Phenolic compounds are secondary metabolites widely spread throughout the plant kingdom that can be categorized as flavonoids and non-flavonoids. Interest in phenolic compounds has dramatically increased during the last decade due to their biological effects and promising therapeutic applications. In this review, we discuss the importance of phenolic compounds’ bioavailability to accomplish their physiological functions, and highlight main factors affecting such parameter throughout metabolism of phenolics, from absorption to excretion. Besides, we give an updated overview of the health benefits of phenolic compounds, which are mainly linked to both their direct (e.g., free-radical scavenging ability) and indirect (e.g., by stimulating activity of antioxidant enzymes) antioxidant properties. Such antioxidant actions reportedly help them to prevent chronic and oxidative stress-related disorders such as cancer, cardiovascular and neurodegenerative diseases, among others. Last, we comment on development of cutting-edge delivery systems intended to improve bioavailability and enhance stability of phenolic compounds in the human body.

Tryptophan, serotonin, and melatonin, present in Jerte Valley cherries, participate in sleep regulation and exhibit antioxidant properties. The effect of the intake of seven different Jerte Valley cherry cultivars on the sleep-wake cycle, 6-sulfatoxymelatonin levels, and urinary total antioxidant capacity in middle-aged and elderly participants was evaluated. Volunteers were subjected to actigraphic monitoring to record and display the temporal patterns of their nocturnal activity and rest. 6-sulfatoxymelatonin and total antioxidant capacity were quantified by enzyme-linked immunosorbent assay and colorimetric assay kits, respectively. The intake of each of the cherry cultivars produced beneficial effects on actual sleep time, total nocturnal activity, assumed sleep, and immobility. Also, there were significant increases in 6-sulfatoxymelatonin levels and total antioxidant capacity in urine after the intake of each cultivar. These findings suggested that the intake of Jerte Valley cherries exerted positive effect on sleep and may be seen as a potential nutraceutical tool to counteract oxidation.

Red grapes contain elevated amounts of antioxidant compounds (polyphenols) that may potentially prevent cell aging, cardiovascular disease and oxidation-related disorders. Since functional drinks are presently one of the most dynamic sectors of the market, the present work was aimed at evaluating the possible antioxidant effect of an experimental grape juice in terms of urinary 6-sulfatoxymelatonin (aMT6-s) and total antioxidant capacity in young (20 ± 10 yr-old), middle-aged (45 ± 10 yr-old) and elderly (75 ± 10 yr-old) individuals. Grapes (Vitis vinifera cv. Tempranillo) were de-stemmed, racked and pressed. The juice was subsequently stabilized by high hydrostatic pressure (HHP). Participants consumed 200 mL of grape juice twice a day (as the lunch and dinner desserts) for 5 days. First-void morning urines were collected before treatment (basal values), the day immediately after the last ingestion of juice (assay), and one day afterwards (post-assay). aMT6-s and total antioxidant capacity were quantified using commercial ELISA and colorimetric assay kits, respectively. The intake of grape juice cv. Tempranillo induced a significant increase of urinary aMT6-s and total antioxidant capacity in the three groups of age analyzed as compared to their corresponding basal and post-assay values. These functional/nutraceutical properties may be of interest for a prospective commercialization of the grape juice. The novel technology used for juice stabilization may be suitable for introducing into the market a product with high sensory and nutritional quality, as it has been shown in this study.

The Poincaré plot is a geometrical technique used to visualize and quantify the correlation between two consecutive data points in a time-series. Since the dynamics of fluctuations in physiological rhythms exhibit long-term correlation and memory, this study aimed to extend the Poincaré plot by calculating the correlation between sequential data points in a time-series, rather than between two consecutive points. By incorporating this so-called lag, we hope to integrate a temporal aspect into quantifying the correlation, to depict whether a physiological system holds prolonged association between events separated by time. In doing so, it attempts to instantaneously characterize the intrinsic behavior of a complex system. We tested this hypothesis on three different physiological time-series: heart rate variability in patients with liver cirrhosis, respiratory rhythm in asthma and body temperature fluctuation in patients with cirrhosis, to evaluate the potential application of the extended Poincaré method in clinical practice. When studying the cardiac inter-beat intervals, the extended Poincaré plot revealed a stronger autocorrelation for patients with decompensated liver cirrhosis compared to less severe cases using Pearson’s correlation coefficient. In addition, long-term variability (known as SD2 in the extended Poincaré plot) appeared as an independent prognostic variable. This holds significance by acting as a non-invasive tool to evaluate patients with chronic liver disease and potentially facilitate transplant selection as an adjuvant to traditional criteria. For asthmatics, employing the extended Poincaré plot allowed for a non-invasive tool to differentially diagnose various classifications of respiratory disease. In the respiratory inter-breath interval analysis, the receiver operating characteristic (ROC) curve provided evidence that the extension of the Poincaré plot holds a greater advantage in the classification of asthmatic patients, over the traditional Poincaré plot. Lastly, the analysis of body temperature from patients using the extended Poincaré plot helped identify inpatients from outpatients with cirrhosis. Through these analyses, the extended Poincaré plot provided unique and additional information which could potentially make a difference in clinical practice. Conclusively, the potential use of our work lies in its possible application of predicting mortality for the organ allocation procedure in patients with cirrhosis and non-invasively distinguish between atopic and non-atopic asthma.

Alterations of distal/proximal skin temperature, their gradient and their time-course were observed in patients with cirrhosis, which may contribute to their sleep disturbances.