Effect of the co-occurring components from olive oil and thyme extracts on the antioxidant status and its bioavailability in an acute ingestion in rats† Laura Rubi ´ o, a Aida Serra, ab C.-Y. Oliver Chen, c Alba Maci ` a, a Maria-Paz Romero, a Maria-Isabel Covas, d Rosa Sol ` a e and Maria-Jos ´ e Motilva * a The aim of this work was to examine whether bioactives in thyme could enhance the antioxidant capacity of phenolics in virgin olive oil and their bioavailability in Wistar rats. After acute oral administration of extracts from olive cake (OE), thyme (TE) or their combination (OTE), blood samples were collected from 0 to 360 min. Plasma antioxidant status was analyzed by DPPH and FRAP in plasma and by SOD, CAT and GPx activities in erythrocytes. Plasma pharmacokinetics of the main metabolites of bioactives in olive oil and thyme were characterized. Plasma non-enzymatic antioxidant capacity was significantly modulated by OE, TE, and OTE in a time-, assay, and extract-dependent manner. OE, TE, and OTE all significantly decreased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity and catalase (CAT) activity was increased. Pharmacokinetic results showed that plasma concentration (C max ) of the main olive phenolic metabolites in rats fed with OTE were similar to those of OE. These results indicate that an enhanced bioavailability of olive phenolic compounds could occur in the presence of thyme, although any synergistic effect was observed in the antioxidant status when both phenolic extracts were administered. Antioxidant protection by phenolics from olive and thyme against oxidative stress occurs primarily through a direct antioxidant effect and may be related to the phenolic plasmatic metabolites. 1. Introduction Numerous studies have shown that the Mediterranean diet is protective against all-cause mortality. 1 Since oxidative stress contributes to the initiation and progression of many diseases, antioxidants in which the Mediterranean diet is rich may account partially for these benets. They exert effects via their large array of bioactions, such as free radical-scavenging, metal chelation, and enzyme modulation abilities, as well as their effects on signaling transduction pathways and gene expression. 2 Oxidative stress is dened as a condition when the excessive formation of reactive oxidant species (ROS) overwhelms antioxidant defenses. 3 Given their main functionality as an oxygen carrier in the body, erythrocytes, or red blood cells (RBC), constantly cope with an elevated ROS concentration. Fortunately, RBC are equipped with an antioxidant defense system that effi- ciently ghts against ROS attacks. The system includes SOD, CAT and GPx and other small molecule antioxidants, e.g., glutathione. Moreover, up-regulating the blood antioxidant status has been proposed as a preventative means to decrease the risk of oxidative stress related diseases such as cardiovascular diseases, diabetes, and cancer. 4 Thus, exogenous dietary phenolics could ameliorate oxidative stress either by acting as a direct radical scavenger or modulating endogenous antioxidant defenses. Phenolics in virgin olive oil were found to modulate oxidative stress in vitro 5 and in vivo, 6 mainly by acting as a free radical scavenger via their hydrogen donation and electron transfer ability, as well as metal chelating activity. 7 Since olive oil is nor- mally consumed with other foods, phytochemicals in olive oil could work with phytochemicals in other foods in the diet to modulate antioxidant defenses in an additive/synergistic manner. Flavored olive oils with herbs or species have become more common in the market in the last few years because of their added health benets to consumers beyond that of olive oil. Thyme is a common aromatic herb rich in phenolics, e.g., avonoids (tymusin, eriodictyol, xanthomycrol, 7-methyl- sudachitin), phenolic acids (the conjugated form of caffeic acid, rosmarinic acid), and monoterpenes (thymol and carvacrol). 8,9 a Department of Food Technology, XaRTA-UTPV, Escola T` ecnica Superior d'Enginyeria Agr` aria, Universitat de Lleida, Avda/Alcalde Rovira Roure 191, 25198 Lleida, Spain. E-mail: motilva@tecal.udl.cat; Fax: +34 973 702596; Tel: +34 973 702817 b School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore c Antioxidants Research Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tus University, Boston, MA 02111, USA d Cardiovascular Risk and Nutrition Research Group, IMIM-Institut de Recerca Hospital del Mar, Doctor Aiguader 88, 08003 Barcelona, Spain e Unitat de Recerca en L´ ıpids i Arteriosclerosis, CIBERDEM, St. Joan de Reus University Hospital, IISPV, Facultat de Medicina i Ci` encies de la Salut, Universitat Rovira i Virgili, C/Sant Llorenç 21, 43201 Reus, Spain † Electronic supplementary information (ESI) available. See DOI: 10.1039/c3fo60446b Cite this: Food Funct., 2014, 5, 740 Received 25th September 2013 Accepted 2nd January 2014 DOI: 10.1039/c3fo60446b www.rsc.org/foodfunction 740 | Food Funct., 2014, 5, 740–747 This journal is © The Royal Society of Chemistry 2014 Food & Function PAPER