Durum wheat particle size affects starch and protein digestion in vitro.

PURPOSE: The term bioaccessibility refers to the proportion of a nutrient released from a complex food matrix during digestion and, therefore, becoming potentially available for absorption in the gastrointestinal tract. In the present study, we assessed the starch and protein bioaccessibility from a range of wheat endosperm products differing in particle size. METHODS: Five porridge meals (size A, flour, mean particle size 0.11 mm, size B, small, mean particle size 0.38 mm, size C, semolina, mean particle size 1.01 mm, size D, medium, mean particle size 1.44 mm, size E, large, mean particle size 1.95 mm) with theoretically different postprandial glycaemic responses were subjected to oral processing in vitro, followed by simulated gastric and duodenal digestion. RESULTS: A significant increase (P < 0.001) in starch degradation was observed in size A (52%) compared with size E (25%). Both sizes C and D gave less, although not significantly, digestible starch (32 and 28%, respectively). The glucose release significantly decreased as the particle size of the meal increased (92.16% detected for size A vs 47.39% for size E). In agreement with starch degradation and glucose release, size A gave the most digestible protein. CONCLUSIONS: This data provide further evidence that, by decreasing the size of wheat endosperm, starch release and glycaemic response are enhanced. We also showed that protein bioaccessibility followed a similar trend as for starch digestion. Finally, these results support the hypothesis that different degrees of starch encapsulation elicit different blood glucose responses.

Effect of anionic and cationic polyamidoamine (PAMAM) dendrimers on a model lipid membrane.

In spite of the growing variety of biological applications of dendrimer-based nanocarriers, a major problem of their potential applications in bio-medicine is related to the disruption of lipid bilayers and the cytotoxicity caused by the aggregation processes involved onto cellular membranes. With the aim to study model dendrimer-biomembrane interaction, the self-assembly processes of a mixture of charged polyamidoamine (PAMAM) dendrimers and dipalmitoylphosphatidylcholine (DPPC) lipids were investigated by means of Zeta potential analysis, Raman and x-ray scattering. Zwitterionic DPPC liposomes showed substantially different behaviors during their interaction with negatively charged (generation G=2.5) sodium carboxylate terminated (COO- Na+) dendrimers or positively charged (generation G=3.0) amino terminated (-NH2) dendrimers. More specifically the obtained results evidence the sensitive interactions between dendrimer terminals and lipid molecules at the surface of the liposome, with an enhancement of the liposome surface zeta potential, as well as in the hydrophobic region of the bilayers, where dendrimer penetration produce a perturbation of the hydrophobic alkyl chains of the bilayers. Analysis of the SAXS structure factor with a suitable model for the inter-dendrimers electrostatic potential allows an estimation of an effective charge of 15 ǀeǀ for G=2.5 and 7.6 ǀeǀ for G=3.0 PAMAM dendrimers. Only a fraction (about 1/7) of this charge contributes to the linear increase of liposome zeta-potential with increasing PAMAM/DPPC molar fraction. The findings of our investigation may be applied to rationalize the effect of the nanoparticles electrostatic interaction in solution environments for the design of new drug carriers combining dendrimeric and liposomal technology.

The interaction and binding of flavonoids to human serum albumin modify its conformation, stability and resistance against aggregation and oxidative injuries.

