Melanoidins from coffee and lipid peroxidation

Dietary lipid oxidation products are thought to be an important risk factor in the development of cardiovascular diseases. Lipid oxidation products may be already present in oxidized food and they may be generated during digestion of highly oxidizable food such as meat. In vitro and in vivo studies are consistent for a role of coffee high molecular weight melanoidins in the prevention of oxidative damage. Since coffee melanoidins are poorly bioavailable, the gastro-intestinal tract itself might constitute their main biological site of action where they reach high concentrations following coffee consumption. In the stomach they inhibit the peroxidation of meat lipids, decreasing the synthesis of hydroperoxides and secondary lipoxidation products. The reduction in the formation of these pro-atherogenic compounds has been shown to be followed by a decrease in their absorption in the human volunteers. The ability of coffee melanoidins to inhibit lipid peroxidation may contribute to their health benefits, since dietary oxidized lipid and advanced lipid oxidation endproducts are involved in the development of atherosclerosis and other diseases

The gastro-intestinal tract as the major site of biological action of dietary melanoidins

Emerging evidence from laboratory researches has highlighted the bioactivity of food melanoidins and melanoproteins. Whilst such studies have been carried out with different in vitro systems, information about melanoidins absorption and bio-availability are scarce. However, they are generally considered as poorly absorbable and bio-available compounds. Therefore, we present a review in which the gastro-intestinal tract is hypothesized to be the main site of action of food melanoidins and melanoproteins biological activity. We described recent data supporting this hypothesis both in vitro model systems and in vivo. Importantly, we focused this review only on the effect of melanoidins and melanoproteins extracted from food. Most of the studies had been carried out using water-soluble carbohydrate-based melanoidins isolated from different food sources (beer, barley coffee, coffee). In bakery products, melanoidins are protein-based structure (melanoproteins) which are largely insoluble in water. Dietary melanoidins and melanoproteins have been demonstrated to exert in vitro antioxidant and metal chelating ability in the gastro-intestinal tract reducing the formation of lipid hydroperoxides and advanced lipid oxidation end products during the digestion of meat. The reduction in the formation of these pro-atherogenic compounds has been shown to be followed by a decrease in their absorption in human volunteers. Food melanoidins have also shown in vitro anti-caries and prebiotic activities. We conclude by underlining the possible role of food melanoidins in the prevention of gastro-intestinal tract cancers. We hope this review will stimulate further research on food melanoidins and their biological activities in the gastro-intestinal tract

Impact of in-vitro gastro-pancreatic digestion on polyphenols and cinnamaldehyde bioaccessibility and antioxidant activity in stirred cinnamon-fortified yogurt

In this study, cinnamon powder was supplemented into yogurt as a functional ingredient. The total phenolic compounds, individual phytochemicals and radical scavenging activity of the yogurts were measured and compared with a cinnamon water extract treated in the same way as the fortified yogurt. Cinnamon-fortified yogurt displayed higher total phenolic content (P < 0.05) and higher radical scavenging activity (P < 0.05) compared to plain yogurt. Phenolic acids, flavonols and cinnamaldehyde were identified in the cinnamon-fortified yogurt. Results showed that only the 34.7% of the total phenolic compounds present in the cinnamon water extract were found in the cinnamon-fortified yogurt, the remaining being bound to milk proteins. A low recovery was also found for the individual phytochemicals. However, in-vitro digestion of the cinnamon-fortified yogurt resulted in the release of phenolic compounds from milk proteins so that at the end of the digestion the amount of phenolic compounds recovered in the cinnamon-fortified yogurt was higher than that found in the digested cinnamon water extract (P < 0.05). These results clearly showed that yogurt matrix enhance the gastro-intestinal stability and the bioaccessibility of cinnamon polyphenols. Cinnamon-fortified yogurt can be considered an important source of dietary bioaccessible polyphenols

Pomegranate ellagitannins inhibit α-glucosidase activity in vitro and reduce starch digestibility under simulated gastro-intestinal conditions

