- Comparison of the Optoelectronic Performance of Neutral and Cationic Forms of Riboflavin
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The riboflavin dye 2,3,4,5-tetra-O-acetyl-1-[3-(6-bromohexyl)-7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl]-1-deoxypentitol and its pyridinium salt were synthesized, and studied by absorption and fluorescence spectroscopy in solutions and
- Saltan, G?zde Murat,K?ymaz, Deniz Aykut,Zafer, Ceylan,Din?alp, Haluk
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- Synthesis and biological activities of novel dexibuprofen tetraacetylriboflavin conjugates
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A series of novel dexibuprofen derivatives covalently linked via alkylene spacers of variable length to tetraacetylated riboflavin have been developed. The target compounds became accessible by reaction of the chloromethyl ester of dexibuprofen with tetraacetylriboflavin (compound 7) or by synthesis of the appropriate N3-(ω-iodoalkyl)-2′,3′,4′,5′-Tetraacetylri boflavin followed by treatment with dexibuprofen (derivatives 8-11), respectively. Biological screening revealed that the target compounds exhibit antiproliferative effects on MCF-7 breast cancer and HT-29 colon carcinoma cells with IC50 values in the range of 8-15 μM. Enzymatic studies on human platelets indicated significant COX-1 inhibitory activities of the target compounds.
- Banekovich, Christian,Ott, Ingo,Koch, Thao,Matuszczak, Barbara,Gust, Ronald
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- Formation of a Transient Radial Ion Pair in the Reactions of 1,5-Dihydroflavin with Hydride Acceptors
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The formation of a transient radical ion pair has been detected directly in the reactions of 1,5-dihydroriboflavin-2',3',4',5'-tetraacetate (FIH2) with hydride acceptors (tetracyano-p-quinodimethane, tetracyanoethylene and p-benzoquinone derivatives) in deaerated acetonitrile, providing unequivocal evidence for an electron transfer pathway in the overall two-electron redox reactions of FIH2 with hydride acceptors.
- Ishikawa, Masashi,Yamamoto, Kazuhiko,Fukuzumi, Shunichi
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- Efficient catalysis of rare-earth metal ions in photoinduced electron-transfer oxidation of benzyl alcohols by a flavin analogue
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A flavin analogue (riboflavin-2′,3′,4′,5′-tetraacetate, Fl) forms the 1:1 and 1:2 complexes with rare-earth metal ions. The largest formation constants K1 and K2 for the 1:1 and 1:2 complexes between Fl and Sc3+ are determined as K1 = 3.1 × 104 M-1 and K2 = 1.4 × 103 M-1, respectively. The complexation of Fl with rare-earth metal ions results in blue shifts of the fluorescence maximum, shortening of the fluorescence lifetime, and more importantly the change in the lowest excited state from the n,π* triplet state of Fl to the π,π* singlet states of Fl-rare-earth metal ion complexes as indicated by the disappearance of the triplet-triplet (T-T) absorption spectrum of Fl by the complexation with metal ions. The strong complex formation between Fl and rare-earth metal ions enhances the oxidizing ability of the excited state of Fl as indicated by the significant acceleration in the fluorescence quenching rates of Fl-rare earth metal ion complexes via electron transfer from electron donors (e.g., alkylbenzenes) as compared to those of uncomplexed Fl. The one-electron reduction potential of the singlet excited state of the 1:2 complex between Fl and Sc3+, 1(Fl-2Sc3+)* (* denotes the excited state), is positively shifted by 780 mV as compared to 1Fl*. Such a remarkable enhancement of the redox reactivity of 1(Fl-2Sc3+)* as compared to that of 1Fl* makes it possible to oxidize efficiently p-chlorobenzyl alcohol to p-chlorobenzaldehyde by 1(Fl-2Sc3+)*, although no photooxidation of p-chlorobenzyl alcohol by Fl occurred in deaerated MeCN. The quantum yield for the photooxidation of p-chlorobenzyl alcohol by Fl-2Sc3+ is the largest among various Fl-metal ion complexes. A comparison of the observed rate constant derived from the dependence of the quantum yield on the concentration of p-chlorobenzyl alcohol with the fluorescence quenching rate constant by electron transfer from the alcohol and the direct detection of radical intermediates reveal that the photooxidation proceeds via electron transfer from p-chlorobenzyl alcohol to 1(Fl-2Sc3+)*. Under an atmospheric pressure of oxygen, the photooxidation of p-methoxybenzyl alcohol by oxygen proceeds efficiently in the presence of Fl-Lu3+ which acts as an efficient photocatalyst. No photodegradation was observed in the case of the Fl-Lu3+ complex, whereas the facile photodegradation of Fl-Mg2+ has precluded the efficient photocatalytic oxidation of the alcohol by oxygen.
- Fukuzumi, Shunichi,Yasui, Kiyomi,Suenobu, Tomoyoshi,Ohkubo, Kei,Fujitsuka, Mamoru,Ito, Osamu
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- (Trifluoromethylselenyl)methylchalcogenyl as Emerging Fluorinated Groups: Synthesis under Photoredox Catalysis and Determination of the Lipophilicity
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The synthesis of molecules bearing (trifluoromethylselenyl)methylchalcogenyl groups is described via an efficient two-step strategy based on a metal-free photoredox catalyzed decarboxylative trifluoromethylselenolation with good yields up to 88 %, which raised to 98 % in flow chemistry conditions. The flow methods allowed also to scale up the reaction. The mechanism of this key reaction was studied. The physicochemical characterization of these emerging groups was performed by determining their Hansch–Leo lipophilicity parameters with high values up to 2.24. This reaction was also extended to perfluoroalkylselenolation with yields up to 95 %. Finally, this method was successfully applied to the functionalization of relevant bioactive molecules such as tocopherol or estrone derivatives.
- Grollier, Kevin,De Zordo-Banliat, Arnaud,Bourdreux, Flavien,Pegot, Bruce,Dagousset, Guillaume,Magnier, Emmanuel,Billard, Thierry
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supporting information
p. 6028 - 6033
(2021/03/15)
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- Synthesis and evaluation of antimycobacterial activity of riboflavin derivatives
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The riboflavin biosynthetic pathway is a promising target for the development of novel antimycobacterial drugs given the lack of riboflavin transporter in M. tuberculosis. Herein, a series of riboflavin derivatives was designed, synthesized and screened for their antimycobacterial and antibacterial activity. The compounds 1a, 1b, 2a, 3a and 5a displayed noticeable antitubercular activity against M. tuberculosis with minimum inhibitory concentration (MIC99) in the range of 6.25 to 25 μM. The lead compound 5a had a selectivity index of 10.7 in the present study. The compounds 2a, 2b, 2c, 4c and 4d showed relatively low to moderate antibacterial activity (MIC = 100–200 μM) against gram-positive strains. Notably, the compounds do not show any inhibition against gram-negative strains even at 200 μM concentration. Further, molecular docking and binding experiments with representative flavin mononucleotide (FMN) riboswitch suggested that the riboflavin analogs exhibited antimycobacterial activity plausibly through FMN riboswitch-mediated repression of riboflavin biosynthesis. In addition to FMN riboswitch, flavoproteins involved in the flavin biosynthesis could also be target of riboflavin derivatives. In conclusion, the potency and low toxicity of riboflavin analogs particularly 5a (MIC99 = 6.25) make it a lead compound for the synthesis of new analogs for antimycobacterial therapy.
- Chouhan, Dwarika Kumar,Harale, Bhaiyyasaheb,Khedkar, Vijay,Kidwai, Saqib,Ojha, Divya,Rode, Ambadas B.,Singh, Manisha,Singh, Ramandeep
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supporting information
(2021/07/16)
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- Visible-light promoted allylation of N-substituted tetrahydroisoquinoline using riboflavin tetra-acetate as photocatalyst
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Riboflavin (RF) and relative derivatives are important coenzyme of some redox enzymes controlling the growing development of plants by harvesting light. The unique isoalloxazine structure unit with special photoredox capacity makes it applicable to induce
- Cheng, Pi,Dong, Zhuang,Fan, Shulin,Huang, Pilin,Song, Yunfei,Wang, Lin,Wang, Xinhao,Zeng, Jianguo
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supporting information
(2021/08/04)
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- Electrochemistry Broadens the Scope of Flavin Photocatalysis: Photoelectrocatalytic Oxidation of Unactivated Alcohols
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Riboflavin-derived photocatalysts have been extensively studied in the context of alcohol oxidation. However, to date, the scope of this catalytic methodology has been limited to benzyl alcohols. In this work, mechanistic understanding of flavin-catalyzed oxidation reactions, in either the absence or presence of thiourea as a cocatalyst, was obtained. The mechanistic insights enabled development of an electrochemically driven photochemical oxidation of primary and secondary aliphatic alcohols using a pair of flavin and dialkylthiourea catalysts. Electrochemistry makes it possible to avoid using O2 and an oxidant and generating H2O2 as a byproduct, both of which oxidatively degrade thiourea under the reaction conditions. This modification unlocks a new mechanistic pathway in which the oxidation of unactivated alcohols is achieved by thiyl radical mediated hydrogen-atom abstraction.