BACKGROUND: Interactions of ligands with proteins imply changes in the properties of the macromolecules that may deeply modify their biological activities and conformations and allow them to acquire new and, sometimes, unexpected abilities. The flavonoid phloretin has several pharmacological properties that are starting to be elucidated, one of which is the well-known inhibition of glucose transport. METHODS: The interactions of phloretin to human serum albumin have been investigated by fluorescence, UV-visible, FTIR spectroscopy, native electrophoresis, protein ligand docking studies, fluorescence and scanning electron microscopy. RESULTS: Spectroscopic investigations suggest that the flavonoid binds to human serum albumin inducing a decrease in α-helix structures as shown by deconvolution of FTIR Amide I' band. Fluorescence and displacement studies highlight modifications of environment around Trp214 with the primary binding site located in the Sudlow's site I. In the hydrophobic cavity of subdomain IIA, molecular modeling studies suggest that phloretin is in non-planar conformation and hydrogen-bonded with Ser202 and Ser454. These changes make HSA able to withstand protein degradation due to HCLO and fibrillation. GENERAL SIGNIFICANCE: Our work aims to open new perspectives as far as the binding of flavonoids to HSA are concern and shows as the properties of both compounds can be remarkable modified after the complex formation, resulting, for instance, in a protein structure much more resistant to oxidation and fibrillation. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.

In Vitro Evaluation of the Antioxidant, Cytoprotective, and Antimicrobial Properties of Essential Oil from Pistacia vera L. Variety Bronte Hull.

Although the chemical composition and biological properties of some species of the genus Pistacia has been investigated, studies on hull essential oil of Pistacia vera L. variety Bronte (HEO) are currently lacking. In this work, we have carried out an in-depth phytochemical profile elucidation by Gas Chromatography-Mass Spectrometry (GC-MS) analysis, and an evaluation of antioxidant scavenging properties of HEO, using several different in vitro methods, checking also its cytoprotective potential on lymphocytes treated with tert-butyl hydroperoxide. Moreover, the antimicrobial activity against Gram-positive and Gram-negative strains, both American Type Culture Collection (ATCC) and clinical isolates, was also investigated. GC-MS analysis highlighted the richness of this complex matrix, with the identification of 40 derivatives. The major components identified were 4-Carene (31.743%), α-Pinene (23.584%), d-Limonene (8.002%), and 3-Carene (7.731%). The HEO showed a strong iron chelating activity and was found to be markedly active against hydroxyl radical, while scarce effects were found against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Moreover, pre-treatment with HEO was observed to significantly increase the cell viability, decreasing the lactate dehydrogenase (LDH) release. HEO was bactericidal against all the tested strains at the concentration of 7.11 mg/mL, with the exception of Pseudomonas aeruginosa ATCC 9027. The obtained results demonstrate the strong free-radical scavenging activity of HEO along with remarkable cytoprotective and antimicrobial properties.

Chemistry, Pharmacology and Health Benefits of Anthocyanins.

Anthocyanins are naturally occurring molecules belonging to the flavonoid class characterized by the presence of chromophores. Apart from their well-known antioxidant activity, they show a wide variety of health-promoting properties for human health, ranging from cytoprotective, antimicrobial and antitumour activities to neuroprotective, anti-obesity and lipidomic potential, properties for which anthocyanins have been prescribed as medicines in several countries for thousands of years. Despite this, these phytochemicals have received less attention than other flavonoids, and there is still a gap in the literature, particularly regarding pharmacological and toxicological aspects. Moreover, epidemiological evidence suggests a direct correlation between anthocyanin intake and a lower incidence of chronic and degenerative diseases. In light of this, the aim of this review is to cover the current literature on anthocyanins, their biological in vitro and in vivo effects and their potential therapeutic applications, as well as their bioavailability and pharmacokinetics, all of which are essential to gain a better understanding of their biological effectiveness and potential toxicity. Copyright © 2016 John Wiley & Sons, Ltd.

The effects of processing and mastication on almond lipid bioaccessibility using novel methods of in vitro digestion modelling and micro-structural analysis.

