Sonia de Pascual-Teresa

Flavanols and Anthocyanins in Cardiovascular Health: A Review of Current Evidence

Nowadays it is accepted that natural flavonoids present in fruits and plant-derived-foods are relevant, not only for technological reasons and organoleptic properties, but also because of their potential health-promoting effects, as suggested by the available experimental and epidemiological evidence. The beneficial biological effects of these food bioactives may be driven by two of their characteristic properties: their affinity for proteins and their antioxidant activity. Over the last 15 years, numerous publications have demonstrated that besides their in vitro antioxidant capacity, certain phenolic compounds, such as anthocyanins, catechins, proanthocyanidins, and other non coloured flavonoids, may regulate different signaling pathways involved in cell survival, growth and differentiation. In this review we will update the knowledge on the cardiovascular effects of anthocyanins, catechins and proanthocyanidins, as implied by the in vitro and clinical studies on these compounds. We also review the available information on the structure, distribution and bioavailability of flavanols (monomeric catechins and proanthocyanidins) and anthocyanins, data necessary in order to understand their role in reducing risk factors and preventing cardiovascular health problems through different aspects of their bioefficacy on vascular parameters (platelet agregation, atherosclerosis, blood pressure, antioxidant status, inflammation-related markers, etc.), myocardial conditions, and whole-body metabolism (serum biochemistry, lipid profile), highlighting the need for better-designed clinical studies to improve the current knowledge on the potential health benefits of these flavonoids to cardiovascular and metabolic health.

Evaluation of the antioxidant properties of fruits

Abstract Twenty-eight different fruits were analysed for antioxidant activities using two different methods, one that determines the inhibition of ascorbate/iron-induced peroxidation of phosphatidylcholine, by means of thiobarbituric acid-reactive substances (TBARS) measurement, and another that evaluates the scavenging of the radical cation of 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) relative to Trolox C, a water-soluble vitamin E analogue. The values of the antioxidant capacities of the analysed fruits were in a wide range from 50 g to more than 5 mg for the IW 50 (dry weight causing 50% inhibition of lipidic peroxidation) and from it 406 μmol/g for the TEAC (μmol Trolox equivalents g −1 ). There was no significant correlation between antioxidant activity (IW 50 and TEAC) and the contents of flavanol of the samples. The antioxidant activities of the analysed fruits cannot only be attributed to their flavanol contents, but to the result of the action of different antioxidant compounds present in the fruits and to possible synergic and antagonist effects still unknown.

Anthocyanins: From plant to health

Anthocyanins are a group of natural occurring pigments responsible for the red-blue colour of many fruits and vegetables. Anthocyanins are of interest for two reasons because they cannot only be used in the technological field as natural colorants but also have important implications in the field of human health. Numerous studies indicate the potential effect that this family of flavonoids may have in reducing the incidence of cardiovascular disease, cancer, hyperlipidemias and other chronic diseases through the intake of anthocyanin-rich foods. This review examines existing literature in this area: from plant content and distribution to health implications, including the effect of agronomic and genetic modifications on the anthocyanin content of plants as well as other biotechnological factors and food processing. The bioavailability, metabolism, bioactivity, and epidemiology of anthocyanins will also be reviewed.

Metabolism of Anthocyanins by Human Gut Microflora and Their Influence on Gut Bacterial Growth

Consumption of anthocyanins has been related with beneficial health effects. However, bioavailability studies have shown low concentration of anthocyanins in plasma and urine. In this study, we have investigated the bacterial-dependent metabolism of malvidin-3-glucoside, gallic acid and a mixture of anthocyanins using a pH-controlled, stirred, batch-culture fermentation system reflective of the distal human large intestine conditions. Most anthocyanins have disappeared after 5 h incubation while gallic acid remained constant through the first 5 h and was almost completely degraded following 24 h of fermentation. Incubation of malvidin-3-glucoside with fecal bacteria mainly resulted in the formation of syringic acid, while the mixture of anthocyanins resulted in formation of gallic, syringic and p-coumaric acids. All the anthocyanins tested enhanced significantly the growth of Bifidobacterium spp. and Lactobacillus-Enterococcus spp. These results suggest that anthocyanins and their metabolites may exert a positive modulation of the intestinal bacterial population.

