Spectroscopy and photophysics of flavin related compounds: Riboflavin and iso-(6,7)-riboflavin

Sikorska, Ewa; Khmelinskii, Igor; Komasa, Anna; Koput, Jacek; Ferreira, L. F. Vieira; Herance, José Raúl; Bourdelande, J. L.; Williams, Siân L.; Worrall, David R.; Insińska-Rak, Małgorzata; Sikorski, Marek

doi:10.1016/j.chemphys.2005.03.005

Cited by 74 publications

(65 citation statements)

References 46 publications

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“…(-)-Riboflavin is a naturally occurring yellow pigment found in various plants and microorganisms [9,10]. (-)-Riboflavin has been used widely in biomedical area because of its water-solubility and biocompatibility [11][12][13][14][15][16][17][18][19]. It has been reported that the overdose of (-)-riboflavin does not lead to any side effects because the excess is excreted in the urine within a few hours of ingestion of the vitamin [9].…”

Section: Introductionmentioning

confidence: 99%

Visible light induced dextran-methacrylate hydrogel formation using (−)-riboflavin vitamin B2 as a photoinitiator and L-arginine as a co-initiator

Kim

Chu

2009

Fibers Polym

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The objective of this study is to examine the feasibility of using visible light to form gels from polysaccharide precursors. Hydrogel formation by visible light irradiation would be very beneficial because visible light is a benign light source and ready available when compared with other light sources such as UV. Dextran-methacylate was synthesized and photocrosslinked using (-)-riboflavin as a photoinitiator and L-arginine as a co-initiator under the visible light. The effect of various concentrations of (-)-riboflavin and L-arginine on the photocrosslinking of dextran-methacrylate hydrogel was investigated. The fabricated hydrogel was characterized by FT-IR and SEM. The photoinitiator [(-)-riboflavin] and co-initiator (L-arginine) as well as dextran precursor are completely biocompatible. The optimum condition for the biocompatible dextran-based hydrogel formation under the harmless light source (visible light) was elucidated in this study. In general, the (-)-riboflavin, 0.01-0.5 %, and L-arginine, 5-20 % of the weight of dextran-methacrylate were the best condition in forming dextran-based hydrogels under the visible light. The three-dimensional hydrogel structure was verified by SEM morphology of swollen hydrogels. Photocrosslinking under the visible light source would enlarge the applications of this type of photocrosslinking in the biomedical area (e.g., eyes or other light-sensitive organs).

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Section: Introductionmentioning

confidence: 99%

Visible light induced dextran-methacrylate hydrogel formation using (−)-riboflavin vitamin B2 as a photoinitiator and L-arginine as a co-initiator

Kim

Chu

2009

Fibers Polym

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“…The experimental studies have been assisted by various ab initio calculations. [34][35][36][37][38][39][40] In many cases, the first step of the photo-initiated dynamics consists of an ultrafast electron transfer from a donor to the excited flavin.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the flavin-catalyzed photooxidation of benzylic alcohol with transient absorption spectroscopy from sub-pico- to microseconds

Megerle

Wenninger

Kutta

et al. 2011

Phys. Chem. Chem. Phys.

102

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Flavin-mediated photooxidations have been described for applications in synthetic organic chemistry for some time and are claimed to be a route to the use of solar energy. We present a detailed investigation of the involved photophysical and photochemical steps in methoxybenzyl alcohol oxidation on a timescale ranging from sub-picoseconds to tens of microseconds. The results establish the flavin triplet state as the key intermediate for the photooxidation. The initial step is an electron transfer from the alcohol to the triplet state of the flavin catalyst with, followed by a proton transfer in B6 ms. In contrast, the electron transfer involving the singlet state of flavin is a loss channel. It is followed by rapid charge recombination (t = 50 ps) without significant product formation as seen when flavin is dissolved in pure benzylic alcohol. In dilute acetonitrile/water solutions of flavin and alcohol the electron transfer is mostly controlled by diffusion, though at high substrate concentrations >100 mM we also find a considerable contribution from preassociated flavin-alcohol-aggregates. The model including a productive triplet channel and a competing singlet loss channel is confirmed by the course of the photooxidation quantum yield as a function of substrate concentration: We find a maximum quantum yield of 3% at 25 mM of benzylic alcohol and significantly smaller values for both higher and lower alcohol concentrations. The observations indicate the importance to perform flavin photooxidations at optimized substrate concentrations to achieve high quantum efficiencies and provide directions for the design of flavin photocatalysts with improved performance.

