Increasing Doses of Blueberry Polyphenols Alters Colonic Metabolism and Calcium Absorption in Ovariectomized Rats

The Preventive Impact of Chokeberry (Aronia melanocarpa L.) Extract Regarding the Disruption of Calcium and Phosphorus Homeostasis and Chosen Pathways of Its Regulation in an Animal Model of General Population Exposure to Cadmium

Background: Our previous research in an experimental model of current environmental human exposure to cadmium (Cd) (female rats fed a diet containing Cd at 1 and 5 mg/kg for up to 2 years) revealed that chronic treatment with this toxic element destroyed the metabolism of the bone tissue, decreased mineralisation, and weakened bone biomechanical properties, whereas the co-administration of a 0.1% chokeberry (Aronia melanocarpa L. (Michx.) Elliott berry) extract (AME) ameliorated the osteotoxic action of Cd. Methods: In this study, it was explored whether the unfavourable effect of Cd and the protective action of AME might be mediated by the impact on the metabolism of bone essential elements such as calcium (Ca) and inorganic phosphorus (Pi), including the pathways of its regulation by calciotropic hormones (parathormone-PTH, calcitonin-CT, and 1,25-dihydroxyvitamin D3-1,25(OH)2D3) and Klotho. Results: Low-level Cd treatment (1 mg/kg) caused only a temporary elevation in the serum PTH concentration and a decline in the concentration of CT. Moderate treatment with Cd (5 mg/kg) destroyed the body homeostasis of both mineral elements (lowered their concentrations in the serum and enhanced urinary loss), influenced the serum concentrations of Klotho and calciotropic hormones, as well as reduced the concentrations of 25-hydroxyvitamin D 1alpha-hydroxylase (1alpha-OHase) and 1,25(OH)2D3 in the kidney. The application of AME during Cd intoxication improved the pathways involved in maintaining Ca and Pi homeostasis and allowed subjects to maintain the proper levels of these elements in the serum and urine. Conclusions: In conclusion, Cd at low-to-moderate exposure may exert an unfavourable impact on bone by influencing the pathways involved in regulating Ca and Pi metabolism and destroying the body status of these minerals. It seems that the possible mechanism of the osteoprotective effect of AME during chronic intoxication with this toxic element involves normalization of the concentrations of calciotropic hormones and Klotho in the serum and improvement of the homeostasis of Ca and Pi. This study provided further evidence that chokeberry products may be an effective strategy in counteracting the unfavourable effects of chronic low-to-moderate exposure to Cd.

The mechanism of pectin in improving anthocyanin stability and the application progress of their complexes: A review

Improving anthocyanin stability is a major challenge for the food industry. Studies have revealed that the interaction with pectin through non-covalent bonds can improve the anthocyanin stability, thus showing the potential to alleviate the above challenges. However, the interactions are highly complex and diverse. Thus, analyzing the effect of this interaction on anthocyanin stability is essential to promote anthocyanin-pectin complexes application in functional foods. Pectin can interact with anthocyanins through covalent and non-covalent interactions, and these interactions are affected by their structure, the external environment, and the processing methods. Through their interaction with pectin, the thermal, color, and storage stability of anthocyanins are improved, enhancing their bioavailability in the gastrointestinal and facilitating their application range in food processing. This review provides a theoretical reference for improving anthocyanin stability and increasing the application range of anthocyanin-pectin complexes.

Blueberry (Vaccinium spp.) Anthocyanins and Their Functions, Stability, Bioavailability, and Applications

Blueberry fruits are rich in anthocyanins. There are 25 known anthocyanidins found in blueberries (Vaccinium spp.) until now. Anthocyanins found in blueberries have attracted considerable interest for their outstanding abilities as antioxidants, anti-inflammatory agents, anti-diabetic, anti-obesity, and neuroprotection compounds, as well as their potential for preventing cardiovascular diseases, protecting vision, and inhibiting cancer development. However, their application is constrained by issues related to instability and relatively low bioavailability. Thus, this review provides a detailed overview of categories, functions, stability, and bioavailability of blueberry anthocyanins and their practical applications. The available studies indicate that there is more potential for the industrial production of blueberry anthocyanins.