A number of studies have demonstrated that consuming almonds increases satiety but does not result in weight gain, despite their high energy and lipid content. To understand the mechanism of almond digestion, in the present study, we investigated the bioaccessibility of lipids from masticated almonds during in vitro simulated human digestion, and determined the associated changes in cell-wall composition and cellular microstructure. The influence of processing on lipid release was assessed by using natural raw almonds (NA) and roasted almonds (RA). Masticated samples from four healthy adults (two females, two males) were exposed to a dynamic gastric model of digestion followed by simulated duodenal digestion. Between 7·8 and 11·1 % of the total lipid was released as a result of mastication, with no significant differences between the NA and RA samples. Significant digestion occurred during the in vitro gastric phase (16·4 and 15·9 %) and the in vitro duodenal phase (32·2 and 32·7 %) for the NA and RA samples, respectively. Roasting produced a smaller average particle size distribution post-mastication; however, this was not significant in terms of lipid release. Light microscopy showed major changes that occurred in the distribution of lipid in all cells after the roasting process. Further changes were observed in the surface cells of almond fragments and in fractured cells after exposure to the duodenal environment. Almond cell walls prevented lipid release from intact cells, providing a mechanism for incomplete nutrient absorption in the gut. The composition of almond cell walls was not affected by processing or simulated digestion.

Palytoxin induces functional changes of anion transport in red blood cells: metabolic impact.

Palytoxin (PTX) is classified as one of the most powerful marine biotoxins (of high molecular weight and no protein origin) because it is able to interact strongly with important cellular structures influencing their function in different biological processes. This study of the effects of PTX on red blood cells (RBC) extends the knowledge about its toxicity, which concerns not only the well-known action on Na(+)/K(+)-ATPase but also band 3 protein (B3 or AE1), the role of which is essential for anion transport and for the structure, function, and metabolic integrity of the erythrocyte. The effects of PTX on RBC can be summarized as follows: it alters the anionic flux and seriously compromises not only CO(2) transport but also the metabolic modulation centered on the oxy-deoxy cycle of hemoglobin; it stabilizes the plasma membrane by preventing lipid peroxidation; and its effect does not lead to activation of caspases 3 and 8. From what is reported in steps 2 and 3, and on the basis of the results obtained on hemolysis, methemoglobin levels, and phosphatase activity, an increase of the reducing power of the erythrocytes (RBC) in the presence of PTX clearly emerges. The results have enabled us to outline some metabolic adaptations induced in the RBC by PTX.

Resveratrol treatment induces redox stress in red blood cells: a possible role of caspase 3 in metabolism and anion transport.

Resveratrol, an important phytoalexine found in many plants, has been shown to be significantly effective in the treatment of several pathological conditions such as cancer, coronary heart disease and osteoarthritis. This study focuses on the effects of this drug on human red blood cells. In particular, we have examined the influence of resveratrol on Band 3, the anion exchanger protein, and hemoglobin as a function of the oxygenation-deoxygenation cycle. Moreover, special attention has been given to the metabolic changes imposed by caspase 3 activation. Resveratrol has proved to lower superoxide production, thereby decreasing heme-iron oxidation and saving the reducing power required for met-hemoglobin reduction. Oxygen binding experiments showed that resveratrol interacts with hemoglobin, shifting the T→R conformational transition towards the higher-affinity R state. This might contribute to altering the metabolic balance of the cell through an intensification of the pentose phosphate pathway. Moreover, at high oxygenation levels of the erythrocytic hemoglobin, resveratrol induces a significant activation of caspase 3, the action of which on Band 3 has a strong impact on cellular metabolism and anion transport.

Evaluation of Anthocyanin Profile, Antioxidant, Cytoprotective, and Anti-Angiogenic Properties of Callistemon citrinus Flowers.

