Home About us Contact
|
Home About us Contact | ||
|
|
||
Vitamin B2 (vitamin + b2)
Selected AbstractsPhysical and Biological Properties of a Novel Hydrogel Composite Based on Oxidized Alginate, Gelatin and Tricalcium Phosphate for Bone Tissue Engineering,ADVANCED ENGINEERING MATERIALS, Issue 12 2007K. Cai A novel hydrogel composite is reported in this study, which was derived from oxidized alginate, gelatin and tricalcium phosphate (TCP). The physical and biological properties of these hydrogel composites prepared with oxidized sodium alginate with different oxidation degrees were investigated. The drug delivery potential of this hydrogel composite as a carrier was evaluated by using Vitamin B2 as a model drug as well. An in vitro investigation with encapsulation of osteoblast revealed that these composites were biocompatible. This hydrogel composite presented here may be utilized for the fabrication of potential injectable systems for tissue engineering, drug delivery and other medical applications. [source] Vitamin B2 -sensitized Photo-oxidation of DopaminePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Walter A. Massad Kinetics and mechanism of the photo-oxidation of the natural catecholamine-type neurotransmitter dopamine (DA) has been studied in aqueous solution, under aerobic conditions, in the presence of riboflavin (Rf, vitamin B2) as a photosensitizer. Results indicate the formation of a weak dark complex Rf,DA, with a mean apparent association constant Kass = 30 m,1, only detectable at DA concentrations much higher than those employed in photochemical experiments. An intricate mechanism of competitive reactions operates upon photoirradiation. DA quenches excited singlet and triplet states of Rf, with rate constants of 4.2 × 109 and 2.2 × 109 m,1 s,1, respectively. With the catecholamine in a concentration similar to that of dissolved molecular oxygen in air-saturated water, DA and oxygen competitively quench the triplet excited state of Rf, generating superoxide radical anion (O2,,) and singlet molecular oxygen (O2(1,g)) by processes initiated by electron and energy-transfer mechanisms, respectively. Rate constants values of 1.9 × 108 and 6.6 × 106 m,1 s,1 have been obtained for the overall and reactive (chemical) interaction of DA with O2(1,g). The presence of superoxide dismutase increases both the observed rates of aerobic DA photo-oxidation and oxygen uptake, due to its known catalytic scavenging of O2,,, a species that could revert the overall photo-oxidation effect, according to the proposed reaction mechanism. As in most of the catecholamine oxidative processes described in the literature, aminochrome is the DA oxidation product upon visible light irradiation in the presence of Rf. It is generated with a quantum yield of 0.05. [source] Alkanethiols Modified Gold Electrodes for Selective Detection of Molecules with Different Polarity and Molecular Size.ELECTROANALYSIS, Issue 3-5 2009Application to Vitamin B2 Analysis Abstract The cyclic voltammetry behavior of several molecules with different polarity and molecular size on gold electrodes modified with nonfunctionalized alkanethiols of different chain length, usually employed as chromatographic stationary phases, are studied. The redox systems hexacyanoferrate(II/III), ferrocene/ferrocine and hydroquinone/quinone are chosen as template molecules. As modifiers, ethanethiol, 1-octanethiol and di- n -octadecyldisulfide are selected. We can conclude that polar molecules can reach the electrode surface through channels created by the modifiers. However, when nonpolar compounds are analyzed, the nonpolar interactions between the analyte and the terminal group of the modifier lead to retention of the compound, retarding its arrival to the electrode surface. A molecule with polar and nonpolar part was used for the application of this conclusion. If the gold electrode is modified with di- n -octadecyldisulfide, the electrochemical behavior of vitamin B2 becomes simpler than that observed on a bare one. This result allows a sensitive and selective procedure to be developed for direct determination of vitamin B2 in pharmaceutical formulations. [source] Effects of high-level dietary B-vitamins on performance, body composition and tissue vitamin contents of growing/finishing pigsJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1-2 2007B. M. Böhmer Summary Forty-eight growing pigs were randomly assigned to five dietary groups and penned individually. They received a diet based on barley, wheat, corn and soya bean meal according to requirement. The experimental groups were supplemented with 400% or 800% of vitamins B2, B6 and pantothenic acid, or 400% or 800% of biotin, while all other vitamins were administered according to requirement. Growth performance, carcass characteristics, aspartate aminotransferase (AST), and content of vitamins in blood, liver and muscles were recorded. Growth performance showed no influence of supplementation, while backfat thickness in the group with 800% B2/B6/pantothenic acid was significantly higher. Content of B2 in