949926-49-2Relevant academic research and scientific papers
Water-soluble flavonol (= 3-hydroxy-2-phenyl-4H-1-benzopyran-4-one) derivatives: Chemical synthesis, colouring, and antioxidant properties
Alluis, Bertrand,Perol, Nathalie,Hajji, Hakima El,Dangles, Olivier
, p. 428 - 443 (2007/10/03)
Water-soluble derivatives of rutin, a very common glycoside of quercetin (= 3,3',4',5,7-pentahydroxyflavone = 2-(3,4-dihydroxyphenyl)-3,5,7- trihydroxy-4H-1-benzopyran-4-one) and a potent plant antioxidant from the flavonol family, were synthesized by simple chemical procedures aimed at introducing carboxy or sulfo groups at the sugar moiety (Scheme 1). Such derivatives form stable molecular complexes with malvin, a polyphenolic pigment from the anthocyanin family, and thereby prove to be very effective in the enhancement (hyperchromism) and variation (bathochromism) of natural colours. The H2O-solubilizing carboxylate and sulfate groups are shown to deeply modify the enthalpy-entropy balance of the pigment-flavonol complexation (copigmentation). A molecular interpretation of the complexation-induced bathochromic shift in the pigment VIS band is proposed. Finally, the H2O-soluble rutin derivatives are shown to retain the high antioxidant ability of rutin as evidenced by their efficient trapping of the coloured radical DPPH (=2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl).
One-Electron Redox Potentials of Phenols. Hydroxy- and Aminophenols and Related Compounds of Biological Interest
Steenken, S.,Neta, P.
, p. 3661 - 3667 (2007/10/02)
The rate constants for reversible electron transfer between a series of substituted phenolate ions and anilines and various substituted phenoxyl or anilino radicals in aqueous solution were measured by observing the formation or depletion of the radicals involved.Nonequilibrium concentrations of the radicals were produced in the presence of the corresponding phenols or anilines by using the pulse radiolysis technique.The relaxation of the system to equilibrium was monitored by optical detection methods.From the equilibrium constants for one-electron transfer, the one-electron redox potentials (E2) for 38 phenolic or anilino type compounds were determined, many of which are natural products.The redox potentials are strongly influenced by electron-donating or -withdrawing substituents at the aromatic system.