Red wine anthocyanins are rapidly absorbed in humans and affect monocyte chemoattractant protein 1 levels and antioxidant capacity of plasma

Epidemiological studies suggest that a moderate consumption of anthocyanins may be associated with protection against coronary heart disease. The main dietary sources of anthocyanins include red-coloured fruits and red wine. Although dietary anthocyanins comprise a diverse mixture of molecules, little is known how structural diversity relates to their bioavailability and biological function. The aim of the present study was to evaluate the absorption and metabolism of the 3-monoglucosides of delphinidin, cyanidin, petunidin, peonidin and malvidin in humans and to examine both the effect of consuming a red wine extract on plasma antioxidant status and on monocyte chemoattractant protein 1 production in healthy human subjects. After a 12-h overnight fast, seven healthy volunteers received 12 g of an anthocyanin extract and provided 13 blood samples in the 24 h following the test meal. Furthermore, urine was collected during this 24-h period. Anthocyanins were detected in their intact form in both plasma and urine samples. Other anthocyanin metabolites could also be detected in plasma and urine and were identified as glucuronides of peonidin and malvidin. Anthocyanins and their metabolites appeared in plasma about 30 min after ingestion of the test meal and reached their maximum value around 1.6 h later for glucosides and 2.5 h for glucuronides. Total urinary excretion of red wine anthocyanins was 0.05+/-0.01% of the administered dose within 24 h. About 94% of the excreted anthocyanins was found in urine within 6 h. In spite of the low concentration of anthocyanins found in plasma, an increase in the antioxidant capacity and a decrease in MCP-1 circulating levels in plasma were observed.

Structural diversity of anthocyanin-derived pigments in port wines

Abstract One year-old Port wine made from grapes of the Douro Valley was analysed for its anthocyanin-like pigment composition. The samples were purified by low pressure Toyopearl gel column chromatography, yielding two fractions. Fraction A was eluted with water/methanol 20% (v/v) and fraction B was eluted with methanol 100% (v/v). Structural elucidation of the pigments detected was attempted using LC/DAD-MS. Several anthocyanin-derived pigments were detected. Fraction A was mainly comprised of malvidin 3-glucoside and its pyruvic acid adducts. Additionally, other minor anthocyanin-pyruvic acid derivatives were also detected. Fraction B was shown to contain three groups of anthocyanin-derived pigments: (1) pigments in which anthocyanins are linked to a catechin unit via an ethyl linkage; (2) pigments in which anthocyanins are linked to a catechin unit or a procyanidin dimer via a vinyl linkage; (3) pigments in which anthocyanins are linked to a 4-vinylphenol group. The UV-visible spectral characteristics of most of these pigments show that they are contributing to the changing colour of Port wine from purple-red to a more orange-red hue.

Potential anti-inflammatory, anti-adhesive, anti/estrogenic, and angiotensin-converting enzyme inhibitory activities of anthocyanins and their gut metabolites

Epidemiological studies have indicated a positive association between the intake of foods rich in anthocyanins and the protection against cardiovascular diseases. Some authors have shown that anthocyanins are degraded by the gut microflora giving rise to the formation of other breakdown metabolites, which could also contribute to anthocyanin health effects. The objective of this study was to evaluate the effects of anthocyanins and their breakdown metabolites, protocatechuic, syringic, gallic, and vanillic acids, on different parameters involved in atherosclerosis, including inflammation, cell adhesion, chemotaxis, endothelial function, estrogenic/anti-estrogenic activity, and angiotensin-converting enzyme (ACE) inhibitory activity. From the assayed metabolites, only protocatechuic acid exhibited a slight inhibitory effect on NO production and TNF-α secretion in LPS-INF-γ-induced macrophages. Gallic acid caused a decrease in the secretion of MCP-1, ICAM-1, and VCAM-1 in endothelial cells. All anthocyanins showed an ACE-inhibitory activity. Delphinidin-3-glucoside, pelargonidin-3-glucoside, and gallic acid showed affinity for ERβ and pelargonidin and peonidin-3-glucosides for ERα. The current data suggest that anthocyanins and their breakdown metabolites may partly provide a protective effect against atherosclerosis that is multi-causal and involves different biochemical pathways. However, the concentrations of anthocyanins and their metabolites, as used in the present cell culture and in vitro assays mediating anti-inflammatory, anti-adhesive, anti-estrogenic, and angiotensin-converting enzyme inhibitory activities, were often manifold higher than those physiologically achievable.

