Naturally occurring anthocyanin cyanidin-3-rutinoside possesses inherent vasorelaxant actions and prevents methylglyoxal-induced vascular dysfunction in rat aorta and mesenteric arterial bed

Dietary glycation compounds - implications for human health

The term "glycation compounds" comprises a wide range of structurally diverse compounds that are formed endogenously and in food via the Maillard reaction, a chemical reaction between reducing sugars and amino acids. Glycation compounds produced endogenously are considered to contribute to a range of diseases. This has led to the hypothesis that glycation compounds present in food may also cause adverse effects and thus pose a nutritional risk to human health. In this work, the Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) summarized data on formation, occurrence, exposure and toxicity of glycation compounds (Part A) and systematically assessed potential associations between dietary intake of defined glycation compounds and disease, including allergy, diabetes, cardiovascular and renal disease, gut/gastrotoxicity, brain/cognitive impairment and cancer (Part B). A systematic search in Pubmed (Medline), Scopus and Web of Science using a combination of keywords defining individual glycation compounds and relevant disease patterns linked to the subject area of food, nutrition and diet retrieved 253 original publications relevant to the research question. Of these, only 192 were found to comply with previously defined quality criteria and were thus considered suitable to assess potential health risks of dietary glycation compounds. For each adverse health effect considered in this assessment, however, only limited numbers of human, animal and in vitro studies were identified. While studies in humans were often limited due to small cohort size, short study duration, and confounders, experimental studies in animals that allow for controlled exposure to individual glycation compounds provided some evidence for impaired glucose tolerance, insulin resistance, cardiovascular effects and renal injury in response to oral exposure to dicarbonyl compounds, albeit at dose levels by far exceeding estimated human exposures. The overall database was generally inconsistent or inconclusive. Based on this systematic review, the SKLM concludes that there is at present no convincing evidence for a causal association between dietary intake of glycation compounds and adverse health effects.

Anthocyanins in Vascular Health and Disease: Mechanisms of Action and Therapeutic Potential

ABSTRACT

Unhealthy lifestyles have placed a significant burden on individuals' cardiovascular health. Anthocyanins are water-soluble flavonoid pigments found in a wide array of common foods and fruits. Anthocyanins have the potential to contribute to the prevention and treatment of cardiovascular disease by improving lipid profiles and vascular function, reducing blood glucose levels and blood pressure, and inhibiting inflammation. These actions have been demonstrated in numerous clinical and preclinical studies. At the cellular and molecular level, anthocyanins and their metabolites could protect endothelial cells from senescence, apoptosis, and inflammation by activating the phosphoinositide 3-kinase/protein kinase B/endothelial nitric oxide synthases, silent information regulator 1 (SIRT1), or nuclear factor erythroid2-related factor 2 pathways and inhibiting the nuclear factor kappa B, Bax, or P38 mitogen-activated protein kinase pathways. Furthermore, anthocyanins prevent vascular smooth muscle cell from platelet-derived growth factor -induced or tumor necrosis factor-α-induced proliferation and migration by inhibiting the focal adhesion kinase and extracellular regulated protein kinases signaling pathways. Anthocyanins could also attenuate vascular inflammation by reducing the formation of oxidized lipids, preventing leukocyte adhesion and infiltration of the vessel wall, and macrophage phagocytosis of deposited lipids through reducing the expression of cluster of differentiation 36 and increasing the expression of ATP-binding cassette subfamily A member 1 and ATP-binding cassette subfamily G member 1. At the same time, anthocyanins could lower the risk of thrombosis by inhibiting platelet activation and aggregation through down-regulating P-selectin, transforming growth factor-1, and CD40L. Thus, the development of anthocyanin-based supplements or derivative drugs could provide new therapeutic approaches to the prevention and treatment of vascular diseases.

