title: A planar conformation and the hydroxyl groups in the B and C rings play a pivotal role in the antioxidant capacity of quercetin and quercetin derivatives.
abstract: The polyphenol quercetin (Q) that has a high antioxidant capacity is a lead compound in the design of antioxidants. We investigated the possibility of modifying quercetin while retaining its antioxidant capacity as much as possible. To this end, the antioxidant capacities of Q, rutin, monohydroxyethyl rutinoside (monoHER) and a series of synthesized methylated Q derivatives were determined. The results confirm that the electron donating effect of the hydroxyl groups is essential. It was also found that the relatively planar structure of Q needs to be conserved. This planar conformation enables the distribution of the electron donating effect through the large conjugated π-system over the entire molecule. This is essential for the cooperation between the electron donating groups. Based on the activity of the compounds tested, it was concluded that structural modification at the 5 or 7 position is the most optimal to retain most of the antioxidant capacity of Q. This was confirmed by synthesizing and testing Q5OMe (Q6) and Q7OMe (Q7) that indeed displayed antioxidant capacities closest to Q.
authors: Department of Toxicology, Maastricht University, 6200 MD Maastricht, The Netherlands. m.moalin@maastrichtuniversity.nl
authors: Mohamed
authors: M
authors: Moalin
authors: Gino P F van
authors: GP
authors: Strijdonck
authors: Maud
authors: M
authors: Beckers
authors: Geja
authors: G
authors: Hagemen
authors: Paul
authors: P
authors: Borm
authors: Aalt
authors: A
authors: Bast
authors: Guido R M M
authors: GR
authors: Haenen
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D052160:Benzothiazoles / Q000737:chemistry; D006801:Humans; D006878:Hydroxides / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011794:Quercetin / Q000031:analogs & derivatives / Q000737:chemistry*; D012431:Rutin / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D006878:Hydroxides; D013451:Sulfonic Acids; C047368:3-methylquercetin; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D012431:Rutin; C031356:hydroxide ion; D011794:Quercetin