- Preparation, Stability, and Compositions of the Crystals of Reduced Riboflavins
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Green crystals were obtained after a reduction of riboflavin (RF) with Na2S2O4.These crystals were gradually oxidized to RF when stored in air, even at -10 deg C.The emission spectra and X-ray powder diffraction analyses of the green crystals clearly showed different patterns from those of RF.The ESR spectra and number of the reduced species determined by the titration with KMnO4 supported the formation of an RF-flavosemiquinone radical (1:1) complex.Reduced riboflavin tetrabutyrate prepared according to the same procedure was too unstable for dioxygen to obtain spectroscopic data.
- Ebitani, Matsue,Kashiwagi, Hiroshi,Inoue, Masami,Nishibe, Keiichi
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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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- 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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- X-Ray Diffraction Patterns and Crystal Structures of Riboflavin Tetrabutyrate
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The X-ray diffraction patterns of two polymorpchic forms of riboflavin tetrabutyrate (RTB) powders were examined.The orange powder showed sharp peaks suggesting a well-crystallized material, while the yellow powder showed broad peaks suggesting a polymer-like material.By using the cell constants of RTB crystal, all peaks in the Debye-Sheller powder patterns of RTB were assigned.Increase of the ratio of H2O in the recrystallization solvent (MeOH-H2O) decreased the peak intensities of X-ray patterns corresponding to specific faces of RTB crystals, reflecting the direction of growth of RTB crystals in the presence of H2O.Keywords ribiflavin tetrabutyrate; polymorph; single crystal; X-ray powder analysis; stacking; hydrogen bond; IR; 1H-NMR
- Ebitani, Matsue,Kashiwagi, Hiroshi,Inoue, Masami,Enomoto, Saburo,Ishida, Toshimasa
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p. 2273 - 2275
(2007/10/02)
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