Antioxidant and anti-atherogenic activities of olive oil phenolics.

The aim of the current study was to investigate the antioxidant and cellular activity of the olive oil phenolics oleuropein, tyrosol, hydroxytyrosol, and homovanillic alcohol (which is also a major metabolite of hydroxytyrosol). Well-characterized chemical and biochemical assays were used to assess the antioxidant potential of the compounds. Further experiments investigated their influence in cell culture on cytotoxic effects of hydrogen peroxide and oxidized low-density lipoprotein (LDL), nitric oxide production by activated macrophages, and secretion of chemoattractant and cell adhesion molecules by the endothelium. Inhibitory influences on in vitro platelet aggregation were also measured. The antioxidant assays indicated that homovanillic alcohol was a significantly more potent antioxidant than the other phenolics, both in chemical assays and in prolonging the lag phase of LDL oxidation. Cell culture experiments suggested that the olive oil phenolics induce a significant reduction in the secretion of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (and a trend towards a reduced secretion of monocyte chemoattractant protein-1), and protect against cytotoxic effects of hydrogen peroxide and oxidized LDL. However, no influence on nitric oxide production or platelet aggregation was evident. The data show that olive oil phenolics have biochemical and cellular actions, which, if also apparent in vivo, could exert cardioprotective effects.

Differential effects of apolipoprotein E3 and E4 on markers of oxidative status in macrophages

ApoE is secreted by macrophages at the lesion site of the atherosclerotic plaque, where it is thought to play a protective role against atherosclerosis independently of its effects on lipid metabolism. Of the three common isoforms for apoE, apoE4 is associated with higher risk of cardiovascular disease (CVD). In vitro studies have shown that recombinant apoE may act as an antioxidant in an isoform-dependent manner (E2 > E3 > E4). The oxidative status of the macrophages plays a key role in the process of atherosclerosis. In the present study the possible differential actions of apoE3 and apoE4 on several parameters of oxidative status were determined in stably transfected murine macrophages (RAW 264-7-apoE3 and - apoE4). No differences between genotypes were observed after peroxide challenge in either protection against cytotoxicity or in cell membrane oxidation, and modest differences were observed in the non-enzymatic antioxidants (glutathione and alpha-tocopherol) in apoE3 v. apoE4 macrophages. Importantly, cells secreting apoE4 showed increased membrane oxidation under basal conditions, and produced more NO and superoxide anion radicals than the apoE3 macrophages after stimulation. The present data suggest that apoE genotype influences the oxidative status of macrophages, and this could partly contribute to the higher CVD risk observed in apoE4 carriers.

Food-derived peptides stimulate mucin secretion and gene expression in intestinal cells.

In this study, the hypothesis that food-derived opioid peptides besides β-casomorphin 7 might modulate the production of mucin via a direct action on epithelial goblet cells was investigated in HT29-MTX cells used as a model of human colonic epithelium. Seven milk whey or casein peptides, a human milk peptide, and a wheat gluten-derived peptide with proved or probable ability to bind μ- or δ-opioid receptors were tested on the cell culture. Significantly increased secretion of mucins was found after exposure to six of the assayed peptides, besides the previously described β-casomorphin 7, as measured by an enzyme-linked lectin assay (ELLA). Human β-casomorphin 5 and α-lactorphin were selected to study the expression of mucin 5AC gene (MUC5AC), the HT29-MTX major secreted mucin gene. α-Lactorphin showed increased expression of MUC5AC from 4 to 24 h (up to 1.6-fold over basal level expression), although differences were statistically different only after 24 h of exposure. However, this increased expression of MUC5AC did not reach significance after cell treatment with human β-casomorphin 5. In conclusion, six food-derived peptides have been identifed with described or probable opioid activity that induce mucin secretion in HT29-MTX cells. Concretely, α-lactorphin is able to up-regulate the expression of the major secreted mucin gene encoded by these cells.