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Resumen del trabajo presentado a: "The Food Factor I Barcelona Conference", 2-4 November 2016, Barcelona (Spain)., Calendula officinalis (marigold) is an interesting source of terpenes of bioactive interest, mainly pentacyclic triterpenes (PT). Supercritical extracts of marigold (ME), in absence and presence of co-solvent (ethanol), were produced and characterized. The bioaccessibility of terpenes and the distribution of particle sizes after in vitro gastrointestinal digestion affected by the coexistence of olive oil (OO) were determined. The impact of the gastrointestinal process on the antioxidant activity of the ME was also evaluated by the DPPH assay. The major quantified compounds of the extracts in absence of co-solvent were the bioactive PT taraxasterol, lupeol, D-amyrin and β-amyrin. The total amount of quantified compounds was lower in case of the ethanol-CO2 extract. The bioaccessibility decreased in the following order: sesquiterpenes hydrocarbons > oxygenated sesquiterpenes > oxygenated triterpenes > alkanes. PT showed high values of bioaccessibility (>75%), whereas such value was lower than 50% for other compounds of the extract. A negative correlation was found between molecular properties of the compounds (logP and number of rotatable bonds) and bioaccessibility. The coexistence of ME with OO during in vitro digestion enhanced the bioaccessibility of most compounds, being closer to 100% for most PT. In agreement with these results, a higher abundance of particles of lower sizes within the aqueous micellar phase after digestion of the ME+OO were found compared with the absence of OO (most particles sizes lower than 28 ½m and 192 ½m, respectively). On the other hand, the antioxidant activity of ME increased after gastrointestinal digestion up to 50%, regardless of OO. Supercritical CO2 extraction in absence of co-solvent is the preferred procedure for producing a ME richer in PT. Furthermore, in spite of the proper bioaccessibility, the co-digestion with low levels of a typical dietary fat would be enough to reach a complete bioaccessibility of PT, due to a better dispersion of the extract in the aqueous media of digestion. Additionally, the gastrointestinal process enhances the antioxidant effect of the ME, regardless of the coexistence of oil.

This work presents the first application of total-reflection X-ray fluorescence (TXRF) spectrometry, a new and powerful alternative analytical method, to evaluation of the bioaccumulation kinetics of gold nanorods (GNRs) in various tissues upon intravenous administration in mice. The analytical parameters for developed methodology by TXRF were evaluated by means of the parallel analysis of bovine liver certified reference material samples (BCR-185R) doped with 10 μg/g gold. The average values (n = 5) achieved for gold measurements in lyophilized tissue weight were as follows: recovery 99.7%, expanded uncertainty (k = 2) 7%, repeatability 1.7%, detection limit 112 ng/g, and quantification limit 370 ng/g. The GNR bioaccumulation kinetics was analyzed in several vital mammalian organs such as liver, spleen, brain, and lung at different times. Additionally, urine samples were analyzed to study the kinetics of elimination of the GNRs by this excretion route. The main achievement was clearly differentiating two kinds of behaviors. GNRs were quickly bioaccumulated by highly vascular filtration organs such as liver and spleen, while GNRs do not show a bioaccumulation rates in brain and lung for the period of time investigated. In parallel, urine also shows a lack of GNR accumulation. TXRF has proven to be a powerful, versatile, and precise analytical technique for the evaluation of GNRs content in biological systems and, in a more general way, for any kind of metallic nanoparticles.