blood, liver and muscle was similar in all groups. Content of B6 in blood and liver showed significant differences according to supplementation. The content of vitamin B6 in muscle in the experimental groups was significantly higher than that in the control group. The content of pantothenic acid in blood and muscle in the experimental groups was significantly higher, while in liver all groups were significantly influenced by the supplementation level. Biotin content in liver showed no influence, but the content in plasma was significantly higher in the experimental groups and the content in muscle was significantly higher according to supplementation. The activity of AST showed no significant influence of the dietary vitamin level, but it was obviously decreased in the groups supplemented with biotin. The findings indicate that the dietary supplementation of vitamin B2, B6, pantothenic acid and biotin could not improve performance, but the contents in blood, liver and muscle. [source] Improving the Stability of Probiotic Bacteria in Model Fruit Juices Using Vitamins and AntioxidantsJOURNAL OF FOOD SCIENCE, Issue 5 2010N.P. Shah Abstract:, This study examined the survival of probiotic bacteria in a model fruit juice system. Three different strains of probiotic bacteria were used in this study: HOWARU,Lactobacillus rhamnosus,HN001, HOWARU,Bifidobacterium lactis,HN001, and,Lactobacillus paracasei,LPC 37. The probiotic bacteria were inoculated into model juice with various vitamins and antioxidants, namely white grape seed extract, green tea extract, vitamin B2, vitamin B3, vitamin B6, vitamin C, and vitamin E. The model juice without any additives was used as a control. Their viability was assessed on a weekly basis using plate count method. The model juice was made with sucrose, sodium citrate, citric acid powder, and distilled water and was pasteurized before use. Our findings showed that probiotic bacteria did not survive well in the harsh environment of the model fruit juice. However, the model juice containing vitamin C, grape extract, and green tea extract showed better survival of probiotic bacteria. The model juice containing grape seed extract, green tea extract, and vitamin C had the same initial population of 8.32 log CFU/mL, and at the end of the 6-wk storage period it had an average viability of 4.29 log CFU/mL, 7.41 log CFU/mL, and 6.44 log CFU/mL, respectively. Juices containing all other ingredients tested had viable counts of <10 CFU/mL at the end of the 6-wk storage period. [source] Chemical, biological and sensory evaluation of pasta products supplemented with ,-galactoside-free lupin floursJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2007Alexia Torres Abstract ,-Galactoside-free lupin flour has been used to supplement durum wheat semolina flour in order to increase the nutritive value of pasta products. Supplemented pasta products had a shorter cooking time, higher cooking water absorption, cooking loss and protein loss in water than control pasta prepared with only semolina. Sensory evaluation of cooked pastas showed that products supplemented with 80 g kg,1 of ,-galactoside-free Lupinus angustifolius var. Emir flour or with 100 g kg,1 of ,-galactoside-free Lupinus angustifolius var. Troll flour showed the same acceptability by panellists as the semolina pasta. These levels of supplementation were selected for further studies. The cooked ,-galactoside-free lupin/semolina pastas showed higher amounts of protein, dietary fibre, calcium, phosphorus, magnesium, zinc and antioxidant capacity than control pasta and a reasonable level of vitamin B1, vitamin B2 and vitamin E. Biological assessment of cooked pastas indicated that the true protein digestibility did not change after the fortification of semolina but protein efficiency ratio increased sharply in the pasta supplemented with ,-galactoside-free lupin flours (2.07 and 1.92 for Emir and Troll lupin varieties, respectively) in comparison with the control pasta (1.11). It is concluded that the ,-galactoside-free lupin flours are an adequate ingredient to improve the nutritional quality of pasta products without adding flatulent oligosaccharides. Copyright © 2006 Society of Chemical Industry [source] Effect of package light transmittance on the vitamin content of milk, part 3: Fortified UHT low-fat milkPACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2009Alexander Saffert Abstract This work is the third and last part of a milk study evaluating the effect of package light transmittance on the vitamin content of milk, in this case on fortified UHT low-fat milk. The milk was stored under light with an intensity of 700,lux in polyethylene terephthalate (PET) bottles with varying light transmittance to monitor the changes in the vitamin A, B2 and D3 contents over a storage period of 12 weeks at 23°C. Milk packed in pigmented PET bottles with the lowest light transmittance, which was stored in the dark under the same experimental conditions, served as the ,control' sample. In clear PET bottles, a reduction of 93% of the initial content was observed for vitamin A and 66% for vitamin D3, while the vitamin B2 content was completely degraded. In all pigmented PET bottles, the vitamin retention was only slightly higher; the losses ranged between 70 and 90% for vitamin A, between 63 and 95% for vitamin B2, and between 35 and 65% for vitamin D3 depending on the pigmentation level. In the dark-stored ,control' sample, a 16% loss could be observed for vitamin A, while the level of vitamins B2 and D3 remained almost stable. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of package light transmittance on the vitamin content of pasteurized whole milkPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2006Alexander Saffert Abstract Pasteurized whole milk (3% fat) was stored under fluorescent light at 8°C in clear 1 litre polyethylene terephthalate (PET) bottles and three variants of pigmented PET bottles with different light transmittance. Changes in the vitamin content were monitored over a period of 10 days. Milk packed in pigmented PET bottles with the lowest light transmittance, which was stored in the dark under the same experimental conditions, served as the ,control' sample. Data were obtained for vitamin A (retinol), vitamin B2 (riboflavin) and vitamin B12 (cobalamin) content. Standard plate counts were determined to ensure an acceptable microbiological status of the pasteurized milk during the sampling period. In clear PET bottles a reduction of 22% of the initial content was observed for vitamin A and 33% for vitamin B2, while the vitamin B12 content remained almost stable. In all pigmented PET bottles the vitamin retention was significantly higher; the losses were 0,6% for vitamin A and 11,20% for vitamin B2, depending on the pigmentation level, as compared to 6% for vitamin A and no significant loss for vitamin B2 in the ,control' sample. An impact of the package light transmittance on the vitamin B12 content could not be observed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Vitamin B2 -sensitized Photo-oxidation of DopaminePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Walter A. Massad Kinetics and mechanism of the photo-oxidation of the natural catecholamine-type neurotransmitter dopamine (DA) has been studied in aqueous solution, under aerobic conditions, in the presence of riboflavin (Rf, vitamin B2) as a photosensitizer. Results indicate the formation of a weak dark complex Rf,DA, with a mean apparent association constant Kass = 30 m,1, only detectable at DA concentrations much higher than those employed in photochemical experiments. An intricate mechanism of competitive reactions operates upon photoirradiation. DA quenches excited singlet and triplet states of Rf, with rate constants of 4.2 × 109 and 2.2 × 109 m,1 s,1, respectively. With the catecholamine in a concentration similar to that of dissolved molecular oxygen in air-saturated water, DA and oxygen competitively quench the triplet excited state of Rf, generating superoxide radical anion (O2,,) and singlet molecular oxygen (O2(1,g)) by processes initiated by electron and energy-transfer mechanisms, respectively. Rate constants values of 1.9 × 108 and 6.6 × 106 m,1 s,1 have been obtained for the overall and reactive (chemical) interaction of DA with O2(1,g). The presence of superoxide dismutase increases both the observed rates of aerobic DA photo-oxidation and oxygen uptake, due to its known catalytic scavenging of O2,,, a species that could revert the overall photo-oxidation effect, according to the proposed reaction mechanism. As in most of the catecholamine oxidative processes described in the literature, aminochrome is the DA oxidation product upon visible light irradiation in the presence of Rf. It is generated with a quantum yield of 0.05. [source] Modulation of dynamic release of vitamin B2 from a model pH-sensitive terpolymeric hydrogel systemPOLYMER INTERNATIONAL, Issue 12 2004Dr SK Bajpai Abstract Terpolymeric devices consisting of acrylamide, methacrylamide and acrylic acid were synthesized and the release of the model drug riboflavin from these devices was studied at the physiological temperature 37°C. The gels exhibit a sharp pH-dependent release behavior. The devices released nearly 42.2 ± 2.6% drug at pH 1.0 while nearly 95.3 ± 3.2% drug was released at pH 7.4. With increasing concentration of cross-linker in the gel, the drug released was found to decrease. Moreover, with low content of cross-linker a nearly zero-order profile was obtained. The size of the cylindrical devices also affected the release kinetics and a linear dependency was observed between t1/2 (ie, the time required for 50 % release) and the square of the diameter, thus supporting the Tanaka,Fillmore theory. The molar ratio of acrylamide and methacrylamide also affected the dynamic release of riboflavin. It was found that variation in transit time could also affect the drug-releasing capacity of the devices. Finally, the average and ,late-time' diffusion coefficients for the gels having different initial loads were also evaluated. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||||||||