Conceição Calhau

Polyphenols and Human Health: A Prospectus

The lay press often heralds polyphenols as panacea for all sorts of diseases. The rationale is that their antioxidant activity would prevent free radical damage to macromolecules. However, basic and clinical science is showing that the reality is much more complex than this and that several issues, notably content in foodstuff, bioavailability, or in vivo antioxidant activity are yet to be resolved. We summarize the recent findings concerning the effects of polyphenols on human health, analyze the current limitations at pitfalls, and propose future directions for research.

Effects of a fish oil containing lipid emulsion on plasma phospholipid fatty acids, inflammatory markers, and clinical outcomes in septic patients: a randomized, controlled clinical trial

IntroductionThe effect of parenteral fish oil in septic patients is not widely studied. This study investigated the effects of parenteral fish oil on plasma phospholipid fatty acids, inflammatory mediators, and clinical outcomes.MethodsTwenty-five patients with systemic inflammatory response syndrome or sepsis, and predicted to need parenteral nutrition were randomized to receive either a 50:50 mixture of medium-chain fatty acids and soybean oil or a 50:40:10 mixture of medium-chain fatty acids, soybean oil and fish oil. Parenteral nutrition was administrated continuously for five days from admission. Cytokines and eicosanoids were measured in plasma and in lipopolysaccharide-stimulated whole blood culture supernatants. Fatty acids were measured in plasma phosphatidylcholine.ResultsFish oil increased eicosapentaenoic acid in plasma phosphatidylcholine (P < 0.001). Plasma interleukin (IL)-6 concentration decreased significantly more, and IL-10 significantly less, in the fish oil group (both P < 0.001). At Day 6 the ratio PO2/FiO2 was significantly higher in the fish oil group (P = 0.047) and there were fewer patients with PO2/FiO2 <200 and <300 in the fish oil group (P = 0.001 and P = 0.015, respectively). Days of ventilation, length of intensive care unit (ICU) stay and mortality were not different between the two groups. The fish oil group tended to have a shorter length of hospital stay (22 ± 7 vs. 55 ± 16 days; P = 0.079) which became significant (28 ± 9 vs. 82 ± 19 days; P = 0.044) when only surviving patients were included.ConclusionsInclusion of fish oil in parenteral nutrition provided to septic ICU patients increases plasma eicosapentaenoic acid, modifies inflammatory cytokine concentrations and improves gas exchange. These changes are associated with a tendency towards shorter length of hospital stay.Trials RegistrationClinical Trials Registration Number ISRCTN89432944

The Bioactivity of Pomegranate: Impact on Health and Disease

The aim of the present review is to discuss the cumulative evidence that suggests that pomegranate consumption possesses a diverse array of biological actions and may be helpful in the prevention of some inflammatory-mediated diseases including cancer. The pomegranate fruit can be divided into at least three parts—seeds, peel, and juice. All these components have been studied for their antioxidant properties in a chemoprevention approach. Pomegranate exerts antiproliferative, anti-invasive, and antimetastatic effects, induces apoptosis through modulation of Bcl-2 proteins, increases p21 and p27, and downregulates cyclin-cdk network. In addition, pomegranate inhibits the activation of inflammatory pathways including, but not limited to, the NFκ-B pathway. Anti-cancer effects with the most impressive data have been demonstrated so far in prostate cancer.

Xanthohumol inhibits inflammatory factor production and angiogenesis in breast cancer xenografts

Xanthohumol (XN), a natural polyphenol present in beer, is known to exert anti‐cancer effects. However, its precise mechanisms are not yet clearly defined. The aim of this study was to investigate the effect of oral administration of XN in breast cancer xenografts in nude mice. Proliferation and apoptosis were first examined in MCF7 cell cultures after incubation with XN by trypan blue exclusion assay, [3H]‐thymidine incorporation, KI67 immunostaining and TUNEL. Morphological and histological characteristics of tumours from XN‐treated or control (vehicle‐treated) mice were compared. Immunohistochemistry for proliferative, inflammatory and endothelial cell markers was performed and activation of nuclear factor kappa B (NFκB) pathway was assessed by ELISA. In vitro MCF7 cell proliferation decreased in a dose‐dependent manner. Oral administration of XN to nude mice inoculated with MCF7 cells resulted in central necrosis within tumours, reduced inflammatory cell number, focal proliferation areas, increased percentage of apoptotic cells and decreased microvessel density. Anti‐angiogenic effects of XN were further confirmed by immunoblotting for factor VIII expression in XN‐treated tumours as compared to controls. Decreased immunostaining for NFκB, phosphorylated‐inhibitor of kappa B and interleukin‐1β were also observed as well as a significant decrease in NFκB activity to 60% of control values. These novel findings indicate that XN is able to target both breast cancer and host cells, namely inflammatory and endothelial cells, suggesting its potential use as a double‐edge anti‐cancer agent. J. Cell. Biochem. 104: 1699–1707, 2008.

