title: Seasonal effects on bioactive compounds and antioxidant capacity of six economically important brassica vegetables.
abstract: Research on natural and bioactive compounds is increasingly focused on their effects on human health, but there are unexpectedly few studies evaluating the relationship between climate and natural antioxidants. The aim of this study was analyze the biological role of six different Brassica vegetables (Brassica oleracea L. and Brassica rapa L.) as a natural source of antioxidant compounds. The antioxidant activity may be assigned to high levels of L-ascorbic acid, total phenolics and total flavonoids of each sample. The climate seasons affected directly the concentration of bioactive components and the antioxidant activity. Broccoli inflorescences and Portuguese kale showed high antioxidant activity in Spring-Summer whilst turnip leaves did so in Summer-Winter. The Brassica vegetables can provide considerable amounts of bioactive compounds and thus may constitute an important natural source of dietary antioxidants.
authors.affiliation: CITAB⁄UTAD-Centre for the Research and Technology for Agro-Environment and Biological Sciences, Universidade de Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real, Portugal. alfredoa@utad.pt
authors.forename: Alfredo
authors.initials: A
authors.lastname: Aires
authors.forename: Conceição
authors.initials: C
authors.lastname: Fernandes
authors.forename: Rosa
authors.initials: R
authors.lastname: Carvalho
authors.forename: Richard N
authors.initials: RN
authors.lastname: Bennett
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Saavedra
authors.forename: Eduardo A S
authors.initials: EA
authors.lastname: Rosa
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000737:chemistry* / Q000494:pharmacology; D001205:Ascorbic Acid / Q000032:analysis / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000037:antagonists & inhibitors / Q000378:metabolism; D019607:Brassicaceae / Q000737:chemistry* / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology; D005609:Free Radicals; D006801:Humans; D010636:Phenols / Q000032:analysis / Q000494:pharmacology; D010851:Picrates / Q000037:antagonists & inhibitors / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry* / Q000502:physiology; D025341:Principal Component Analysis; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D012621:Seasons; D013696:Temperature; D014867:Water
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D005419:Flavonoids; D005609:Free Radicals; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D014867:Water; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid