The contribution of flavonoid C-ring on the DPPH free radical scavenging efficiency. A kinetic approach for the 3′,4′-hydroxy substituted members

Tsimogiannis, DI; Oreopoulou, V

dc.contributor.author	Tsimogiannis, DI	en
dc.contributor.author	Oreopoulou, V	en
dc.date.accessioned	2014-03-01T01:25:15Z
dc.date.available	2014-03-01T01:25:15Z
dc.date.issued	2006	en
dc.identifier.issn	1466-8564	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/17615
dc.subject	Antioxidant	en
dc.subject	DPPH	en
dc.subject	Flavonoids	en
dc.subject	Free radical scavenging	en
dc.subject.classification	Food Science & Technology	en
dc.subject.other	Antioxidants	en
dc.subject.other	Byproducts	en
dc.subject.other	Flavors	en
dc.subject.other	Food preservation	en
dc.subject.other	Free radical reactions	en
dc.subject.other	Nutrition	en
dc.subject.other	Rate constants	en
dc.subject.other	Agroindustrial byproducts	en
dc.subject.other	DPPH	en
dc.subject.other	Flavonoids	en
dc.subject.other	Free radical scavenging	en
dc.subject.other	Pigments	en
dc.title	The contribution of flavonoid C-ring on the DPPH free radical scavenging efficiency. A kinetic approach for the 3′,4′-hydroxy substituted members	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.ifset.2005.09.001	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.ifset.2005.09.001	en
heal.language	English	en
heal.publicationDate	2006	en
heal.abstract	5,7,3′,4′-hydroxy-substituted flavonoids are considered as very efficient radical scavengers. This study examines the effect of the structural elements of the C-ring, on the radical scavenging activity of these compounds. The impact of di-hydroxy substitution of A- or B-ring on the activity of fully substituted C-ring flavonoids was also studied. Quercetin, luteolin, taxifolin, eriodictyol, rutin, (+)-catechin, (-)-epicatechin, fisetin and kaempferol were studied during the reaction with the DPPH radical; they revealed two distinctive steps of reaction, a first rapid and a second slower. DPPH scavenging followed second order kinetics during the rapid step; stoichiometric factors and rate constants were determined. Quercetin and fisetin scavenged four radicals by each molecule, while the other flavonoids scavenged two radicals with a consequent production of B-ring diquinone. Also the rate constants were affected by C-ring structure. The kinetics of the slow step was much more complicated and the contribution of C-ring was based on stoichiometry. Industrial relevance: The oxidation of oils, fats and fat-containing foods is a major problem for the food industry, because it is directly related to economical, nutritional, flavour, safety and storage problems. The use of antioxidant compounds can slow down the process of oxidation and thereby increase the shelf-life of the products. Due to probable mutagenic and carcinogenic properties of several synthetic antioxidants, there is an increasing demand from consumers for their replacement with natural compounds of similar action. Flavonoids are plant polyphenols, which display antioxidant activity as well as several beneficial pharmacological and biochemical actions, thus could be used as natural antioxidant and upgrade the quality of a product. A better understanding of the reaction of flavonoids with free radicals would elucidate their mode of action against peroxyl radicals. The relation of structure to antioxidant activity can enhance the recovery of specific compounds from herbs or agro-industrial by-products and their exploitation as natural antioxidants. © 2005 Elsevier Ltd. All rights reserved.	en
heal.publisher	ELSEVIER SCI LTD	en
heal.journalName	Innovative Food Science and Emerging Technologies	en
dc.identifier.doi	10.1016/j.ifset.2005.09.001	en
dc.identifier.isi	ISI:000237861300019	en
dc.identifier.volume	7	en
dc.identifier.issue	1-2	en
dc.identifier.spage	140	en
dc.identifier.epage	146	en