboflavin caused induction of systemic resistance in chickpea against Fusarium wilt and charcoal rot diseases. The dose effect of 0.01 to 20 mM riboflavin showed that 1.0 mM concentration was sufficient for maximum induction of resistance; higher concentration did not increase the effect. At this concentration, riboflavin neither caused cell death of the host plant nor directly affected the pathogen's growth. In time course observation, it was observed that riboflavin treated chickpea plants were inducing resistance 2 days after treatment and reached its maximum level from 5 to 7 days and then decreased. Riboflavin had no effect on salicylic acid(SA) levels in chickpea, however, riboflavin induced plants found accumulation of phenols and a greater activities of phenylalanine ammonia lyase(PAL) and pathogenesis related(PR) protein, peroxidase was observed in induced plant than the control. Riboflavin pre-treated plants challenged with the pathogens exhibited maximum activity of the peroxidases 4 days after treatment. Molecular weight of the purified peroxidase was 42 kDa. From these studies we demonstrated that riboflavin induced resistance is PR-protein mediated but is independent of salicylic acid.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.75-88
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• 2001

In this paper, the microbial production of riboflavin is reviewed and includes descriptions of riboflavin overproducers, and the biosynthesis and details of the key-enzyme genes related to riboflavin. There kinds of riboflavin overproducers are known; Bacillus subtilis and Candida famate utilize glucose as a carbon source, but the fungus Ashbya gossypii requires plant oil as its sole carbon source. The starting material in ribofalvin biosynthesis is guanosine triphospate (GTP), which is converted to riboflavin through six enzymatic reactions. Though Bacillus subtilis, Candida famate, and Ashbya gossypii operate via different pathways until GTP, they follow the same pathway from GTP to riboflavin. From the metabolic viewpoint, with respect to improved riboflavin production, the supplementation of GTP, aprocess-limiting precursor must be considered. The GTP fluxes originate from three sources, serine, threonine and glyoxylate cycles. The development of pathways to strengthen GTP supplementation using biotechnological techniques remains an issue fro future research.

• YAKHAK HOEJI
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• v.28 no.2
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• pp.101-127
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• 1984

The study of interaction between riboflavin derivatives and biologically active substances was reviewed. With combination of spectroscopic methods such as NMR, UV, Fluorescence and IR, informations about interaction mechanism including hydrogen bond formation, conformation of association complex, and association constant were obtained. 1. Riboflavin associated with adenine but not with other bases found in the nucleic acids. -CONHCO- group was included in the formation of hydrogen bond with adenine. 2. Riboflavin interacted with alcohol to make a 1 : 1 association complex through the 3N-imino and 2C-carbonyl group of the isoalloxazine ring and the hydroxyl group of the alcohols. 3. Riboflavin associated with salicylates to produce the cyclic hydrogen-bonded dimer. The strongest complex was formed with salicylic acid, a weaker one with aspirin, and an even weaker one with salicylamide. 4. Other bio-active substances, orotic acid and inhibitors such as phenol, trichloroacetic acid and indol also formed hydrogen bond with riboflavin. 5. Reduced riboflavin showed strong self-association to produce the cyclic hydrogen-bonded complex and it associated with adenine and with cytosine to form 1 : 3 complex.

• Journal of Nutrition and Health
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• v.26 no.6
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• pp.680-691
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• 1993

Rats were fed for an 8-week period a low riboflavin diet(5ug riboflavin/day) or a control diet(30ug/day) supplied either ad libitum or by pair feeding in order to study the effect of riboflavin on the metabolism of lipids and neurotransmitters. Erythrocyte glutathione reductase (EGR) and monomine oxidase(MAO) activity in the liver and brain were assayed. EGR activity coefficient in riboflavin deficient rats was significantly higher than in ad libitum controls whereas MAO activity was decreased in the deficient rats. Fatty acid composition showed a different trend in the serum, liver and brain. In the serum, the concentrations of essential fatty acids and $\omega$-3 fatty acids(eicosapentaenoic acid, docosahexaenoic acid)were decreased about 20-40% in the deficient and pair-fed than in the ad libitum controls. Brain serotonin and 5-HIAA(5-hydroxyindole acetic acid) concentrations were decreased in the riboflavin deficient rats. Learning ability measured by a water maze and exploratory activity using the open field test were not impaired in the deficient rats. These results indicate that brain lipid metabolism was protected in subclinical riboflavin deficiency, however, riboflavin deficiency affected brain serotonin content.

• Korean journal of food and cookery science
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• v.18 no.4
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• pp.461-469
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• 2002

In order to develop a better food preparation method in terms of vitamin retention in food service establishments, the retention rate of riboflavin in two kinds of Korean dish (stir-fried sausage with vegetables, stir-fried garlic young stems) were examined during various cooking stages, holding temperature and duration time. Riboflavin content of the sample was analyzed using by using a HPLC with a fluorescent detector at various holding durations and temperatures. Also the changes in the pH and water contents of the samples were measured during holding at various temperatures to find any relation among the pH, water contents and riboflavin content. In the results, there were significant differences in riboflavin contents at various cooking processes such as washing, slicing, blanching, soaking, etc. Also, the retention rates of riboflavin at various holding methods and temperature were significantly different from one another. Especially 50% reduction of riboflavin content occurred during blanching of young garlic stem and only 38% of riboflavin was left after slicing carrots for stir-frying of sausage.