Anthocyanins: A Comprehensive Review of Their Chemical Properties and Health Effects on Cardiovascular and Neurodegenerative Diseases

VvMYB15 and VvWRKY40 Positively Co-regulated Anthocyanin Biosynthesis in Grape Berries in Response to Root Restriction

In most grapevine planting regions, especially in south of China, plenty of rainfall and high water level underground are the characteristic of the area, a series of problem during fruit ripening easily caused poor color quality. Thereby affecting fruit quality, yield and economic benefits. The accumulation of anthocyanin is regulated by transcriptional regulatory factor and a series of cultivation measures, root restriction can make plants in the environment of stress and stress relief, root restriction induced the higher expression of VvMYB15 and VvWRKY40, and consistent with anthocyanin accumulation. Whether and how root restriction-inducible VvMYB15 and VvWRKY40 transcription factor regulate anthocyanin synthesis in grape berry is still unclear. In this study, we identified that the transient overexpression of VvMYB15 and VvWRKY40 alone or both in strawberry fruits and grape berries can promote anthocyanin accumulation and increase the expression level of anthocyanin biosynthetic genes, indicating VvMYB15 and VvWRKY40 play a positive regulator of anthocyanin biosynthesis. Furthermore, we confirmed that both VvMYB15 and VvWRKY40 specifically bind to the promoter region of VvF3'5'H and VvUFGT, and the expression of VvF3'5'H and VvUFGT is further activated through the heterodimer formation between VvMYB15 and VvWRKY40. Finally, we confirmed that VvMYB15 promoted anthocyanin accumulation by interacting with VvWRKY40 in grape berries, our findings provide insights into a mechanism involving the synergistic regulation of root restriction-dependent coloration and biosynthesis via a VvMYB15 and VvWRKY40 alone or both in grape berries.

Nanoencapsulation-Based Edible Coating of Essential Oils as a Novel Green Strategy Against Fungal Spoilage, Mycotoxin Contamination, and Quality Deterioration of Stored Fruits: An Overview

Currently, applications of essential oils for protection of postharvest fruits against fungal infestation and mycotoxin contamination are of immense interest and research hot spot in view of their natural origin and possibly being an alternative to hazardous synthetic preservatives. However, the practical applications of essential oils in broad-scale industrial sectors have some limitations due to their volatility, less solubility, hydrophobic nature, and easy oxidation in environmental conditions. Implementation of nanotechnology for efficient incorporation of essential oils into polymeric matrices is an emerging and novel strategy to extend its applicability by controlled release and to overcome its major limitations. Moreover, different nano-engineered structures (nanoemulsion, suspension, colloidal dispersion, and nanoparticles) developed by applying a variety of nanoencapsulation processes improved essential oil efficacy along with targeted delivery, maintaining the characteristics of food ingredients. Nanoemulsion-based edible coating of essential oils in fruits poses an innovative green alternative against fungal infestation and mycotoxin contamination. Encapsulation-based coating of essential oils also improves antifungal, antimycotoxigenic, and antioxidant properties, a prerequisite for long-term enhancement of fruit shelf life. Furthermore, emulsion-based coating of essential oil is also efficient in the protection of physicochemical characteristics, viz., firmness, titrable acidity, pH, weight loss, respiration rate, and total phenolic contents, along with maintenance of organoleptic attributes and nutritional qualities of stored fruits. Based on this scenario, the present article deals with the advancement in nanoencapsulation-based edible coating of essential oil with efficient utilization as a novel safe green preservative and develops a green insight into sustainable protection of fruits against fungal- and mycotoxin-mediated quality deterioration.

High-Pressure Processing vs. Thermal Treatment: Effect on the Stability of Polyphenols in Strawberry and Apple Products

Polyphenols are important bioactive compounds that are affected by processing. The consumer's demand for minimally processed products contributes to the increase in non-thermal technologies such as high-pressure processing (HPP) in the food industry. This review is aimed at critically discussing the positive and negative effects of thermal treatment (TT) and HPP on the stability of different polyphenol families in agro-food products obtained from strawberry and apple, two of the most used fruits in food processing. Our findings show that the phenolic content was affected by processing, fruit type, polyphenol family, and storage conditions (time and temperature) of the final product. To increase shelf life, manufacturers aiming to preserve the natural content of polyphenols need to find the sweet spot between polyphenol stability and product shelf-life since the residual enzyme activity from HPP can affect polyphenols negatively.

Advanced approaches for improving bioavailability and controlled release of anthocyanins

Anthocyanins are a group of phytochemicals responsible for the purple or red color of plants. Additionally, they are recognized to have health promoting functions including anti-cardiovascular, anti-thrombotic, anti-diabetic, antimicrobial, neuroprotective, and visual protective effect as well as anti-cancer activities. Thus, consumption of anthocyanin supplement or anthocyanin-rich foods has been recommended to prevent the risk of development of chronic diseases. However, the low stability and bioavailability of anthocyanins limit the efficacy and distribution of anthocyanins in human body. Thus, strategies to achieve target site-local delivery with good bioavailability and controlled release rate are necessary. This review introduced and discussed the latest advanced techniques of designing lipid-based, polysaccharide-based and protein-based complexes, nano-encapsulation and exosome to overcome the limitation of anthocyanins. The improved bioavailability and controlled release of anthocyanins have great significance for gastrointestinal tract absorption, transepithelial transportation and cellular uptake. The techniques of applying different biocompatible materials and modifying the solubility of anthocyanins complex could achieve target site-local delivery with negligible degradation and good bioavailability in human body.