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“…It is widely recognized that the relatively strong fluorescence of flavins makes observation of their spectral and photophysical properties the best tool to evaluate the physical properties of binding sites of flavoproteins. 1 The fluorescence of riboflavin (Rf) can be quenched by aromatics by different mechanisms, such as electron transfer, hydrogen bonding, hydrophobic effects, and π−π interaction. 2 Binding of riboflavin to hen egg riboflavin-binding protein results in an almost complete quenching of the riboflavin fluorescence, which is attributed to the ground-state π-stacking of the isoalloxazine ring and the aromatic residues.…”

Section: ■ Introductionmentioning

confidence: 99%

Combined Experimental and Computational Investigation of the Fluorescence Quenching of Riboflavin by Cinnamic Alcohol Chemisorbed on Silica Nanoparticles

et al. 2014

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Riboflavin (vitamin B2) is usually present in water courses, lakes, and seas and acts as a photosensitizer in the photo-oxidation of a range of contaminants. However, little is known about the interaction of this compound with aromatics sorbed on silica sediments or on suspended silica particles. This article describes the modification and characterization of silica nanoparticles by condensation of the silanol groups of the particles with E-cinnamic alcohol. The reaction was confirmed by Fourier transform infrared spectroscopy (FTIR), solid-state 13 C and 29 Si crosspolarization magic angle spinning (CPMAS) NMR, reduction of the specific surface area measured by BET, thermal analysis, and fluorescence spectroscopy. Toxicity to the marine bacteria Vibrio fischeri of the modified particles was also measured. Riboflavin fluorescence was quenched in aqueous medium in the presence of dissolved E-cinnamic alcohol or in suspensions of the modified particles. The results are interpreted in terms of formation of 1:1 complexes between the ground states of riboflavin and the free or adsorbed cinnamic alcohol. Density functional theory (DFT) calculations in aqueous medium support the existence of the complex and explain the observed quenching of riboflavin fluorescence upon addition of cinnamic alcohol without affecting the emission maximum of riboflavin. ■ INTRODUCTIONThe photochemistry and photophysics of isoalloxazines (10-substituted 2,3,4,10-tetrahydro-benzo[g]pteridine-2,4-diones), and especially flavins (7,8-dimethyl substituted isoalloxazines), are of considerable interest due to the biological relevance of these compounds. It is widely recognized that the relatively strong fluorescence of flavins makes observation of their spectral and photophysical properties the best tool to evaluate the physical properties of binding sites of flavoproteins.1 The fluorescence of riboflavin (Rf) can be quenched by aromatics by different mechanisms, such as electron transfer, hydrogen bonding, hydrophobic effects, and π−π interaction.2 Binding of riboflavin to hen egg riboflavin-binding protein results in an almost complete quenching of the riboflavin fluorescence, which is attributed to the ground-state π-stacking of the isoalloxazine ring and the aromatic residues.3 π-Stacking of riboflavin with aromatic residues and the concomitant quenching of the riboflavin fluorescence has also been reported for other riboflavin-binding proteins. 4 The remarkably low fluorescence yield of flavin adenine dinucleotide (FAD) with respect to free riboflavin was explained by the coplanar stacking of the flavin and adenine ring systems, most likely through a mechanism of photoinduced electron transfer of a nonfluorescent intramolecular ground-state complex between the isoalloxazine ring and the adenine moiety.5 Binding of Rf to salycilate ion in aqueous solution was also reported to yield a nonfluorescent complex. 6 Besides the biological relevance of Rf, this molecule is usually present in water courses, lakes, and seas 7 and acts as a p...

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Spectroscopy and photophysics of flavin related compounds: Riboflavin and iso-(6,7)-riboflavin

Cited by 74 publications

References 46 publications

Visible light induced dextran-methacrylate hydrogel formation using (−)-riboflavin vitamin B2 as a photoinitiator and L-arginine as a co-initiator

Visible light induced dextran-methacrylate hydrogel formation using (−)-riboflavin vitamin B2 as a photoinitiator and L-arginine as a co-initiator

Unraveling the flavin-catalyzed photooxidation of benzylic alcohol with transient absorption spectroscopy from sub-pico- to microseconds

Combined Experimental and Computational Investigation of the Fluorescence Quenching of Riboflavin by Cinnamic Alcohol Chemisorbed on Silica Nanoparticles

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