Pomegranate extract was tested for its ability to inhibit α-amylase and α-glucosidase activity. Pomegranate extract strongly inhibited rat intestinal α-glucosidase in vitro whereas it was a weak inhibitor of porcine α-amylase. The inhibitory activity was recovered in an ellagitannins-enriched fraction and punicalagin, punicalin and ellagic acid were identified as α-glucosidase inhibitors (IC50 of 140.2, 191.4 and 380.9 μmol/L, respectively). Kinetic analysis suggested that the pomegranate extract and ellagitannins inhibited α-glucosidase activity in a mixed mode. The inhibitory activity was demonstrated using an in vitro digestion system, mimicking the physiological gastro-intestinal condition, and potatoes as food rich in starch. Pre-incubation between ellagitannins and α-glucosidase increased the inhibitory activity, suggesting that they acted by binding to α-glucosidase. During digestion punicalin and punicalagin concentration decreased. Despite this loss, the pomegranate extract retained high inhibitory activity. This study suggests that pomegranate ellagitannins may inhibit α-glucosidase activity in vitro possibly affecting in vivo starch digestion

Comprehensive evaluation of phenolic profile in dark chocolate and dark chocolate enriched with Sakura green tea leaves or turmeric powder

Recently, a huge number of studies have confirmed the important role of chocolate polyphenols in human health, underlining its beneficial effects especially in the treatment of cardiovascular diseases. However, a thorough evaluation of chocolate phenolic profile is still lacking. This study aimed at a comprehensive characterization of dark chocolate phenolic profile, using non-targeted mass spectrometry identification. This approach allowed a tentative identification of 158 individual phenolic compounds: 67 were newly detected in dark chocolate, among these 38 were observed for the first time in chocolate as well as in cocoa beans or products. Ellagitannins, which have never been reported in cocoa or chocolate, represented about the 10% of the phenolic profile of dark chocolate. The enrichment of dark chocolate with Sakura green tea leaves or turmeric powder influenced and modified the phenolic profile, resulting in a phenolic concentration increase. In this way, this functional chocolate might maximize the beneficial effect of chocolate consumption, combining the positive health effects of chocolate, turmeric and green tea and, at the same time, reducing the amount of sugars and calories introduced with chocolate

Occurrence of nitric oxide synthase in Megoura viciae Buckton (Homoptera, Aphididae): an histochemical and immunohistochemical localisation

Nitric oxide (NO) is known to be involved in many physiological reactions of insects. We analysed NOS localisation in aphids of the species Megoura viciae by means of histochemical reaction for the NADPH-diaphorase activity and immunohistochemical methods for uNOS, nNOS and iNOS. The obtained data provided a complex and peculiar pattern of NOS distribution in cells and tissue of M. viciae.The histochemical reaction for NADPH-diaphorase was an indicative, but not exact marker of NOS localisation in aphids. The use of anti uNOS antiserum (frequently applied in insects) was of limited value in our specimens, whereas more satisfactory results were obtained with anti nNOS and iNOS antisera of human origin. The results of Western blot analysis confirmed the immunohistochemical ones, showing an aphid protein that reacted strongly with the polyclonal antibody anti-iNOS and anti-nNOS while a similar protein band was weakly immunoreactive with the polyclonal antibody anti-uNOS. Our results suggest that NO, prevalently synthesised by calcium/calmodulin-dependent isoform, plays important physiological roles both in adult and embryological stages of aphids. The data of principal interest was NOS presence in bacteriocytes, cells that host symbiotic prokaryotes belonging to the species Buchnera aphidicola, and in nuclei of adipocytes and gut cells

Effect of ripening and in vitro digestion on the evolution and fate of bioactive peptides in Parmigiano-Reggiano cheese

The influence of ripening and in vitro digestion on the peptidomic profile of Parmigiano-Reggiano (PR) cheeses was investigated. Ripening and in vitro digestion thoroughly modified the peptidomic profile of the three cheeses. Twenty-six bioactive peptides were identified in undigested PR. Some peptides were degraded and others released during ripening. After digestion, 52 bioactive peptides were identified. Semi-quantitative data suggested that bioactive peptides released after digestion can be clustered in 5 groups according to the ripening time. VPP and IPP peptide levels in undigested samples were in the range of 4.52–11.34 and 0.66–4.24 mg kg−1, with the highest amounts found in 18-month ripened PR. YPFPGPI peptide was absent in undigested PRs but was released after digestion, especially in the 12-month-old sample (20.18 mg kg−1). The present study suggests possible differences in bioactive peptide levels after digestion as a function of the duration of ripening of PR cheese

Protocatechuic and 3,4-Dihydroxyphenylacetic Acids Inhibit Protein Glycation by Binding Lysine through a Metal-Catalyzed Oxidative Mechanism