Lemon bottlebrush (Callistemon citrinus (Curtis) Skeels) is one of the most common ornamental plants, diffused worldwide, and characterized by the presence of flowers with an intense red/purple coloration. There is increasing interest in the use and application of anthocyanins for their unique structural/chemical features in both food and pharmaceutical applications. RP-HPLC-DAD-ESI-MS/MS analysis of an enriched fraction of acidified methanolic extract of C. citrinus flowers allow the possibility of identifying, for the first time, the presence of four anthocyanins: cyanidin-3,5-O-diglucoside (cyanin), peonidin-3,5-O-diglucoside (peonin), cyanidin-3-O-glucoside, and cyanidin-coumaroylglucoside-pyruvic acid. Moreover, the evaluation of antioxidant and biological potential showed a remarkable activity of this fraction, able to actively scavenge DPPH, AAPH, and ABTS radicals, and to counteract the ß-carotene-bleaching. In addition, it protects human mononuclear cells from oxidative injuries and prevents angiogenesis (acting in the range of few µg/ml); furthermore, it does not show significant iron-chelating ability (up to 200 µg/mL). The easy way of cultivation, robustness, and adaptability to different environments make the flowers of this plant a useful source of anthocyanins, with remarkable health promoting properties.

Influences of flavonoids on erythrocyte membrane and metabolic implication through anionic exchange modulation.

The antioxidative activity of some natural flavonoids was analyzed against the stable free radical 2,2-diphenyl-1-picryhydrazyl. The results indicate that the scavenging power of the tested flavonols is higher than that of the synthetic antioxidants butylated hydroxyanisole and butylated hydroxytoluene; instead, the flavanones show little activity, as indicated by efficient concentration (EC50) values. Flavonoid autoxidation and interaction with Fe2+ and hydrogen peroxide were tested using erythrocyte membranes as a model. The results show that some compounds, like hesperetin, evidence a pro-oxidant activity higher than the ascorbic acid/iron reference system. The compounds with strong oxidative capability do not only influence cellular redox balance but also activate caspase-3, producing lactate dehydrogenase release and enhancing anionic exchange at the level of band 3 protein.

Derangement of erythrocytic AE1 in beta-thalassemia by caspase 3: pathogenic mechanisms and implications in red blood cell senescence.

Considering its complex molecular pathophysiology, beta-thalassemia could be a good in vivo model to study some aspects related to erythrocyte functions with potential therapeutic implications not only within the frame of this particular hemoglobinopathy but also with respect to conditions in which the cellular milieu, altered by a deranged anion exchanger, could display a significant pathogenetic role (i.e., erythrocyte senescence, complications of red cell storage, renal tubular acidosis and some abnormal protein thesaurismosis). This work evaluates the anionic influx across band 3 protein in normal and beta-thalassemic red blood cells (RBCs) and ghosts. Since redox-mediated injury is an important pathway in the destruction of beta-thalassemic RBCs, we studied the anion transport and the activity of caspase 3 in the absence and presence of t-butylhydroperoxide in order to evaluate the effect of an increase of cellular oxidative stress. Interestingly, beta-thalassemic erythrocytes show a faster rate of anion exchange than normal RBCs and absence of any modulation mechanism of anion influx. These findings led us to formulate a hypothesis about the metabolic characteristics of beta-thalassemic erythrocytes, outlining that one of the main targets of caspase 3 in RBCs is the cytoplasmic domain of band 3 protein.

Influence of L-rhamnosyl-D-glucosyl derivatives on properties and biological interaction of flavonoids.

The anti-proliferative activity of hesperetin, hesperidin, neohesperidin and rutin was evaluated on human hepatoma cell lines (Hep G2) and correlated to their antioxidant activity. The results obtained showed strong anti-proliferative effects of hesperidin and neohesperidin, considerably higher than the other two additives. Hesperetin induced caspase-3 activation, release of LDH and endogenous accumulation of putrescine. Cell cycle distribution seems to indicate that the inhibitory effects of polyphenols on cell growth could be due to G0/G1 block, and activation of apoptotic pathway in the presence of hesperetin. Our results underline also that the glycone forms show reduced scavenging activity against DPPH, but present a remarkable inhibition of cell proliferation and low cytotoxicity.

Lactate Dehydrogenase Inhibition: Biochemical Relevance and Therapeutical Potential.

