title: Role of catechins in the antioxidant capacity of an active film containing green tea, green coffee, and grapefruit extracts.
abstract: The oxygen radical absorbance capacity (ORAC) method was used to characterize the antioxidant capacity of natural extracts of green tea, green coffee, and grapefruit. These natural extracts were incorporated into a plastic film layer, which was subsequently subjected to a free radical gas stream in order to determine the antioxidant capacity directly in the active film. The green tea extract (GTE) afforded the strongest antioxidant activity. To identify the active compounds in the extract, concentration of the diverse catechins in samples were determined by HPLC-UV analysis. The results showed that the content of catechins in the GTE is around 77% (w/w), the major components being (-)-epigallocatechin gallate, (-)-epicatechin gallate, and (-)-epicatechin. A variation in the concentration profile of catechins was detected during the oxidation process. The chromatographic study demonstrated that (-)-gallocatechin, (-)- epigallocatechin, (+)-catechin, and (-)-catechin gallate exhibited the most radical scavenging.
authors.affiliation: Department of Analytical Chemistry, Aragon Institute of Engineering Research I3A,  CPS-University of Zaragoza , Torres Quevedo Building, María de Luna Street 3, E-50018 Zaragoza, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Colon
authors.forename: C
authors.initials: C
authors.lastname: Nerin
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D032083:Citrus paradisi / Q000737:chemistry*; D040503:Coffea / Q000737:chemistry*; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D002392:Catechin