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Water‐Soluble Flavonol (=3‐Hydroxy‐2‐phenyl‐4 H ‐1‐benzopyran‐4‐one) Derivatives: Chemical Synthesis, Colouring, and Antioxidant Properties
Author(s) -
Alluis Bertrand,
Pérol Nathalie,
El hajji Hakima,
Dangles Olivier
Publication year - 2000
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(20000216)83:2<428::aid-hlca428>3.0.co;2-j
Subject(s) - chemistry , rutin , bathochromic shift , dpph , pigment , antioxidant , quercetin , organic chemistry , polyphenol , anthocyanin , stereochemistry , food science , quantum mechanics , fluorescence , physics
Abstract 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‐4 H ‐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‐(2,4,6‐trinitrophenyl)hydrazyl).