The mechanism of inhibition of advanced glycation end product (AGE) formation by protocatechuic acid and 3,4-dihydroxyphenylacetic acid (DHPA) has been studied using a widespread applied in vitro model system composed of bovine serum albumin (BSA) and supraphysiological glucose concentrations. Protocatechuic acid and DHPA inhibited the formation of Amadori compounds, fluorescent AGEs (IC50 = 62.1 \ub1 1.4 and 155.4 \ub1 1.1 \u3bcmol/L, respectively), and N\u3b5-(carboxymethyl)lysine (IC50 = 535.3 \ub1 1.1 and 751.2 \ub1 1.0 \u3bcmol/L, respectively). BSA was pretreated with the two phenolic acids, and the formation of BSA\u2013phenolic acid adducts was estimated by nanoflow liquid chromatography\u2013electrospray ionization\u2013quadrupole time-of-flight mass spectrometry. Results showed that the tested phenolic acids bound key sites of glycation in BSA through a metal-catalyzed oxidative mechanism. The antiglycative activity mechanism involved the formation of BSA\u2013phenolic acid adducts, and it is unlikely that this occurs in vivo. These results raise the problem to design in vitro models closer to physiological conditions to reach biologically sound conclusions

Comparative peptidomic profile and bioactivities of cooked beef, pork, chicken and turkey meat after in vitro gastro-intestinal digestion

This study was designed to investigate the potential contribution of bioactive peptides to the biological activities related to the consumption of pork, beef, chicken and turkey meat following in vitro gastro-intestinal digestion. After extraction of the peptidic fractions from digested samples, the bioactivities were evaluated by in vitro antioxidant activity as well as angiotensin-converting enzyme (ACE) and dipeptidyl peptidase-IV (DPP-IV) inhibition assays. Pork and turkey meat appeared to be the best sources of antioxidant peptides. Pork was found to be the best source of DPP-IV-inhibitory peptides whereas chicken meat supplied peptides with the highest ACE-inhibitory activity. The comprehensive analysis of the peptidomic profile of digested samples was performed by nano-LC-ESI-QTOF MS/MS analysis. A total of 217, 214, 257 and 248 peptides were identified in digested pork, beef, chicken and turkey meat, respectively. Chicken and turkey meat showed the highest similarity in peptide sequences with 202 common peptides. Sixty-two peptides matched with sequences with previously demonstrated biological activity. In particular, 35 peptides showed ACE-inhibitory activity and 23 DPP-IV inhibitory activity. Twenty-two bioactive peptides were commonly released from the different types of meat. The relative amount of identified bioactive peptides were positively correlated to the biological activities of the different digested meats. Biological significance: The present study describes for the first time a comprehensive peptide profile of four types of meat after in vitro gastro-intestinal digestion. The peptide inventory was used to identify 62 bioactive peptides with ACE- and DPPIV-inhibitory and antioxidant activities. The bioactivity analysis revealed interesting and significant differences between the studied meats. The originality of this work lay in the description of intrinsic differences in physiological functions after the ingestion of meat proteins from different species. In a context in which the current research scene relates meat consumption to the onset of chronic pathologies, this peptide profiling and bioactivity analysis shed light on the possible health benefits of peptides released from meat proteins. In fact, this paper represents a sort of detailed peptide list that may help to predict which peptides could be generated after meat intake and detectable at gastro-intestinal level. It also provides a thorough investigation of novel biological activities associated to meat protein hydrolysates, giving a new positive aspect to meat consumption

Antiproliferative Activity and Cell Metabolism of Hydroxycinnamic Acids in Human Colon Adenocarcinoma Cell Lines

In this study, we investigated the antiproliferative activity and the stability and metabolic fate of the main dietary hydroxycinnamates, using two colonic adenocarcinoma cell models (Caco-2 and SW480). Dihydrocaffeic and dihydroferulic acids were the most effective against cell proliferation in both cell lines with IC50 values of 71.7 \ub1 1.1 and 83.1 \ub1 1.1 \u3bcmol/L, respectively (P < 0.05) in Caco-2. At 200 \u3bcmol/L, caffeic and ferulic acids inhibited SW480 proliferation by 40.8 \ub1 1.6 and 59.9 \ub1 1.3%, respectively. Hydroxycinnamic acids with a catechol-type structure were degraded in Caco-2 cell medium, resulting in the production of H2O2. Intracellular Caco-2 UDP-glucuronosyltransferases and catechol-O-methyltransferases were able to form glucuronide and methyl conjugates. However, only the sulfate conjugates were detected after incubation with SW480. In addition, simple hydroxycinnamates were released from quinic and aspartic conjugates. The remarkable effect of dihydrocaffeic and dihydroferulic acids against cell proliferation is of paramount importance, since these compounds are the main metabolites detectable at the colonic level