Screening of Mpro Protease (SARS-CoV-2) Covalent Inhibitors from an Anthocyanin-Rich Blueberry Extract Using an HRMS-Based Analytical Platform

BACKGROUND

The viral main protease (Mpro) of SARS-CoV-2 has been recently proposed as a key target to inhibit virus replication in the host. Therefore, molecules that can bind the catalytic site of Mpro could be considered as potential drug candidates in the treatment of SARS-CoV-2 infections. Here we proposed the application of a state-of-the-art analytical platform which combines metabolomics and protein structure analysis to fish-out potential active compounds deriving from a natural matrix, i.e., a blueberry extract.

METHODS

The experiments focus on finding MS covalent inhibitors of Mpro that contain in their structure a catechol/pyrogallol moiety capable of binding to the nucleophilic amino acids of the enzyme's catalytic site.

RESULTS

Among the potential candidates identified, the delphinidin-3-glucoside showed the most promising results. Its antiviral activity has been confirmed in vitro on Vero E6 cells infected with SARS-CoV-2, showing a dose-dependent inhibitory effect almost comparable to the known Mpro inhibitor baicalin. The interaction of delphinidin-3-glucoside with the Mpro pocket observed was also evaluated by computational studies.

CONCLUSIONS

The HRMS analytical platform described proved to be effective in identifying compounds that covalently bind Mpro and are active in the inhibition of SARS-CoV-2 replication, such as delphinidin-3-glucoside.

Unlocking the health potential of anthocyanins: a structural insight into their varied biological effects

Anthocyanins have become increasingly important to the food industry due to their colorant features and many health-promoting activities. Numerous studies have linked anthocyanins to antioxidant, anti-inflammatory, anticarcinogenic properties, as well as protection against heart disease, certain types of cancer, and a reduced risk of diabetes and cognitive disorders. Anthocyanins from various foods may exhibit distinct biological and health-promoting activities owing to their structural diversity. In this review, we have collected and tabulated the key information from various recent published studies focusing on investigating the chemical structure effect of anthocyanins on their stability, antioxidant activities, in vivo fate, and changes in the gut microbiome. This information should be valuable in comprehending the connection between the molecular structure and biological function of anthocyanins, with the potential to enhance their application as both colorants and functional compounds in the food industry.

Protective effects of blueberries on vascular function: A narrative review of preclinical and clinical evidence

Blueberries are rich in nutrients and (poly)phenols, popular with consumers, and a major agricultural crop with year-round availability supporting their use in food-based strategies to promote human health. Accumulating evidence indicates blueberry consumption has protective effects on cardiovascular health including vascular dysfunction (i.e., endothelial dysfunction and arterial stiffening). This narrative review synthesizes evidence on blueberries and vascular function and provides insight into underlying mechanisms with a focus on oxidative stress, inflammation, and gut microbiota. Evidence from animal studies supports beneficial impacts on vascular function. Human studies indicate acute and chronic blueberry consumption can improve endothelial function in healthy and at-risk populations and may modulate arterial stiffness, but that evidence is less certain. Results from cell, animal, and human studies suggest blueberry consumption improves vascular function through improving nitric oxide bioavailability, oxidative stress, and inflammation. Limited data in animals suggest the gut microbiome mediates beneficial effects of blueberries on vascular function; however, there is a paucity of studies evaluating the gut microbiome in humans. Translational evidence indicates anthocyanin metabolites mediate effects of blueberries on endothelial function, though this does not exclude potential synergistic and/or additive effects of other blueberry components. Further research is needed to establish the clinical efficacy of blueberries to improve vascular function in diverse human populations in a manner that provides mechanistic information. Translation of clinical research to the community/public should consider feasibility, social determinants of health, culture, community needs, assets, and desires, barriers, and drivers to consumption, among other factors to establish real-world impacts of blueberry consumption.