Lactate dehydrogenase (LHD) is a key enzyme of anaerobic metabolism in almost all living organisms and it is also a functional checkpoint for glucose restoration during gluconeogenesis and single-stranded DNA metabolism. This enzyme has a well preserved structure during evolution and among the species, with little, but sometimes very useful, changes in the amino acid sequence, which makes it an attractive target for the design and construction of functional molecules able to modulate its catalytic potential and expression. Research has focused mainly on the selection of modulator especially as far as LDH isozymes (especially LDH-5) and lactate dehydrogenases of Plasmodium falciparum (pfLDH) are concerned. This review summarizes the recent advances in the design and development of inhibitors, pointing out their specificity and therapeutic potentials.

Effects of Isolated Isoflavones Intake on Health.

BACKGROUND: Isoflavones are naturally occurring flavonoids, commonly found in the food consumed for centuries in the East-Asian population, characterized by a structure able to exert nonsteroidal estrogen-like activity on human cells. They have attracted researcher interest all around the word, following the results obtained in epidemiological and clinical studies. The involvement of isoflavones and their metabolites in various biological processes suggests that they can influence several metabolic pathways and can influence the gene expression at epigenetic level, involving effects that probably are due to early life exposure. They show positive health effects on several diseases, especially in the prevention of coronary heart and neurological diseases, hormone-related cancers, osteoporosis, and postmenopausal symptoms. METHODS: We have performed a critical evaluation of available literature trough a structured search of bibliographic databases about isoflavones health promoting properties, risk assessment and mechanisms of action. In addition, we supplied useful information on their biochemical properties, sources and bioavailability. RESULTS: Although these molecules have been the subjects of numerous researches, their role for the wellness of the human organism remains controversial. Moreover, there are substantial inconsistencies between the results obtained by epidemiologic studies conducted on Eastern population, which found high health promoting properties, and Western clinical trials, which found much less positive effects. CONCLUSION: Further epidemiologic studies and well-designed prospective human studies are to determine the beneficial effects of isoflavones exposure, as well as establishing its safe therapeutic.

Feijoa Fruit Peel: Micro-morphological Features, Evaluation of Phytochemical Profile, and Biological Properties of Its Essential Oil.

Acca sellowiana (O. Berg) Burret (Feijoa) is an evergreen shrub, belonging to the Mirtaceae family. The aim of this study was to investigate the micromorphological features of the feijoa fruit peel and to evaluate the phytochemical profile, as well as the antioxidant, cytoprotective, and antimicrobial properties of its essential oil (EO), by several in vitro cell-free and cell-based assays. The micromorphological analysis showed several schizogenic secretory cavities, immediately below the epidermal layer. Forty compounds were identified and quantified by GC-FID and GC-MS analyses. Sesquiterpenes were the most abundant ones (76.89%), followed by monoterpene hydrocarbons (3.26%), and oxygenated monoterpenes (0.34%). The main compounds were γ-Selinene (17.39%), α-Cariophyllene (16.74%), ß-Cariophyllene (10.37%), and Germacene D (5.32%). The EO showed a strong and dose-dependent antioxidant, and free-radical scavenging activity. Furthermore, it showed cytoprotective activity on the lymphocytes, that have been pre-treated with 100 µM tert-butyl-hydroperoxide (t-BOOH), as well as a decrease in intracellular reactive oxygen species (ROS), induced by t-BOOH on erythrocytes. A preliminary antimicrobial screening against GRAM+ and GRAM- bacteria, as well as on fungi highlighted that EO showed the best activity against S. aureus and C. albicans (MIC 2.7 mg/mL). In light of these results, feijoa fruit EO could find various applications, especially in the food, nutraceutical, and pharmaceutical fields.

Trehalose: a biophysics approach to modulate the inflammatory response during endotoxic shock.

