Débora Villaño

Redox Molecules and Cancer Prevention: The Importance of Understanding the Role of the Antioxidant Network

Abstract: Cancer has a complex etiology with multiple risk factors that involve the interplay between genetic and environmental influences. There is compelling evidence that dietary plant foods appear to be protective against certain type of cancers. Among a number of mechanistic hypotheses, diet-derived antioxidants have been proposed to contribute to explain these findings. However, contrasting results from intervention trials have raised strong concerns about the influence of antioxidants on human health. A vulnerable point of the research on antioxidants is the lack of information on the effect of the whole array of dietary antioxidants in cancer prevention because so far mainly single molecules have been investigated. Total antioxidant capacity (TAC) considers the single antioxidant activity as well as the synergistic interactions of the redox molecules present in complex matrixes, giving an insight into the assessment of the non-enzymatic antioxidant network. This article will outline the state of art of the research on TAC and cancer, describing the plasma non-enzymatic antioxidant network and its association with diet. The feasibility of TAC assessment as an innovative tool for investigating the association between dietary antioxidants, oxidative stress, and cancer will be also discussed.

High fat meal increase of IL-17 is prevented by ingestion of fruit juice drink in healthy overweight subjects.

An emerging role of IL-17 in the inflammatory response associated with pathogenesis of neurodegeneration has been recently suggested. However, though diet represents a key factor in the modulation of inflammatory processes, evidence is not currently available on the nutritional regulation of IL-17 in humans. In a double blind, randomized, placebo controlled, crossover study, we investigated the effect of High Fat Meal (HFM) on IL-17 circulating levels in presence of a placebo (HFM-P) or with a Fruit Juice Drink (HFM-FJD) composed of pineapple, blackcurrant and plum in fourteen healthy overweight humans. Fasting in the morning subjects ingested a test meal providing 1344 Kcal. Ingestion of HFM-P induced an inflammatory response mediated by TNF-α (p < 0.001), IL-6 (p < 0.001) and IL-17 (p < 0.01). Plasma IL-17 concentration significantly increased at 1 h (+2.6 ± 1.1 pg/ml), remaining high at 4 h (+2.98 ± 1.2 pg/ml), 6 h (+2.38 ± 0.6 pg/ml) and 8 h (+2.8 ± 0.9 pg/ml) (ANOVA for time-course p=0.009). When the HFM was consumed in the presence of the FJD a marked inhibition of IL-17 response to the HFM was observed (ANOVA between treatment p=0.037). We provided, for the first time, evidence on the role of diet in modulating IL-17 production in healthy overweight subjects.

Biomarkers of antioxidant status following ingestion of green teas at different polyphenol concentrations and antioxidant capacity in human volunteers

In a randomized cross-over study, 15 healthy volunteers consumed 500 mL of green tea (GTFT) with different solid contents (1.4, 1.6, 1.8 and 2.0 g/L) to induce a dose-response effect on plasma antioxidant capacity. Ingestion of GTFT 2.0 g/L significantly increased plasma reducing power (ferric reducing antioxidant power, FRAP) at 1 h (+2.9%; p<0.01), 2 h (+2.5%; p<0.05) and 4 h (+3.6%; p<0.01). GTFT 1.8 g/L showed statistical significance at 1 h (+4.3%; p<0.01) and 2 h (+4.4%; p<0.01), whereas GTFT 1.6 g/L was effective only at 1 h (+2.9%; p<0.01) and GTFT 1.4 g/L did not induce any changes. The maximum peak of increase in plasma FRAP for different GTFTs was clearly correlated with in vitro FRAP (R=0.778). GTFT 2.0 g/L significantly increased plasma antioxidant potential (total radical-trapping antioxidant parameter) at 1 h (+8.4%; p<0.01), 2 h (+4.4%; p<0.05) and 4 h (+5.9%; p<0.01). The effect of GTFT 1.8 g/L was evident at 1 h (+5.2%; p<0.05) and 2 h (+4.6%; p<0.05) but not at 4 h. No changes in plasma total radical-trapping antioxidant parameter were detected for GTFT at 1.6 and 1.4 g/L. An evidence for a linear correlation between GTFT antioxidant content and the extent of the antioxidant effect in vivo has been provided.

