title: The Oxidative State of LDL is the Major Determinant of Anti/Prooxidant Effect of Coffee on Cu Catalysed Peroxidation.
abstract: Antioxidants exert contrasting effect on low density lipoprotein (LDL) oxidation catalysed by metals, acting as pro-oxidants under select in vitro conditions. Through our study on the effect of coffee on LDL oxidation, we identified the parameters governing this phenomenon, contributing to the comprehension of its mechanism and discovering significant implications for correct alimentary recommendations. By measuring conjugated diene formation, we have analysed the quantitative and qualitative effects exerted by an extract of roasted coffee on LDL oxidation triggered by copper sulphate. When the relative effects of different coffee concentrations were plotted against the lag time (LT) of control LDL (C-LDL), the apparently random experimental data arranged in sensible patterns: by increasing the LT the antioxidant activity of coffee decreased progressively to become prooxidant. The critical LT, at which coffee switches from antioxidant to prooxidant, increased by increasing coffee concentration. Also the contrasting results obtained following a delayed addition of coffee to the assay, arranged in a simple pattern when referred to the LT of C-LDL: the prooxidant effect decreased to become antioxidant as the LT of C-LDL increased. The dependence of coffee effect on the LT of C-LDL was influenced by LDL but not by metal catalyst concentration. These novel findings point to the oxidative state of LDL as a major parameter controlling the anti/prooxidant effect of coffee and suggest the LT of C-LDL as a potent analytical tool to express experimental data when studying the action exerted by a compound on LDL oxidation.
authors.affiliation: Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/B, 07100 Sassari, Italy.
authors.forename: Ciriaco
authors.initials: C
authors.lastname: Carru
authors.forename: Valeria
authors.initials: V
authors.lastname: Pasciu
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sotgia
authors.forename: Angelo
authors.initials: A
authors.lastname: Zinellu
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Nicoli
authors.forename: Luca
authors.initials: L
authors.lastname: Deiana
authors.forename: Bruna
authors.initials: B
authors.lastname: Tadolini
authors.forename: Bastiano
authors.initials: B
authors.lastname: Sanna
authors.forename: Bruno
authors.initials: B
authors.lastname: Masala
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Pintus