Effect of red wheat, aleurone, and testa layers on colon cancer biomarkers, nitrosative stress, and gut microbiome composition in rats

We previously found greater reduction of colon cancer (CC) biomarkers for red wheat compared to white wheat regardless of refinement state. In the present study we examined whether the phenolic-rich aleurone and testa layers are drivers of chemoprevention by red wheat and their influence on gut microbiota composition using a 1,2-dimethylhydrazine-induced CC rat model. Rats were fed a low-fat diet (16% of energy as fat), high-fat diet (50% of energy as fat), or high-fat diet containing whole red wheat, refined red wheat, refined white wheat, or aleurone- or testa-enriched fractions for 12 weeks. Morphological markers (aberrant crypt foci, ACF) were assessed after methylene blue staining and biochemical markers (3-nitrotyrosine [3-NT], Dclk1) by immunohistochemical determination of staining positivity within aberrant crypts. Gut microbiota composition was evaluated from 16S rRNA gene sequencing of DNA extracted from cecal contents. Relative to the high-fat diet, the whole and refined red wheat, refined white wheat, and testa-enriched fraction decreased ACF, while only the refined red wheat and aleurone-enriched fraction decreased 3-NT. No significant differences were observed for Dclk1. An increase in microbial diversity was observed for the aleurone-enriched fraction (ACE index) and whole red wheat (Inverse Simpson Index). The diet groups significantly modified overall microbiome composition, including altered abundances of Lactobacillus, Mucispirillum, Phascolarctobacterium, and Blautia coccoides. These results suggest that red wheat may reduce CC risk through modifications to the gut microbiota and nitrosative stress, which may be due, in part, to the influence of dietary fiber and the phenolic-rich aleurone layer.

Mechanistic Insights into Effects of Different Dietary Polyphenol Supplements on Arsenic Bioavailability, Biotransformation, and Toxicity Based on a Mouse Model

Arsenic (As) exposure has been related to many diseases, including cancers. Given the antioxidant and anti-inflammatory properties, the dietary supplementation of polyphenols may alleviate As toxicity. Based on a mouse bioassay, this study investigated the effects of chlorogenic acid (CA), quercetin (QC), tannic acid (TA), resveratrol (Res), and epigallocatechin gallate (EGCG) on As bioavailability, biotransformation, and toxicity. Intake of CA, QC, and EGCG significantly (p < 0.05) increased total As concentrations in liver (0.48-0.58 vs 0.27 mg kg-1) and kidneys (0.72-0.93 vs 0.59 mg kg-1) compared to control mice. Upregulated intestinal expression of phosphate transporters with QC and EGCG and proliferation of Lactobacillus in the gut of mice treated with CA and QC were observed, facilitating iAsV absorption via phosphate transporters and intestinal As solubility via organic acid metabolites. Although As bioavailability was elevated, serum levels of alpha fetoprotein and carcinoembryonic antigen of mice treated with all five polyphenols were reduced by 13.1-16.1% and 9.83-17.5%, suggesting reduced cancer risk. This was mainly due to higher DMAV (52.1-67.6% vs 31.4%) and lower iAsV contribution (4.95-10.7% vs 27.9%) in liver of mice treated with polyphenols. This study helps us develop dietary strategies to lower As toxicity.

Urinary and Daily Assumption of Polyphenols and Hip-Fracture Risk: Results from the InCHIANTI Study

A high polyphenol intake has been associated with higher bone-mineral density. In contrast, we recently demonstrated that the urinary levels of these micronutrients were associated with the long-term accelerated deterioration of the bone. To expand on the health consequences of these findings, we assessed the association between urinary level and dietary intake of polyphenols and the 9-year risk of hip fractures in the InCHIANTI study cohort. The InCHIANTI study enrolled representative samples from two towns in Tuscany, Italy. Baseline data were collected in 1998 and at follow-up visits in 2001, 2004, and 2007. Of the 1453 participants enrolled at baseline, we included 817 participants in this study who were 65 years or older at baseline, donated a 24 hour urine sample, and underwent a quantitative computerized tomography (pQCT) of the tibia. Fracture events were ascertained by self-report over 9 years of follow-up. Thirty-six hip fractures were reported over the 9-year follow-up. The participants who developed a hip fracture were slightly older, more frequently women, had a higher dietary intake of polyphenols, had higher 24-hour urinary polyphenols excretion, and had a lower fat area, muscle density, and cortical volumetric Bone Mineral Density (vBMD) in the pQCT of the tibia. In logistic regression analyses, the baseline urinary excretion of total polyphenols, expressed in mg as a gallic acid equivalent, was associated with a higher risk of developing a hip fracture. Dietary intake of polyphenols was not associated with a differential risk of fracture. In light of our findings, the recommendation of an increase in dietary polyphenols for osteoporosis prevention should be considered with caution.

The contribution of regulated colonic calcium absorption to the maintenance of calcium homeostasis

Calcium absorption and secretion can occur along the length of the small and large intestine. To date, the focus of research into intestinal calcium absorption has been the small intestine, the site contributing the majority of intestinal calcium absorption. However, evidence that the colon contributes as much as 10% of enteral calcium transport has been available for decades. Transcellular calcium absorption and bidirectional paracellular calcium flux contributing to either net absorption or secretion have been observed in the colon, depending on the physiological state. Moreover, the calcium transport pathways contributing to colonic absorption or secretion are regulated by a variety of hormones, including calcitriol, plasma calcium and dietary factors, including prebiotics. Herein we review historical and recent research highlighting the role of colonic calcium transport in overall maintenance of calcium balance, and suggest these data are consistent with the colon being a site of significant regulated transepithelial calcium transport.

The Impact of Hempseed Consumption on Bone Parameters and Body Composition in Growing Female C57BL/6 Mice

Optimizing peak bone mass is critical to healthy aging. Beyond the established roles of dietary minerals and protein on bone integrity, fatty acids and polyphenols modify bone structure. This study investigated the effect of a diet containing hempseeds (HS), which are rich in polyunsaturated fatty acids and polyphenols, on bone mineral density, bone cell populations and body composition. Groups (n = 8 each) of female C57BL/6 mice were fed one of three diets (15% HS by weight; 5% HS; 0% HS (control)) from age 5 to 30 weeks. In vivo whole-body composition and bone mineral density and content were measured every 4 weeks using dual-energy X-ray absorptiometry. Ex vivo humeri cell populations in the epiphyseal plate region were determined by sectioning the bone longitudinally, mounting the sections on slides and staining with tartrate-resistant acid phosphatase and alkaline phosphatase stain to identify osteoclasts and osteoblasts, respectively. Mixed models with repeated measures across experimental weeks showed that neither body weight nor body weight gain across weeks differed among groups yet mice fed the 15% HS diet consumed significantly more food and more kilocalories per g body weight gained than those fed the 5% HS and control diets (p < 0.0001). Across weeks, fat mass was significantly higher in the 5% HS versus the control group (p = 0.02). At the end point, whole-body bone mineral content was significantly higher in the control compared to the 5% HS group (p = 0.02). Humeri from both HS groups displayed significantly lower osteoblast densities compared to the control group (p < 0.0001). No relationship was seen between osteoblast density and body composition measurements. These data invite closer examination of bone cell activity and microarchitecture to determine the effect of habitual HS consumption on bone integrity.

Blueberry Polyphenols do not Improve Bone Mineral Density or Mechanical Properties in Ovariectomized Rats