- Zhang, Wen,Carpenter, Keith L.,Lin, Song
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supporting information
p. 409 - 417
(2019/11/25)
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- Riboflavin as Photoredox Catalyst in the Cyclization of Thiobenzanilides: Synthesis of 2-Substituted Benzothiazoles
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Benzothiazoles are synthesized from thiobenzanilides using riboflavin as a photosensitizer and potassium peroxydisulfate as a sacrificial oxidizing agent under visible light irradiation. The methodology accepts a broad range of functional groups and affords the 2-substituted benzothiazoles by transition-metal-free organic photoredox catalysis under very mild conditions.
- Bouchet, Lydia M.,Heredia, Adrián A.,Argüello, Juan E.,Schmidt, Luciana C.
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supporting information
p. 610 - 614
(2020/01/31)
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- Selenium-containing compound and use thereof
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The invention relates to an application of riboflavin selenium derivative shown in the description in preparing cancer chemopreventive agent. The compound is capable of significantly inducing the expression of quinone reductase and without significant cytotoxic effect under enzyme-induced activity concentration conditions, and can be used as effective cancer chemopreventive and therapeutic agent.
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Paragraph 0033
(2019/01/23)
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- Covalent Immobilization of (?)-Riboflavin on Polymer Functionalized Silica Particles: Application in the Photocatalytic E→Z Isomerization of Polarized Alkenes
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The covalent immobilization of the biomimetic, photo-organocatalyst (?)-riboflavin on silica micro- and nanoparticles via atom transfer radical polymerization (ATRP) is disclosed. Given the effectiveness of (?)-riboflavin as a versatile, environmentally benign photocatalyst, an immobilization strategy based on acrylate-linker modification of the catalyst core and controlled polymerization on initiator pre-functionalized silica particles has been developed. Validation of this approach is demonstrated in the E→Z isomerization of a benchmark cinnamonitrile (Z/E up to 88:12) with 0.97 mol % catalyst loading. Characterization of the immobilized photocatalyst supports covalent embedding of the catalyst in the polymeric brushes on the silica particle surface.
- Metternich, Jan B.,Sagebiel, Sven,Lückener, Anne,Lamping, Sebastian,Ravoo, Bart Jan,Gilmour, Ryan
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supporting information
p. 4228 - 4233
(2018/03/21)
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- Visible light mediated aerobic photocatalytic activation of C–H bond by riboflavin tetraacetate and N-hydroxysuccinimide
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A green and highly efficient cooperative photocatalytic system which consists of riboflavin tetraacetate (RFT), N-hydroxysuccinimide (NHS) and FeCl3·6H2O has been developed for C–H bond oxygenation with visible light under mild reaction conditions. Compared to the previous procedures about C–H bond activation by using flavins as photocatalyst, we use cheap ferric chloride and NHS instead of expensive scandium triflate or biomimetic non-heme iron complex, further expand the substrate scopes. In addition, a possible radical mechanism for the C–H bond oxygenation in this photocatalytic system is proposed.
- Tang, Guo,Gong, Zhiyu,Han, Wenjun,Sun, Xiaoling
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supporting information
p. 658 - 662
(2018/01/18)
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- Development of a Flow Photochemical Aerobic Oxidation of Benzylic C-H Bonds
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A continuous mesofluidic process has been developed for benzylic C-H oxidation with moderate to good yields using a photocatalyst (riboflavin tetraacetate, RFT) activated by a UV lamp and an iron additive [Fe(ClO4)2] via incorporation of singlet oxygen (1O2) for the direct formation of oxidized C=O or CH-OH compounds.
- Lesieur, Mathieu,Genicot, Christophe,Pasau, Patrick
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supporting information
p. 1987 - 1990
(2018/04/16)
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- Containing selenium compound and use thereof (by machine translation)
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The invention relates to a formula I compound including selenium shown in preparing cancer chemopreventive agent and in the application of the therapeutic agent. The experiment confirmed that the formula (I) compounds can remarkably induction quinone reductase expression, and in has the quinone reductase inducing activity under the conditions of the concentration (20 μm) without obvious a cytotoxic effect, can be used as effective cancer chemopreventive agent or therapeutic agent. (by machine translation)
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Paragraph 0030; 0031
(2017/05/23)
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- A Remarkable Oxidative Cascade That Replaces the Riboflavin C8 Methyl with an Amino Group during Roseoflavin Biosynthesis
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Roseoflavin is a naturally occurring riboflavin analogue with antibiotic properties. It is biosynthesized from riboflavin in a reaction involving replacement of the C8 methyl with a dimethylamino group. Herein we report the identification of a flavin-dependent enzyme that converts flavin mononucleotide (FMN) and glutamate to 8-amino-FMN via the intermediacy of 8-formyl-FMN. A mechanistic proposal for this remarkable transformation is proposed.