A 90-day Sub-chronic Oral Toxicity Assessment of Mulberry Extract in Sprague Dawley Rats

Mulberry extract from Fructus Mori contains an anthocyanin pigment and has been widely used as a food additive in China and other Eastern Asian countries. Only few research has been done on toxicological profiling of mulberry extract for its safety evaluation; however, the data is inconclusive. In the current study, mulberry extract of 4200, 1400, or 466 mg/kg were orally administrated to Sprague Dawley rats for 90 consecutive days followed by a recovery period of 28 days. No abnormalities were detected in body weights, food intake, ophthalmological, hematological, coagulation, clinical chemistry, and organ weights parameters. Discoloration of urine (red, purple, and brown) and feces (black), along with bedding material (purple) were observed in the 4200 mg/kg group. Further, microscopic examination revealed brown granules in the renal tubular cells for rats in 4200 and 1400 mg/kg groups. Since these changes were associated with excretory effect of the extract, the No Observed Adverse Effect Level was determined to be 4200 mg/kg, which was equivalent to the 1058.5 mg/kg of anthocyanin.

Bioactive Compounds and Their Effect on Blood Pressure-A Review

Elevated blood pressure affects a great part of the elderly population and is the leading risk factor for cardiovascular disease. New approaches have been taken in the fight against this growing problem, in the form of diets (Mediterranean, Dietary Approaches to Stop Hypertension (DASH) and intermittent fasting). Recent research has shown the promising results regarding diets and their effect on the prevention and improvement of elevated blood pressure. This review attempts to take this a step further, reviewing 26 studies in the search for dietary elements that may be causing this improvement. Although good evidence was found in favor of lycopene, Docosahexaenoic acid (DHA), fiber and anthocyanin, further evidence is needed before any conclusions can be made. In contrast, the evidence shows that licorice increases blood pressure.

Cyanidin Attenuates Methylglyoxal-Induced Oxidative Stress and Apoptosis in INS-1 Pancreatic β-Cells by Increasing Glyoxalase-1 Activity

Recently, the mechanisms responsible for anti-glycation activity of cyanidin and its derivatives on the inhibition of methylglyoxal (MG)-induced protein glycation and advanced glycation-end products (AGEs) as well as oxidative DNA damage were reported. In this study, we investigated the protective effect of cyanidin against MG-induced oxidative stress and apoptosis in rat INS-1 pancreatic β-cells. Exposure of cells to cytotoxic levels of MG (500 µM) for 12 h caused a significant reduction in cell viability. However, the pretreatment of cells with cyanidin alone (6.25–100 μM) for 12 h, or cotreatment of cells with cyanidin (3.13–100 μM) and MG, protected against cell cytotoxicity. In the cotreatment condition, cyanidin (33.3 and 100 μM) also decreased MG-induced apoptosis as determined by caspase-3 activity. Furthermore, INS-1 cells treated with MG increased the generation of reactive oxygen species (ROS) during a 6 h exposure. The MG-induced increase in ROS production was inhibited by cyanidin (33.3 and 100 μM) after 3 h stimulation. Furthermore, MG diminished the activity of glyoxalase 1 (Glo-1) and its gene expression as well as the level of total glutathione. In contrast, cyanidin reversed the inhibitory effect of MG on Glo-1 activity and glutathione levels. Interestingly, cyanidin alone was capable of increasing Glo-1 activity and glutathione levels without affecting Glo-1 mRNA expression. These findings suggest that cyanidin exerts a protective effect against MG-induced oxidative stress and apoptosis in pancreatic β-cells by increasing the activity of Glo-1.

A New Italian Purple Corn Variety (Moradyn) Byproduct Extract: Antiglycative and Hypoglycemic In Vitro Activities and Preliminary Bioaccessibility Studies

The reuse of byproducts from agricultural and food industries represents the key factor in a circular economy, whose interest has grown in the last two decades. Thus, the extraction of bioactives from agro-industrial byproducts is a potential source of valuable molecules. The aim of this work was to investigate the in vitro capacity of byproducts from a new Italian corn variety, named Moradyn, to inhibit the accumulation of advanced glycation end products (AGEs) involved in several chronic age-related disorders. In addition, the hypoglycemic effect of Moradyn was tested by in vitro enzymatic systems. A Moradyn phytocomplex and its purified anthocyanin fraction were able to inhibit fructosamine formation and exhibited antiglycative properties when tested using BSA-sugars and BSA-methylglyoxal assays. These properties could be attributed to the polyphenols, mainly anthocyanins and flavonols, detected by RP-HPLC-DAD-ESI-MSⁿ. Finally, a Moradyn phytocomplex was submitted to a simulated in vitro digestion process to study its bioaccessibility. Moradyn could be considered as a promising food ingredient in the context of typical type 2 diabetes risk factors and the study will continue in the optimization of the ideal formulation to preserve its bioactivities from digestion.

New flavonoid-based compound synthesis strategy for antihypertensive drug development

Hypertension is one of the leading causes of mortality in relation to the cardiovascular conditions and easily the most overlooked and poorly managed disease in mankind. With well over 200 drugs available in the market globally, there is still an urgency to search for antihypertensive alternatives due to the subpar efficacy and unwarranted side effects of the current choices. Present studies reported over 250 types of plant-derived compounds were being investigated for potential pharmacological effects on the vasculature in the last 3 decades. There were numerous literatures that claimed various compounds exhibiting vasorelaxant properties to a certain extent with low numbers of these compounds being successfully adapted into the current medicinal practice for treatment of hypertension. The issue is the scarcity of reviews that summarizes the discovery of this field and the lack of thorough comparison of these compounds to identify which of these vasodilators should be the next face of hypertension management. Thus, this review is aiming towards identifying the relationship between a major class of plant-derived compounds, flavonoid's activity as a vasodilator with their signalling pathways and their structural characteristics according to their vasorelaxant properties. Interestingly, we found that both nitric oxide and voltage-operated calcium channels pathways, and two of the flavonoid's structural characteristics play crucial roles in eliciting strong vasorelaxant effects. We have faith that the insights of this review will serve as a reference for those researching similar topics in the future and potentially lead to the development of more promising antihypertensive alternative.

Compared Phenolic Compound Contents of 22 Commercial Fruit and Vegetable Juices: Relationship to ex-vivo Vascular Reactivity and Potential in vivo Projection

The real impact of polyphenol-rich vegetable and fruit juice intake on cardiovascular health remains a matter of controversy. In the present study, rat aorta segments immersed in an organ bath (OB) were used to explore whether the total polyphenol content and/or individual phenolic compound contents of 22 commercial vegetable (n = 3) and fruit juices [(citrus (n = 5), berries (n = 10), apple (n = 2), pineapple (n = 2)] might be associated with vascular tone. Red juices (particularly blackcurrant) and lemon juice caused the most marked vasorelaxation, its amplitude being endothelium dependent or not according to the volume ratio of juice to initial OB solution V_juice/V_OBS). At volume ratios 5% and 10%, both the juice and OB total polyphenol for all juices and total anthocyanin contents for berry juices significantly correlated with aorta vasorelaxation intensity. This was not the case for total or individual flavonols (except kaempferol) or for total or individual flavanols (except epigallocatechin gallate). If one relates our measured concentrations of individual phenolic compounds in OB to what is known about their physiological concentrations, and given our evidenced correlations between compound concentrations and vasorelaxation intensity, kaempferol, epigallocatechin gallate and peonidin-3-O-glucoside seem to emerge as the interesting phenolic compounds likely to be responsible for the potent vasorelaxation observed with fruit juices, and more particularly blackcurrant ones. Clinical investigation is required, however, to confirm our observations.

Cyanidin-3-rutinoside acts as a natural inhibitor of intestinal lipid digestion and absorption

BACKGROUND

Cyanidin-3-rutinoside (C3R), a naturally occurring anthocyanin, possesses anti-oxidant, anti-hyperglycemic, anti-glycation and cardioprotective properties. However, its mechanisms responsible for anti-hyperlipidemic activity have not been fully identified. The aim of the study was to investigate the lipid-lowering mechanisms of C3R through inhibition of lipid digestion and absorption in vitro.