We evaluated the effects of trehalose against endotoxic shock, a condition in which the loss of bio-membrane integrity plays a pivotal role. In addition we performed a biophysics experiment by quasi elastic neutron scattering (QENS) study, to investigate whether the membrane stability effect of trehalose might be correlated with its high capability to switch-off the water diffusive dynamics and, hence, the kinetic mechanisms of interaction. Endotoxic shock was induced in male rats by a single injection of Salmonella enteritidis lipopolysaccharide (LPS; 20 mg/kg/i.p.). Thirty minutes before and 2 h after LPS injection, the animals were randomized to receive vehicle (1 ml/kg/i.p. 0.9%NaCl), sucrose (1 g/kg/i.p.) or trehalose (1 g/kg/i.p.). Mean arterial blood pressure, nuclear factor-kappaB (NF-kappaB) binding activity, Ikappa-Balpha and toll-like receptor-4 (TLR-4) activation were evaluated in both liver and lung. Plasmatic tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), interleukin-6 (IL-6) and malondialdehyde (MDA) were also investigated. We studied liver injury by means of blood alanine aminotransferase activity (ALT); inducible nitric oxide synthase (iNOS) expression, myeloperoxidase (MPO) activity and tissue edema evaluation. Lung injury was investigated by means of tissue monocyte chemoattractant protein-1 (MCP-1) levels, MPO activity, iNOS expression and edema formation. Trehalose reduced hypotension, NF-kappaB binding activity, IkappaBalpha protein loss and TLR-4 activation. In addition trehalose reduced TNF-alpha, IL-1, IL-6 and MDA levels. Trehalose also blunted liver and lung injury. QENS measurements showed also that trehalose possesses a high "switching off" capability. Sucrose did not modify endotoxic shock-induced sequelae. Trehalose blocked the inflammatory cascade triggered by endotoxin shock, stabilizing the bio-membranes and switching off the water diffusive dynamics.

The disaccharide trehalose inhibits proinflammatory phenotype activation in macrophages and prevents mortality in experimental septic shock.

Proinflammatory phenotype activation in macrophages (MPhis) after sepsis orchestrates an inflammatory response leading to multiple organ dysfunction. Trehalose preserves cell viability during exposure to a range of environmental stresses. We investigated whether trehalose may inhibit endotoxin-induced activation of the inflammatory phenotype in MPhis. Rat peritoneal MPhis were stimulated with 50 microg/mL of Salmonella enteritidis lipopolysaccharide (LPS). Stimulated MPhis were coincubated with trehalose (25, 50, and 100 mmol), sucrose (100 mmol), or RPMI alone. Macrophages cultures were used for Western blot analysis of extracellular-regulated kinase, c-jun-N terminal kinase, and inducible nitric oxide synthase; interleukin (IL) 1beta, IL-6, and tumor necrosis factor alpha (TNF-alpha) gene expression by real-time reverse transcriptase-polymerase chain reaction, and supernatants for measuring the release of inflammatory cytokines and nitrite content. In vitro trehalose significantly blunted LPS-induced extracellular-regulated kinase (LPS = 21 +/- 6 integrated intensity; LPS + trehalose 100 mmol = 2 +/- 0.3 integrated intensity), c-jun-N terminal kinase (LPS = 15 +/- 5 integrated intensity; LPS + trehalose 100 mmol = 3.5 +/- 0.9 integrated intensity), and inducible nitric oxide synthase activation (LPS = 12 +/- 3 integrated intensity; LPS + trehalose 100 mmol = 1 +/- 0.09 integrated intensity), blunted IL-1beta (LPS = 5 +/- 1.9 n-folds/beta-actin; LPS + trehalose 100 mmol = 1.5 +/- 0.8 n-folds/beta-actin), IL-6 (LPS = 4 +/- 1.5 n-folds/beta-actin; LPS + trehalose 100 mmol = 1.4 +/- 0.5 n-folds/beta-actin), and TNF-alpha (LPS = 4.2 +/- 1.6 n-folds/beta-actin; LPS + trehalose 100 mmol = 1.1 +/- 0.7 n-folds/beta-actin) gene expression, and markedly reduced the release of inflammatory cytokines and nitrite content. Furthermore, in vivo trehalose prevented mortality in rats challenged with a lethal dose (20 mg/kg; LD90) of LPS (80% survival rate and 70% survival rate 24 and 72 h after LPS injection, respectively) and reduced serum TNF-alpha. Sucrose did not modified inflammatory phenotype in vitro nor in vivo protected against endotoxin-induced mortality. Our study suggests that trehalose inhibits proinflammatory phenotype activation in MPhis and prevents endotoxin-induced mortality.