Osteoporosis-related bone fragility fractures are a major public health concern. Given the potential for adverse side effects of pharmacological treatment, many have sought alternative treatments, including dietary changes. Based on recent evidence that polyphenol-rich foods, like blueberries, increase calcium absorption and bone mineral density (BMD), we hypothesized that blueberry polyphenols would improve bone biomechanical properties. To test this, 5-month-old ovariectomized Sprague-Dawley rats (n = 10/gp) were orally gavaged for 90 days with either a purified extract of blueberry polyphenols (0-1000 mg total polyphenols/kg bw/day) or lyophilized blueberries (50 mg total polyphenols/kg bw/day). Upon completion of the dosing regimen, right femur, right tibia, and L1-L4 vertebrae were harvested and assessed for bone mineral density (BMD), with femurs being further analyzed for biomechanical properties via three-point bending. There were no differences in BMD at any of the sites analyzed. For bone mechanical properties, the only statistically significant difference was the high dose group having greater ultimate stress than the medium dose, although in the absence of differences in other measures of bone mechanical properties, we concluded that this result, while statistically significant, had little biological significance. Our results indicate that blueberry polyphenols had little impact on BMD or bone mechanical properties in an animal model of estrogen deficiency-induced bone loss.

Anti-Osteoporotic Mechanisms of Polyphenols Elucidated Based on In Vivo Studies Using Ovariectomized Animals

Polyphenols are widely known for their antioxidant activity, i.e., they have the ability to suppress oxidative stress, and this behavior is mediated by the autoxidation of their phenolic hydroxyl groups. Postmenopausal osteoporosis is a common health problem that is associated with estrogen deficiency. Since oxidative stress is thought to play a key role in the onset and progression of osteoporosis, it is expected that polyphenols can serve as a safe and suitable treatment in this regard. Therefore, in this review, we aimed to elucidate the anti-osteoporotic mechanisms of polyphenols reported by in vivo studies involving the use of ovariectomized animals. We categorized the polyphenols as resveratrol, purified polyphenols other than resveratrol, or polyphenol-rich substances or extracts. Literature data indicated that resveratrol activates sirtuin 1, and thereafter, suppresses osteoclastogenic pathways, such as the receptor activator of the nuclear factor kappa B (RANK) ligand (RANKL) pathway, and promotes osteoblastogenic pathways, such as the wingless-related MMTV integration site pathway. Further, we noted that purified polyphenols and polyphenol-rich substances or extracts exert anti-inflammatory and/or antioxidative effects, which inhibit RANKL/RANK binding via the NF-κB pathway, resulting in the suppression of osteoclastogenesis. In conclusion, antioxidative and anti-inflammatory polyphenols, including resveratrol, can be safe and effective for the treatment of postmenopausal osteoporosis based on their ability to regulate the imbalance between bone formation and resorption.

Effects of Concord grape juice flavor intensity and phenolic compound content on glycemia, appetite and cognitive function in adults with excess body weight: a randomized double-blind crossover trial

Background & aims: Concord grape (Vitis lambrusca) juice (CGJ) contains a unique combination of polyphenolic compounds with diverse effects on human health. It also has an intense sensory profile that may modify food choice. Daily consumption of CGJ over 8 weeks reduced fasting blood glucose. However, the impact on 24h-postprandial glucose response from CGJ is still not clear. The purpose of this study was to assess the effect of CGJ flavor intensity and phenolic content on 24 h postprandial glucose concentrations, appetitive sensations, and cognitive function in adults with excess body weight when consumed alone or with a meal. Methods: In a randomized, double-blind, crossover design study, participants consumed three types of beverages: 100% CGJ, a polyphenol-free grape flavored drink with the same flavor essence (LP) or a polyphenol-free grape flavored drink with reduced flavor essence (LPF) either without (trial I) or with (trial II) a meal. 24 h glucose was measured through continuous glucose monitoring. Phenolic metabolite excretion was assessed in 24 h urine samples. Appetite (hunger, thirst, fullness, desire to eat, and prospective consumption) and cognitive function (alertness, energetic, strength, calmness, and relaxation) were assessed hourly through visual analog scales. Results: Thirty-four adults completed trial I and 34 adults completed trial II. When consumed with a meal, beverages with customary flavor essence (CGJ and LP) reduced hunger, desire to eat, and prospective consumption and consumption of the polyphenol-free reduced flavor essence beverage was associated with higher 24 h glucose _tAUC. No consistent effects were observed for cognitive outcomes. When consumed alone, CGJ was related to lower glycemic responses by those excreting a higher concentration of the phenolic metabolite iso/ferulic-3'-O-glucuronide, but in beverages without CG phenolics and reduced flavor essence, glycemia was higher among those excreting higher concentrations of caffeic acid-O-sulfate. Conclusions: Both natural phenolics and flavor essence of CGJ may help to moderate appetite and glycemia. Clinical Trials registered at http://www.clinicaltrials.gov: NCT03409484 (trial I) and NCT03409497 (trial II).