Consumption of mixed fruit-juice drink and vitamin C reduces postprandial stress induced by a high fat meal in healthy overweight subjects.

Postprandial stress induced by acute consumption of meals with a high fat content results in an increase of markers of cardiometabolic risk. Repeated acute dietary stress may induce a persistent low-grade inflammation, playing a role in the pathogenesis of functional gut diseases. This may cause an impairment of the complex immune response of the gastrointestinal mucosa, which results in a breakdown of oral tolerance. We investigated the effect of ingestion of a fruit-juice drink (FJD) composed by multiple fruit juice and extracts, green tea extracts and vitamin C on postprandial stress induced by a High Fat Meal (HFM) in healthy overweight subjects. Following a double blind, placebo controlled, cross-over design, 15 healthy overweight subjects were randomized to a HFM providing 1334 Kcal (55% fat, 30% carbohydrates and 15% proteins) in combination with 500 mL of a placebo drink (HFM-P) or a fruit-juice drink (HFM-FJD). Ingestion of HFM-P led to an increase in circulating levels of cholesterol, triglycerides, glucose, insulin, TNF-α and IL-6. Ingestion of HFM-FJD significantly reduced plasma levels of cholesterol and triglycerides, decreasing inflammatory response mediated by TNF-α and IL-6. Ingestion of a fruit-juice drink reduce markers of postprandial stress induced by a HFM.

Flavan‐3‐ols, anthocyanins, and inflammation

The process of inflammation constitutes a reactive response of the organism to tissue damage and is an important factor making part of a number of degenerative pathologies as insulin resistance, dyslipidemia, and hypertension, all of them comprised in the metabolic syndrome. There is an increasing interest in plant products rich in flavan‐3‐ols and anthocyanins because of their potential beneficial effects observed in epidemiological studies against inflammatory‐related diseases. Their anti‐inflammatory effects are exerted by modulation of cell redox status and inhibition of signaling pathways as NF‐κB activation. The effects depend on their concentrations in target tissues and hence the bioavailability pathways followed by each particular compound. In this sense, in vitro studies performed with parental compounds at doses exceeding to those found in vivo may be drawing erroneous conclusions about their real efficacy. Contradictory results have been observed in human intervention trials, which may be ascribed to the type of population studied, length of study, source of flavan‐3‐ol/anthocyanin, and dose provided. Human studies are required to confirm the positive effects found in vitro and in animal models. Future research should be focused on the understanding of dose/flavonoid intake–response relationship with pharmacokinetic studies, evaluating proper biomarkers of intake. Long‐term dietary interventions are necessary to observe effects on markers of late activation as well as the possible preventive effects of these compounds on long‐term inflammation‐related diseases.

New isotonic drinks with antioxidant and biological capacities from berries (maqui, açaí and blackthorn) and lemon juice

Abstract The aim of the study was to design new isotonic drinks with lemon juice and berries: maqui [Aristotelia chilensis (Molina) Stuntz], açaí (Euterpe oleracea Mart.) and blackthorn (Prunus spinosa L.), following on from previous research. Quality parameters – including colour (CIELab parameters), minerals, phytochemical identification and quantification by high-performance liquid chromatography with diode array detector, total phenolic content by the Folin–Ciocalteu reagent, the antioxidant capacity (ABTS+, DPPH• and assays) and biological activities (in vitro alpha-glucosidase and lipase inhibitory effects) – were tested in the samples and compared to commercially available isotonic drinks. The new isotonic blends with lemon and anthocyanins-rich berries showed an attractive colour, especially in maqui samples, which is essential for consumer acceptance. Significantly higher antioxidant and biological effects were determined in the new blends, in comparison with the commercial isotonic beverages.

Effect of ingestion of dark chocolates with similar lipid composition and different cocoa content on antioxidant and lipid status in healthy humans

The association between in vitro antioxidant capacity of dark chocolates with different cocoa percentage and the in vivo response on antioxidant status was investigated. In a randomized crossover design, 15 healthy volunteer consumed 100g of high antioxidants dark chocolate (HADC) or dark chocolate (DC). In vitro, HADC displayed a higher Total Antioxidant Capacity (TAC) than DC. In vivo, plasma TAC significantly peaked 2h after ingestion of both chocolates. TAC levels went back to zero 5h after DC ingestion whilst levels remained significantly higher for HADC. HADC induced a significantly higher urinary TAC in the 5-12h interval time than DC. No change was detected in urinary excretion of F2-isoprostanes. Plasma thiols and triacylglycerol (TG) levels significantly increased for both chocolate with a peak at 2h remaining significantly higher for DC after 5h respect to HADC. Results provide evidence of a direct association between antioxidant content of chocolate and the extent of in vivo response on plasma antioxidant capacity.