METHODS

The inhibitory activity of C3R against pancreatic lipase and cholesterol esterase was evaluated using enzymatic fluorometric and enzymatic colorimetric assays, respectively. An enzyme kinetic study using Michaelis-Menten and the derived Lineweaver-Burk plot was performed to understand the possible types of inhibition. The formation of cholesterol micelles was determined using the cholesterol assay kit. The bile acid binding was measured using the colorimetric assay. The NBD cholesterol uptake in Caco-2 cells was determined using fluorometric assay. The mRNA expression of cholesterol transporter (Niemann-Pick C1-like 1) was determined by RT-PCR.

RESULTS

The results showed that C3R was a mixed-type competitive inhibitor of pancreatic lipase with the IC₅₀ value of 59.4 ± 1.41 μM. Furthermore, C3R (0.125-1 mM) inhibited pancreatic cholesterol esterase about 5-18%. In addition, C3R inhibited the formation of cholesterol micelles and bound to primary and secondary bile acid. In Caco-2 cells, C3R (12.5-100 μM) exhibited a significant reduction in cholesterol uptake in both free cholesterol (17-41%) and mixed micelles (20-30%). Finally, C3R (100 μM) was able to suppress mRNA expression of NPC1L1 in Caco-2 cells after 24 h incubation.

CONCLUSIONS

The present findings suggest that C3R acts as a lipid-lowering agent through inhibition of lipid digestion and absorption.

Cyanidin 3-Rutinoside, an Anthocyanin Pigment of Schisandra chinensis Baill, Inhibits Allergic Inflammation

The occurrence of allergy-mediated inflammatory diseases such as asthma and atopic dermatitis have increased, but comprehensive treatment remains difficult. Previous studies have shown that Schisandra chinensis Baill has antioxidant, antidiabetic, and antitumorigenic effects. Cyanidin 3-rutinoside (CR) is the major anthocyanin pigment of S. chinensis. However, the biological effects of CR have been rarely studied to date. Therefore, the aim of this study was to investigate the regulatory effects of CR on phorbol-12-myristate-13-acetate (PMA)/A23187-induced allergic inflammation in vitro. CR inhibited the secretion of inflammatory cytokines such as interleukin-6 and tumor necrosis factor-α, and it also suppressed the phosphorylation of nuclear factor-kappa B. These results show that CR ameliorated PMA/A23187-induced allergic inflammation via the suppression of inflammatory cytokines in HMC-1 cells. Therefore, CR has potential as a therapeutic agent for allergic diseases.

Mulberry Extract Attenuates Endothelial Dysfunction through the Regulation of Uncoupling Endothelial Nitric Oxide Synthase in High Fat Diet Rats

Dyslipidemia is associated with endothelial dysfunction, which is linked to nitric oxide (NO) biology. The coupling of endothelial NO synthase with cofactors is a major step for NO release. This study is aimed to investigate the vascular pharmacology effects of mulberry in rat thoracic aorta and human vascular endothelial cells. In vitro, we investigated the protective effects of the mulberry extract and its main component cyanidin-3-rutinoside (C-3-R), against oxidized low-density lipoprotein (ox-LDL)-induced endothelial nitric oxide synthase (eNOS) uncoupling. Whereas ox-LDL significantly decreased NO levels in endothelial cells, mulberry extract, and C-3-R significantly recovered NO levels and phospho-eNOS Thr495 and Ser1177 expression. In vivo, mulberry was administered to 60% of high-fat diet (w/w)-fed Sprague Dawley (SD) rats for six weeks, in which endothelium-dependent relaxations were significantly improved in organ bath studies and isometric tension recordings. Consistently, aortic expressions of phospho-eNOS and nitrotyrosine were increased. Mulberry also raised serum NO levels, increased phosphorylation of eNOS, and reduced nitrotyrosine and intracellular reactive oxygen species (ROS) in aortas, showing that mulberry preserves endothelium-dependent relaxation in aortas from high-fat diet rats. We suggest that this effect is mediated through enhanced NO bioavailability, in which the regulation of ROS and its reduced eNOS uncoupling are involved.