- Jhulki, Isita,Chanani, Prem K.,Abdelwahed, Sameh H.,Begley, Tadhg P.
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supporting information
p. 8324 - 8327
(2016/07/26)
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- Efficient Metal-Free Aerobic Photooxidation of Sulfides to Sulfoxides Mediated by a Vitamin B2Derivative and Visible Light
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We have developed a metal-free process for the aerobic photooxygenation of sulfides to sulfoxides mediated by riboflavin tetraacetate or riboflavin (vitamin B2) photocatalysts and visible light (450 nm) in an acetonitrile-water (85:15 v/v) mixture. The optimised solvent system leads to both singlet-oxygen and electron-transfer pathways in photooxygenation, thus allowing oxidation of electron-poor and electron-rich thioanisoles, dialkyl sulfides and sterically hindered sulfides. Besides having a broad substrate scope, the method has very short reaction times and requires low catalyst loading (down to 0.1 mol%). These properties are due to the high photocatalyst stability and the extremely high quantum yields (1.3 for thioanisole oxygenation). Moreover, the method is chemoselective, producing only sulfoxides without overoxidation to sulfones. Taking into account the broad substrate scope, high selectivity and high efficiency, this method distinguishes itself from those previously reported. Other advantages include easy work-up of the reaction mixture, the availability and biodegradability of the photocatalysts and mild reaction conditions. We demonstrated, on a preparative scale, its practical application in the synthesis of the psychostimulant modafinil, in the selective oxidation of methionine derivatives, and in the detoxification of mustard gas. (Figure presented.).
- Nevesely, Tomá?,Svobodová, Eva,Chudoba, Josef,Sikorski, Marek,Cibulka, Radek
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supporting information
p. 1654 - 1663
(2016/10/13)
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- Riboflavin derivatives for enhanced photodynamic activity against Leishmania parasites
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Riboflavin derivatives with various substituents (O-acyl, N-methyl, N-alkylcarboxyalkyl or N-alkyl(trialkyl)ammonium) have been prepared and spectroscopically characterized (absorption, emission and fluorescence quantum yields). Their quantum yields of photosensitized singlet molecular oxygen production (ΦΔ 0.24-0.58) and octanol/water partition coefficients (Pow ≤0.01-11) were measured. Preliminary studies indicate that all derivatives display higher phototoxicity against the human protozoan parasite Leishmania than the parent riboflavin, with negligible toxicity in the absence of light. Their photodynamic action shows a higher correlation with P;bsubesub& than with Φbsubesub&, opening up their potential application to cutaneous diseases treatment.
- Silva, Alexandre Vieira,López-Sánchez, Almudena,Junqueira, Helena Couto,Rivas, Luis,Baptista, Mauricio S.,Orellana, Guillermo
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p. 457 - 462
(2015/02/02)
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- A low-molecular-weight supramolecular hydrogel of riboflavin bolaamphiphile for VEGF-siRNA delivery
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A low-molecular-weight hydrogel derived from riboflavin (vitamin B 2) that self-assembles to provide supramolecular nanofibers, biocompatible material, can be used to deliver VEGF-siRNA efficiently into human cells by the endocytosis pathway, where the siRNA is functionalized.
- Patil, Sachin Prakash,Jeong, Hyun Seok,Kim, Byeang Hyean
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supporting information
p. 8901 - 8903
(2012/11/14)
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- Redox reaction between m-thiocresol and riboflavin glycosides with 2:1 complex formation; regulation by the steric effect of sugar in the side chain
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We investigated the reduction of riboflavin-2′, 3′, 4′, 5′-tetra-acetate (AcB2), riboflavin-1″-glucoside- 2″, 3″, 4″, 6″, 2′, 3′, 4′, 5′-hepta-acetate (AcB2gl) and lumiflavin using m-thiocresol (mTc) in the presence of tetrabutylammonium hydroxide. The series of rate constants for AcB2 and AcB2gl reductions indicated that modified Lineweaver-Burk plots were best fit by assuming a 1:2 complex formation. The complex formation in the reaction was supported by the 2-D nuclear Overhauser enhancement spectroscopy and circular dichroism spectra. The modified Michaelis-Menten constants (Km) for AcB2 and AcB2gl with mTc were 1.32 and 0.86 × 10-3M 2, respectively, and the maximum rate constant k2 were 4.45 and 4.35 × 10-2M-1s-1, respectively. The E1/2 values of AcB2 and AcB2gl were - 331 and - 341mV, respectively, which indicated that their reduction activities were almost the same. It was established that the redox function depended on the formation of the complex and was regulated by the steric effect of the sugar in the side chain.
