title: trans-Resveratrol in nutraceuticals: issues in retail quality and effectiveness.
abstract: Fourteen brands of resveratrol-containing nutraceuticals were evaluated in order to verify their actual resveratrol content and to control if their health-promoting properties are related to manufacturing quality. Products included pure resveratrol capsules or multi-ingredient formulations with standardized amounts of resveratrol and other phytochemicals. Samples were analyzed for total trans-resveratrol, flavonoids, procyanidin, polyphenol content and the results were compared with the content declared on-label. Only five out of 14 brands had near label values, compliant with Good Manufacturing Practices (GMP) requirements (95-105% content of active constituent), four products were slightly out of this range (83-111%) and three were in the 8-64% range. Two samples were below the limit of detection. The greater the difference between actual and labeled resveratrol content, the lower was the antioxidant and antiproliferative activity strength. Dietary supplements containing pure trans-resveratrol exhibited a greater induction of differentiation towards human leukemic K562 cells when compared to multicomponent products. Great differences currently exist among resveratrol food supplements commercially available and GMP-grade quality should not be taken for granted. On the other side, dosages suggested by most "pure", "high-dosage" supplements may allow a supplementation level adequate to obtain some of the purported health benefits.
authors.affiliation: Dipartimento Scienze della Vita e Biotecnologie-SVEB, UR7 Terra&Acqua Tech-Università di Ferrara, Corso Ercole I d'Este 32, 44121 Ferrara, Italy.
authors.forename: Damiano
authors.initials: D
authors.lastname: Rossi
authors.forename: Alessandra
authors.initials: A
authors.lastname: Guerrini
authors.forename: Renato
authors.initials: R
authors.lastname: Bruni
authors.forename: Eleonora
authors.initials: E
authors.lastname: Brognara
authors.forename: Monica
authors.initials: M
authors.lastname: Borgatti
authors.forename: Roberto
authors.initials: R
authors.lastname: Gambari
authors.forename: Silvia
authors.initials: S
authors.lastname: Maietti
authors.forename: Gianni
authors.initials: G
authors.lastname: Sacchetti
mesh_terms: D000975:Antioxidants / Q000032:analysis; D044946:Biflavonoids / Q000032:analysis; D002392:Catechin / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D003132:Commerce / Q000592:standards*; D019587:Dietary Supplements / Q000592:standards*; D016002:Discriminant Analysis; D041905:Erythroid Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005419:Flavonoids / Q000032:analysis; D005515:Food Labeling; D006801:Humans; D020014:K562 Cells; D016018:Least-Squares Analysis; D059808:Polyphenols / Q000032:analysis; D044945:Proanthocyanidins / Q000032:analysis; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology / Q000592:standards*
chemical_list: D000975:Antioxidants; D044946:Biflavonoids; D005419:Flavonoids; D059808:Polyphenols; D044945:Proanthocyanidins; D013267:Stilbenes; C017674:procyanidin; D002392:Catechin; D000077185:Resveratrol