title: Cholesterol photo-oxidation: A chemical reaction network for kinetic modeling.
abstract: In this work we studied the effect of polyunsaturated fatty acids (PUFAs) methyl esters on cholesterol photo-induced oxidation. The oxidative routes were modeled with a chemical reaction network (CRN), which represents the first application of CRN to the oxidative degradation of a food-related lipid matrix. Docosahexaenoic acid (DHA, T-I), eicosapentaenoic acid (EPA, T-II) and a mixture of both (T-III) were added to cholesterol using hematoporphyrin as sensitizer, and were exposed to a fluorescent lamp for 48h. High amounts of Type I cholesterol oxidation products (COPs) were recovered (epimers 7α- and 7β-OH, 7-keto and 25-OH), as well as 5β,6β-epoxy. Fitting the experimental data with the CRN allowed characterizing the associated kinetics. DHA and EPA exerted different effects on the oxidative process. DHA showed a protective effect to 7-hydroxy derivatives, whereas EPA enhanced side-chain oxidation and 7β-OH kinetic rates. The mixture of PUFAs increased the kinetic rates several fold, particularly for 25-OH. With respect to the control, the formation of β-epoxy was reduced, suggesting potential inhibition in the presence of PUFAs.
authors.affiliation: Department of Chemistry, Washington State University, Pullman, WA 99164-4630, USA.
authors.forename: Carlo
authors.initials: C
authors.lastname: Barnaba
authors.affiliation: Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum-Università di Bologna, Viale G. Fanin 40, 40127 Bologna, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Rodríguez-Estrada
authors.affiliation: Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum-Università di Bologna, Viale G. Fanin 40, 40127 Bologna, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lercker
authors.affiliation: UNIDA, Instituto Tecnológico de Veracruz, M.A. de Quevedo 2779, Veracruz, Ver. 91897, Mexico.
authors.forename: Hugo Sergio
authors.initials: HS
authors.lastname: García
authors.affiliation: School of Food Science, Washington State University, Pullman, WA 99164-6120, USA. Electronic address: ilce.medinameza@wsu.edu.
authors.forename: Ilce Gabriela
authors.initials: IG
authors.lastname: Medina-Meza
mesh_terms: D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D006888:Hydroxycholesterols / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D000072376:Oxysterols / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006888:Hydroxycholesterols; D000072376:Oxysterols; C007997:25-hydroxycholesterol; D002784:Cholesterol
keywords: 25-Hydroxycholesterol; 7-Ketocholesterol; Chemical reaction network; Kinetic modeling; Oxysterols