- Takahashi, Keiko,Odajima, Hiroshi,Nuiya, Saori,Hasebe, Yasushi
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scheme or table
p. 252 - 255
(2012/05/19)
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- Synthesis of dimeric quinazolin-2-one, 1,4-benzodiazepin-2-one, and isoalloxazine compounds as inhibitors of amyloid peptides association
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The synthesis of dimeric compounds derived from quinazolin-2-one and 1,4-benzodiazepin-2-one possessing a piperazine or homopiperazine spacer was investigated. In addition, a piperazine spacered bis-isoalloxazine and a bis-riboflavin compound were prepared and their ability to interrupt the association of prion proteins and Alzheimer-specific Aβ peptides was investigated using a fast screening system based on flow cytometry. The bis-isoalloxazine 14 was identified as a new lead structure.
- Barthel, Alexander,Trieschmann, Lothar,Stroehl, Dieter,Kluge, Ralph,Boehm, Gerald,Csuk, Rene
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experimental part
p. 445 - 452
(2009/12/05)
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- Biosensor-Based Determination of Riboflavin in Milk Samples
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An assay for quantification of riboflavin (Rf) in milk-based products has been developed using the principle of surface plasmon resonance with on-chip measurement. The quantification was done indirectly by measuring excess of Rf binding protein (RBP) that remains free after complexation with Rf molecules originally present in the sample solution. The chip was modified with covalently immobilized Rf in order to bind the RBP in excess. A chemical modification was performed to introduce a reactive ester group at the N-3 position of the natural Rf to bind amino groups present on the chip surface. Calibration solutions were prepared by mixing a range of Rf standard solutions with an optimized concentration of RBP. The Rf content in the milk-based products was then measured by comparison of the response against the calibration. Results obtained were very close to those from an official HPLC-fluorescence procedure. The limit of quantification was determined to 234 μg/L and the limit of detection to 70 μg/L by an injection volume of 160 μmL.
- Caelen, Isabelle,Kalman, Andras,Wahlstroem, Lennart
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p. 137 - 143
(2007/10/03)
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- Photochemistry of Flavins in Micelles: Specific Effects of Anionic Surfactants on the Monomerization of Thymine Cyclobutane Dimers Photosensitized by Tetra-O-acyl Riboflavins
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It was found that tetra-o-acyl riboflavins efficiently photosensitize the monomerization of the cis, syn-cyclobutane dimers of 1,3-dimethylthymine and 1,3-dimethyluracil in aqueous solution in the presence of such anionic surfactants as sodium dodecyl sulfate and sodium hexadecyl sulfate at concentrations higher than their critical micelle concentration, while little monomerization of the dimers was photosensitized by the flavins in the absence of the surfactants and even in the presence of cationic and nonionic surfactants.
- Yasuda, Masahide,Nishinaka, Yoshimasa,Nakazono, Takumi,Hamasaki, Takeshi,Nakamura, Nobuya,Shiragami, Tsutomu,Pac, Chyongjin,Shima, Kensuke
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p. 192 - 197
(2007/10/03)
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- Dynamically modified, biospecific optical fiber sensor for riboflavin binding protein based on hydrophobically associated 3-octylriboflavin
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A new approach to the production of optical fiber sensors Is described which Is based on a dynamic modification procedure. In this approach, the optical fiber surface is rendered Hydrophobic through the covalent attachment of a C18 moiety. Specific sensing ligands are then associated with this surface through either their inherent or designed hydrophobicity. To investigate the feasibility of the approach, an optical fiber sensor has been constructed for riboflavin binding protein in which 3-octylriboflavin is associated with the fiber surface. Fluorescence quenching occurs upon binding of the protein to the immobilized riboflavin derivative. The sensor possesses a minimum measurable quantity of 7.3 pmol of binding protein in a probe volume which is less than 10 μL. With this approach, the sensing surface was repetitively regenerated 15 times over a 1-h period with less than a 5% variation in sensor-to-sensor performance. The approach is general, and with minor variations it can be used in a variety of sensing situations.
- Ogasawara, Faye K.,Wang, Yunlong,Bobbitt, Donald R.
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p. 1637 - 1642
(2007/10/02)
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