Hypoglycemic and hypolipidemic effects of blueberry anthocyanins by AMPK activation: In vitro and in vivo studies

Blueberries are rich in bioactive anthocyanins, with a high level of malvidin, which is associated with antioxidant benefits that contribute to reducing the risk of diabetes. The objective of this study was to investigate the hypoglycemic and hypolipidemic effects of blueberry anthocyanin extract (BAE), malvidin (Mv), malvidin-3-glucoside (Mv-3-glc), and malvidin-3-galactoside (Mv-3-gal) in both human hepatocarcinoma cell line HepG2 and in a high-fat diet combining streptozotocin-induced diabetic mice. High glucose treatment significantly increased hepatic oxidative stress up to 6-fold and decreased HepG2 cell viability. Pretreatment with BAE, Mv, Mv-3-glc and Mlv-3-gal significantly mitigated these damages by lowering the reactive oxygen species (ROS) by 87, 80, 76, and 91%, and increasing cell viability by 88, 79, 73, and 98%, respectively. These pretreatments also effectively inhibited hyperglycemia and hyperlipidemia, respectively by reducing the expression levels of enzymes participating in gluconeogenesis and lipogenesis and enhancing those involved in glycogenolysis and lipolysis, via adenosine monophosphate-activated protein kinase (AMPK) signaling pathway in HepG2 cells. To determinate the role of AMPK in BAE-induced reaction of glucose and lipid metabolism in vivo, doses of 100 mg/kg (blueberry anthocyanin extracts – low concentration, BAE-L) and 400 mg/kg (blueberry anthocyanin extracts – high concentration, BAE-H) were administrated per day to diabetic mice for 5 weeks. BAE treatments had a significant (P < 0.05) effect on body weight and increased the AMPK activity, achieving the decrease of blood- and urine-glucose, as well as triglyceride and total cholesterol. This research suggested that anthocyanins contributed to the blueberry extract-induced hypoglycemia and hypolipidemia effects in diabetes and BAE could be a promising functional food or medicine for diabetes treatment.

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BAE showed hypoglycemic effect on HepG2 and STZ-induced diabetic mice.

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BAE exhibited hypolipidemic effect on HepG2 and STZ-induced diabetic mice.

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BAE inhibited PEPCK and G6Pase expression.

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BAE activated AMPK and decreased the expressions of PGC-1α and FOXO1.

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BAE could be a potential functional food or nutraceutical for diabetes treatment.

Blueberry polyphenols alter gut microbiota & phenolic metabolism in rats

Consuming polyphenol-rich fruits and vegetables, including blueberries, is associated with beneficial health outcomes. Interest in enhancing polyphenol intakes via dietary supplements has grown, though differences in fruit versus supplement matrix on gut microbiota and ultimate phenolic metabolism to bioactive metabolites are unknown. To evaluate this, 5-month-old, ovariectomized, Sprague-Dawley rats were gavaged for 90 d with a purified extract of blueberry polyphenols (0, 50, 250, or 1000 mg total polyphenols per kg bw per d) or lyophilized blueberries (50 mg total polyphenols per kg bw per d, equivalent to 150 g fresh blueberries per day in humans). Urine, feces, and tissues were assessed for gut microbiota and phenolic metabolism. Significant dose- and food matrix-dependent effects were observed at all endpoints measured. Gut microbial populations showed increased diversity at moderate doses but decreased diversity at high doses. Urinary phenolic metabolites were primarily observed as microbially derived metabolites and underwent extensive host xenobiotic phase II metabolism. Thus, blueberry polyphenols in fruit and supplements induce differences in gut microbial communities and phenolic metabolism, which may alter intended health effects.