Absorption of anthocyanins through intestinal epithelial cells – Putative involvement of GLUT2

Anthocyanins bioavailability is a major issue regarding their biological effects and remains unclear due to few data available on this matter. This work aimed to evaluate the absorption of anthocyanins at the intestine using Caco-2 cells. Anthocyanin extract, rich in malvidin-3-glucoside, was obtained from red grape skins and tested on Caco-2 cells. The absorption of anthocyanins, in absence or presence of 1% ethanol, was detected by HPLC/DAD/LC-MS. Our results showed that this transport was significantly increased in the presence of ethanol especially after 60 min of incubation. In addition, cells that were pretreated for 96 h with anthocyanins (200 microg/mL) showed an increase of their own transport (about 50% increase). Expression of glucose transporters sodium-dependent glucose transporter 1, facilitative glucose transporters 5, and facilitative glucose transporters 2 was assessed by RT-PCR. It was found that facilitative glucose transporters 2 expression was increased (60%) in Caco-2 cells pretreated with anthocyanins, by comparison with controls. When the effect of anthocyanin extract on (3)H-2-deoxy-D-glucose uptake was tested, an inhibitory effect was observed (about 60% decrease). However, the malvidin aglycone was tested and had no effect. In conclusion, anthocyanins could be absorbed through Caco-2 cells, and can interfere with their own transport and also with glucose intestinal uptake.

Interplay between Anthocyanins and Gut Microbiota

Anthocyanins are naturally occurring compounds abundant in the human diet. Evidence has accumulated regarding the positive association of their intake with healthy biological effects. The microbiota has just been started to be considered as a metabolic organ, hence contributing to the metabolism of phenolic compounds and, consequently, to their bioavailability and the biological effects displayed by them. This review aimed to compile information regarding interaction of anthocyanins with the microbiota, from two perspectives: (i) identification of their colonic metabolites as potential bioactive molecules and (ii) their role as prebiotic agents. These perspectives are key points in anthocyanin metabolomics. Several metabolites have been identified after anthocyanin consumption with potential health benefits, in particular phenolic acids and simple phenols. On the other hand, microbiota modulation is closely related to several physiological impairments, and its modulation has been considered as a possible mechanism by which phenolic compounds may exert their effect.

Adipocyte Size and Liability to Cell Death

Obesity constitutes a serious health problem. Inflammation, which has recently been shown to follow adipocyte death, is at the basis of a series of pathogenic complications of obesity. Here we demonstrate, through modelling using the finite element method, that the bigger the adipocyte, the more fragile it becomes to rupture when submitted to common physical forces. This indicates that adipocyte size is an important determinant of cell death. Interventions to prevent adipocyte hypertrophy may, therefore, help to reduce the risk associated with obesity.

Modulation of breast cancer cell survival by aromatase inhibiting hop (Humulus lupulus L.) flavonoids

Hop flavonoids are being regarded as attractive molecules to prevent or treat certain forms of cancer. Studies have focused mainly on xanthohumol, the most abundant prenylated chalcone existing in hops extract. However, during the production of beer, or after its ingestion, xanthohumol originates different metabolites, among which isoxanthohumol and 8-prenylnaringenin. The aim of this work was to study the effect of the prenylflavonoids xanthohumol, isoxanthohumol and 8-prenylnaringenin on the breast cancer Sk-Br-3 cell line proliferation, apoptosis and activity of the enzyme aromatase (estrogen synthase). Aromatase activity was determined by a tritiated water assay, cell proliferation was assessed by [(3)H]thymidine incorporation, sulforhodamine B protein measurement and Ki-67 immunostaining and apoptosis was determined by TUNEL. Our results show that all tested prenylflavonoids were able to inhibit aromatase activity and thus, estrogen formation. Additionally, breast cancer cell line proliferation was decreased and apoptosis induced by all three compounds. The presence of 17beta-estradiol in treatment medium was able to revert the effect of the prenylflavonoids on cellular proliferation. These observations strengthen the idea that hop flavonoids may have anti-breast cancer effects and shed new light on a possible mechanism of action by which these effects occur, namely through their ability to decrease estrogen synthesis.

Flavonoid transport across RBE4 cells: A blood-brain barrier model

There is a growing interest in dietary therapeutic strategies to combat oxidative stress-induced damage to the Central Nervous System (CNS), which is associated with a number of pathophysiological processes, including Alzheimer’s and Parkinson’s diseases and cerebrovascular diseases. Identifying the mechanisms associated with phenolic neuroprotection has been delayed by the lack of information concerning the ability of these compounds to enter the CNS. The aim of this study was to evaluate the transmembrane transport of flavonoids across RBE-4 cells (an immortalized cell line of rat cerebral capillary endothelial cells) and the effect of ethanol on this transport. The detection and quantification of all of the phenolic compounds in the studied samples (basolateral media) was performed using a HPLC-DAD (Diode Array Detector). All of the tested flavonoids (catechin, quercetin and cyanidin-3-glucoside) passed across the RBE-4 cells in a time-dependent manner. This transport was not influenced by the presence of 0.1% ethanol. In conclusion, the tested flavonoids were capable of crossing this blood-brain barrier model.

Blueberry anthocyanins and pyruvic acid adducts: anticancer properties in breast cancer cell lines

The purpose of this study was to investigate the anticancer properties of an anthocyanin‐pyruvic acid adduct extract, which is being developed aiming to be further applied in the food industry. An anthocyanin extract from blueberry (extract I) and an anthocyanin‐pyruvic acid adduct extract (extract II) were tested on two breast cancer cell lines (MDA‐MB‐231 and MCF7). Proliferation was assessed by SRB assay and 3H‐thymidine incorporation. Caspase‐3 activity was determined in the presence of both extracts. Their capacity as chemoattractants and their invasive potential were also assayed.