Water-Soluble Flavonol (=3-Hydroxy-2-phenyl-4H-1-benzopyran-4-one) Derivatives: Chemical Synthesis, Colouring, and Antioxidant Properties

✍ Scribed by Bertrand Alluis; Nathalie Pérol; Hakima El hajji; Olivier Dangles

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: German
• Weight: 194 KB
• Volume: 83
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/(sici)1522-2675(20000216)83:2<428::aid-hlca428>3.0.co;2-j

✦ Synopsis

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 H 2 O-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 H 2 O-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-(2,4,6trinitrophenyl)hydrazyl).