Proanthocyanidins and hydrolysable tannins: occurrence, dietary intake and pharmacological effects.

Tannins are a heterogeneous group of high MW, water-soluble, polyphenolic compounds, naturally present in cereals, leguminous seeds and, predominantly, in many fruits and vegetables, where they provide protection against a wide range of biotic and abiotic stressors. Tannins exert several pharmacological effects, including antioxidant and free radical scavenging activity as well as antimicrobial, anti-cancer, anti-nutritional and cardio-protective properties. They also seem to exert beneficial effects on metabolic disorders and prevent the onset of several oxidative stress-related diseases. Although the bioavailability and pharmacokinetic data for these phytochemicals are still sparse, gut absorption of these compounds seems to be inversely correlated with the degree of polymerization. Further studies are mandatory to better clarify how these molecules and their metabolites are able to cross the intestinal barrier in order to exert their biological properties. This review summarizes the current literature on tannins, focusing on the main, recently proposed mechanisms of action that underlie their pharmacological and disease-prevention properties, as well as their bioavailability, safety and toxicology. LINKED ARTICLES: This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Sequestering ability to Cu2+ of a new bodipy-based dye and its behavior as in vitro fluorescent sensor.

A Bodipy (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) derivative has been conceived and synthesized starting from l-aspartic acid, as a selective turn-off sensor of Cu2+ ions. Its acid-base properties were determined to study the formation of metal/sensor complex species by titration of solutions each containing a different metal ion, such as Cu2+, Ca2+, Zn2+, Pb2+ and Hg2+ and different metal/sensor ratios. The speciation models allowed us to simulate the distribution of the metal/sensor complex species at the normal concentrations of the corresponding metals present in biological fluids. The distribution diagrams, obtained by varying the concentration of sensor 1, clearly indicate that sensor 1 responds selectively to Cu2+ at micromolar concentrations, even in the presence of other more abundant metal cations Ca2+. Finally, we analyzed the cellular uptake of sensor 1 on human erythrocytes and its ability to chelate Cu2+ in the cellular environment. Results indicate that it crosses the plasmatic membrane and colors the cells of a bright fluorescent red. Exposing the fluorescent cells to Cu2+ results in a complete cellular photobleaching of the red fluorescence, indicating that sensor 1 is able to detect metal changes in the cytosolic environment.

Flavanones: Citrus phytochemical with health-promoting properties.

Citrus fruit and juices represent one of the main sources of compounds with a high potential for health promoting properties. Among these compounds, flavanones (such as hesperetin, naringenin, eriodictyol, isosakuranetin, and their respective glycosides), which occur in quantities ranging from ∼180 to 740 mg/L (depending on the Citrus species and cultivar) are responsible for many biological activities. These compounds support and enhance the body's defenses against oxidative stress and help the organism in the prevention of cardiovascular diseases, atherosclerosis, and cancer. Moreover, among other properties, they also show anti-inflammatory, antiviral, and antimicrobial activities. This review analyzes the biochemistry, pharmacology, and biology of Citrus flavanones, emphasizing the occurrence in Citrus fruits and juices and their bioavailability, structure-function correlations and ability to modulate signal cascades both in vitro and in vivo. © 2017 BioFactors, 43(4):495-506, 2017.