On the bioavailability of flavanols and anthocyanins: Flavanol–anthocyanin dimers Iva Fernandes, Frederico Nave, Rui Gonçalves, Victor de Freitas, Nuno Mateus ⇑ Chemistry Investigation Centre (CIQ), Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal article info Article history: Received 7 March 2012 Received in revised form 27 April 2012 Accepted 2 May 2012 Available online 14 May 2012 Keywords: Anthocyanin Flavanol Caco-2 Bioavailability Procyanidin abstract The bioavailability of flavanols, anthocyanins and anthocyanin-derived pigments like flavanol–anthocy- anin dimers already reported to occur in food products is a major unsolved issue. The absorption of the flavanol–anthocyanin dimer (+)-catechin-(4,8)-malvidin-3-O-glucoside (Cat–Mv3glc) through Caco-2 cells was assessed by performing transepithelial transport assays. The ability of Cat–Mv3glc to cross Caco-2 cells was compared with that of malvidin-3-glucoside (Mv3glc), (+)-catechin (Cat) and procyani- din B3 (Cat–Cat), in order to evaluate the influence of some structural features on the transport effi- ciency. The flavanol–anthocyanin dimer was absorbed in this intestinal model although with a lower efficiency than the monomers Cat and Mv3glc. On the other hand, Cat–Mv3glc was found to cross the intestinal barrier model more significantly than Cat–Cat. This feature may be related to the presence of the glucose moiety in its structure. Overall, this study brings more insights into the bioavailability of anthocyanins and flavanols and represents the first report on the bioavailability of flavanol– anthocyanins. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Flavanols and anthocyanins constitute two major classes of flavonoids that occur in nature arising from plant secondary metabolism. The daily intake of flavanols including catechins, pro- anthocyanidin dimers and trimers has been estimated to be 18–50 mg/d, with the main sources being tea, chocolate, apples, pears, grapes, and red wine (Arts, van de Putte, & Hollman, 2000a, 2000b). Flavanols are biologically active molecules that have a wide range of effects and are known as very strong antiox- idants that can scavenge various forms of free radicals (Ricardo da Silva, Darmon, Fernandez, & Mitjavila, 1991; Saint-Cricq de Gaul- ejac, Provost, & Vivas, 1999). They may be involved in the preven- tion of cardiovascular diseases, probably through their ability to inhibit oxidation of low density lipoprotein (LDL), to lower the plasma cholesterol level, and to prevent platelet aggregation (Jeong & Kong, 2004). In addition, there is increasing evidence of the can- cer chemopreventive properties of catechins and procyanidins (Jeong & Kong, 2004; Santos-Buelga & Scalbert, 2000). Anthocyanins constitute the largest group of water-soluble pig- ments in the plant kingdom, being responsible for the colours dis- played by many flowers, fruits and leaves. These pigments are usually present in red fruits but they also occur in vegetables, roots, legumes and cereals (Clifford, 2000). Pure anthocyanins or anthocyanin-rich extracts have been found to play a role in the prevention of cardiovascular diseases and to be involved in several different events, such as the prevention of DNA damage, oestrogen- ic activity, enzymatic inhibition, anti-inflammation response and lipid peroxidation inhibition (Liu, Lee, Shih, Chyau, & Wang, 2008). In recent years, more attention has been paid to the putative anti-tumoral properties of anthocyanins and anthocyanin extracts (Faria et al., 2010; Fernandes et al., 2010; Li et al., 2009). Due to their high chemical reactivity, anthocyanins may also be ingested as anthocyanin-derived pigments. Direct reactions be- tween anthocyanins and flavanols have already been demon- strated in model solutions (Dueñas, Fulcrand, & Cheynier, 2006; Vivar-Quintana, Santos-Buelga, Francia-Aricha, & Rivas-Gonzalo, 1999) and food matrices, especially red wine, where these com- pounds play an important role in their colour (Remy, Fulcrand, Labarbe, Cheynier, & Moutounet, 2000). These pigments are usu- ally associated with reactions taking place during processing and storage of plant-derived foods and beverages. Indeed, these com- pounds have already been identified through chromatographic procedures in strawberries (Fossen, Rayyan, & Andersen, 2004), pomegranate juice (Sentandreu, Navarro, & Sendra, 2010), beans (González-Paramás et al., 2006), grape skins (González-Paramás et al., 2006) and purple corn (González-Paramás et al., 2006). The detection of these pigments in plant extracts may suggest that they are natural pigments and not products exclusively formed during storage and ageing of processed foods and beverages, as previously 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2012.05.037 Abbreviations: Mv3glc, malvidin-3-glucoside; Cat, (+)-catechin; Cat–Cat, (+)-catechin-(4a ? 8)-(+)-catechin; Cat–Mv3glc, (+)-catechin-(4,8)-malvidin-3-O- glucoside. ⇑ Corresponding author. Tel.: +351 220402562. E-mail address: nbmateus@fc.up.pt (N. Mateus). Food Chemistry 135 (2012) 812–818 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem