Riboflavin Tetrabutyrate Research Articles

Separating determination of flavins using thin layer chromatography.

As a simple procedure for the separation of riboflavin tetrabutyrate and its hydrolysates, thin layer chromatography is suitable. To measure quantitatively the separated flavins, scratching out of the area of silica gel adsorbing flavin and direct application of the lumiflavin fluorescence method to the silica gel were examined. The results showed nearly 100% recovery, permitting application of the procedure of thin layer chromatography to the separating determination of synthetic riboflavin tetrabutyrate and riboflavin tetranicotinate and their partial hydrolysates as well as naturally, occurring flavins, free riboflavin, FMN and FAD.

Studies on fatty acid esters of flavins. 8. Mechanism of hydrolysis of riboflavin tetrabutyrate by pancreatic lipase.

Studies on fatty acid esters of flavins. 8. Mechanism of hydrolysis of riboflavin tetrabutyrate by pancreatic lipase.

Direct absorption of riboflavin tetrabutyrate through digestive canal.

Direct absorption of riboflavin tetrabutyrate through digestive canal.

Absorption and fluorescence spectra of riboflavin tetrabutyrate in various solvents.

Spectrophotometric and fluorimetric data for riboflavin-2′ 3′ 4′ 5′-tetrabutyrate dissolved in various solvents were reported. On changing the solvents from polar to non-polar ones, the peak of the fluorescence emission spectrum shifted to blue, and the characteristic feature of the absorption spectrum in 300–500 mμ region appeared with a minute peak at 472 mμ and a shoulder at 355 mμ. This peak and shoulder disappeared when the solvent was changed to that of polar type. These results were in good accord with that reported by Harbury et at. for 3-methyllumi-flavin, suggesting that the hydrogen bond through the third imino group, if it actually occurs, was not demonstrable by the absorption spectrum of isoalloxazine compounds in the range of 300–500 mμ. Importance of these facts in interpreting the mode of binding in flavoproteins was discussed.

ヘテロ環化合物の研究(第7報) : リボフラビンの電子的性状(1) : イソアロキサチン核の電子スペクトル リボフラビンテトラブチレート非水溶液による観察

Electronic state of flavin core of riboflavin has been studied making use of the absorption and fluorecence emission spectra of various nonaqueous solutions of riboflavin tetrabutyrate (RTB). The absorption spectra of RTB in nonpolar solvents, such as carbon tetrachloride and diethyl ether, showed two new bands or shoulders in the vicinity of 420 and 470 mμ in addition to the well-known bands (α and β maxima at about 450 and 340 mμ, respectively). While the position of the a band maximum remained unaffected, the β band shifted toward longer wave length with increasing polarity of solvent, indicating that the latter is associated with π→π* transition. Two fluorescence maxima were observed in the emission spectra of RTB in nonpolar solvents, viz. at about 500 and 520 mμ. The fluorescence maximum of the shorter wave length migrates with solvent polarity corresponding to the migration of the β absorption band maximum, and has been ascribed to monomeric form of RTB. With the increase of RTB concentration, fluorescence intensity at 520 mμ increased while that of the 500 mμ decreased, indicating that the former maximum resulted from molecular association of the solute. A vertically stacked model was proposed for the dimerized complex, taking account of the electronic map of isoalloxazine.

STUDIES ON FLAVINS IN ORGANIC SOLVENTS‐I*. SPECTRAL CHARACTERISTICS OF RIBOFLAVIN, RIBOFLAVIN TETRABUTYRATE AND LUMICHROME

Abstract— The absorption and fluorescence spectra of riboflavin, riboflavin tetrabutyrate and lumichrome have been studied in organic solvents of different polarity including ethanol, acetone, dioxane, pyridine, acetic acid and in cyclohexane‐dioxane mixtures. The molar extinction coefficients of the compounds were measured and the character of solvent sensitive changes observed in the absorption spectra are discussed. The effect of hydrogen bonding and/or intramolecular charge transfer complex are proposed as possible explanation.Changes in the shape of fluorescence emission spectra are less evident; in the case of riboflavin tetrabutyrate, mirror symmetry to the shape of the longest wavelength maximum was observed in low‐polar solvents. Quantum yields of fluorescence are higher the lower the polarity of the solvent used; the value for riboflavin tetrabutyrate is greater than for riboflavin. Changes were also observed in the fluorescence emission spectra of lumichrome in solvents of different polarity.Fairly good agreement was demonstrated for positions of the observed absorption maxima of riboflavin in 98% dioxane, riboflavin tetrabutyrate and lumichrome in 80% cyclohexane in mixture with dioxane and the values calculated from energies of molecular orbitals of flavins computed by B. Pullman and A. Pullman.