Effect of elite physical exercise by triathletes on seven catabolites of DNA oxidation

Abstract The oxidized nucleoside 8-hydroxy-2’-deoxyguanosine has been widely studied as a marker of DNA oxidation; however, data on the occurrence of other metabolites in plasma that are related to DNA damage are scarce. We have applied an improved, sensitive, robust, and reliable method, involving solid phase extraction and ultrahigh-performance liquid chromatography (UHPLC)–tandem mass spectrometry (MS/MS), to the precise quantitation of seven metabolites in the plasma of 15 elite triathletes after a 2-week training program. All compounds were eluted in the first 1.6 min, with limits of detection and quantification ranging between 0.001 and 0.3 ng.mL−1 and 0.009 and 0.6 ng.mL−1, respectively. Four compounds were detected in plasma: guanosine-3’-5’-cyclic monophosphate, 8-hydroxyguanine, 8-hydroxy-2’-deoxyguanosine, and 8-nitroguanosine. After two weeks of training, 8-hydroxyguanine exhibited the highest increase (from 0.031 ± 0.008 nM to 0.036 ± 0.012 nM) (p < 0.05), which could be related to the enhanced activity of DNA-repairing enzymes that excise this oxidized base. Increased levels of guanosine-3’-5’-cyclic monophosphate and 8-hydroxy-2’-deoxyguanosine were also observed. In contrast, levels of 8-nitroguanosine (p < 0.05) were significantly reduced, which might be a protective measure as this compound strongly stimulates the generation of superoxide radicals, and its excess is related to pathologies such as microbial (viral) infections and other inflammatory and degenerative disorders. The results obtained indicate an induced adaptive response to the increased oxidative stress related to elite training, and point to the benefits associated with regular exercise.

Optimizing elicitation and seed priming to enrich broccoli and radish sprouts in glucosinolates

Elicitation is a cheaper and socially acceptable tool for improving plant food functionality. Our objective was to optimize the treatment doses of the elicitors: methyl jasmonate (MeJA), jasmonic acid (JA) and DL-methionine (MET), in order to find a successful and feasible treatment to produce broccoli and radish sprouts with enhanced levels of health-promoting glucosinolates. Also a priming of seeds as a novel strategy to trigger the glucosinolates content was carried out with water (control), MeJA (250μM), JA (250μM) and MET (10mM) before the elicitor exogenous treatment. The results showed that almost all treatments could enhance effectively the total glucosinolates content in the sprouts, achieving the most significant increases from 34% to 100% of increase in broccoli and from 45% to 118% of increase in radish sprouts after MeJA priming and treatments. Consequently, our work demonstrates the feasibility of using elicitors, such as plant stress hormones, by priming and exogenously, as a way of increase the phytochemical profile of these sprouts to enhance their consumption in the diet.

Relationship between the Ingestion of a Polyphenol-Rich Drink, Hepcidin Hormone, and Long-Term Training

The effects of polyphenol-rich foods on the iron status of athletes, as well as the effect of physical training on the hormone hepcidin, implicated in iron metabolism, are not clear. We investigated the influence on iron metabolism of a long-term training intervention of 120 days, measuring the hepcidin concentration in the plasma of 16 elite triathletes, and the effect of the ingestion of 200 mL of either aronia-citrus juice or a placebo drink for 45 days, in a crossover design. The highest plasma hepcidin concentrations were observed at the beginning of the study (116 ± 63 nM) and levels steadily decreased until the end of the intervention (final value 10 ± 7.5 nM). Long-term training might reduce inflammation and, hence, could be responsible for the decrease in hepcidin in triathletes. Polyphenols from aronia-citrus juice did not interfere in iron absorption, as we did not observe significant differences between the intake of the placebo drink or juice with regard to hepcidin levels. Further studies are required to ascertain the time and conditions necessary to restore hepcidin levels, which reflect the iron status of triathletes.