Dietary Antioxidant Anthocyanins Mitigate Type II Diabetes through Improving the Disorder of Glycometabolism and Insulin Resistance

Insulin resistance (IR) is one of the pathological reasons for type II diabetes mellitus (T2DM). Therefore, it is important to prevent the body from developing T2DM by improving IR and maintaining glucose homeostasis. Anthocyanins (ACNs) are water-soluble pigments and are widely distributed in natural products. This article summarizes research on the bioavailability and metabolism of ACNs. Moreover, we further elaborate on how ACNs reduce IR and hyperglycemia during the development of T2DM based on studies over the past 20 years. Many studies have demonstrated that ACNs are small molecules that target the pancreatic, liver, muscle, and adipose tissues, preventing IR and hyperglycemia. However, the molecular mechanisms are still unclear. Therefore, we envision whether the molecular mechanism of reducing T2DM by ACNs could be more deeply investigated.

Anthocyanins: From Mechanisms of Regulation in Plants to Health Benefits in Foods

Anthocyanins represent the major red, purple, and blue pigments in many flowers, fruits, vegetables, and cereals. They are also recognized as important health-promoting components in the human diet with protective effects against many chronic diseases, including cardiovascular diseases, obesity, and cancer. Anthocyanin biosynthesis has been studied extensively, and both biosynthetic and key regulatory genes have been isolated in many plant species. Here, we will provide an overview of recent progress in understanding the anthocyanin biosynthetic pathway in plants, focusing on the transcription factors controlling activation or repression of anthocyanin accumulation in cereals and fruits of different plant species, with special emphasis on the differences in molecular mechanisms between monocot and dicot plants. Recently, new insight into the transcriptional regulation of the anthocyanin biosynthesis, including positive and negative feedback control as well as epigenetic and post-translational regulation of MYB-bHLH-WD40 complexes, has been gained. We will consider how knowledge of regulatory mechanisms has helped to produce anthocyanin-enriched foods through conventional breeding and metabolic engineering. Additionally, we will briefly discuss the biological activities of anthocyanins as components of the human diet and recent findings demonstrating the important health benefits of anthocyanin-rich foods against chronic diseases.

Impact of Simulated Gastrointestinal Conditions on Antiglycoxidant and α-Glucosidase Inhibition Capacities of Cyanidin-3-O-Glucoside

Cyanidin-3-O-glucoside (C3G) is a widespread anthocyanin derivative, which has been reported in vitro to exert potent antioxidant, antiglycation and α-glucosidase inhibition effects. Nevertheless, the physiological relevance of such properties remains uncertain considering its significant instability in gastrointestinal conditions. A simulated digestion procedure was thus instigated to assess the influence of gastric and intestinal media on its chemical integrity and biological activities. HPLC analyses of digested C3G samples confirmed the striking impact of intestinal conditions, as attested by a decomposition ratio of 70%. In contrast, with recovery rates of around 90%, antiglycation, as well as DPPH and ABTS scavenging assays, uniformly revealed a noteworthy persistence of its antiglycoxidant capacities. Remarkably, a prominent increase of its α-glucosidase inhibition activity was even observed after the intestinal phase, suggesting that classical in vitro evaluations might underestimate C3G antidiabetic potential. Consequently, the present data provide novel and specific insights on C3G’s digestive fate, suggesting that the gastrointestinal tract does not profoundly affect its positive action on oxidative and carbonyl stresses. More specifically, it also tends to support its regulating effects on postprandial hyperglycemia and its potential usefulness for diabetes management.

Anthocyanin Extract from Purple Sweet Potato Exacerbate Mitophagy to Ameliorate Pyroptosis in Klebsiella pneumoniae Infection

Given the rise of morbidity and mortality caused by Klebsiella pneumoniae (KP), the increasing number of strains resistant to antibiotics, and the emergence of hypervirulent Klebsiella pneumonia, treatment of KP infection becomes difficult; thus, novel drugs are necessary for treatment. Anthocyanins, or natural flavonoids, have an extensive effect against bacterial infection. However, few studies on anti-KP are identified. Here, we evaluated the therapeutic effect of purple sweet potato anthocyanins (PSPAs) on KP, containing 98.7% delphinidin 3-sambubioside. Results showed that KP-infected mice after PSPAs treatment manifested decreased mortality, weakened lung injury, dampened inflammatory responses, and reduced bacterial systemic dissemination in vivo. In Vitro, PSPAs significantly suppressed pyroptosis and restricted NLRP3 inflammasome activation in alveolar macrophages infected with KP. As for the mechanism, PSPAs promote mitophagy by recruiting Parkin to the mitochondria. PSPAs-conferred mitophagy increased mitochondrial membrane potential and decreased mitochondrial reactive oxygen species and mitochondrial DNA, resulting in impaired NLRP3 inflammasome activation. In addition, the promotion of mitophagy by PSPAs required the Nrf2 signaling pathway. Collectively, these findings suggest that PSPAs are a potential option for the treatment of KP infection.

Light Induced Regulation Pathway of Anthocyanin Biosynthesis in Plants

Anthocyanins are natural pigments with antioxidant effects that exist in various fruits and vegetables. The accumulation of anthocyanins is induced by environmental signals and regulated by transcription factors in plants. Numerous evidence has indicated that among the environmental factors, light is one of the most signal regulatory factors involved in the anthocyanin biosynthesis pathway. However, the signal transduction of light and molecular regulation of anthocyanin synthesis remains to be explored. Here, we focus on the research progress of signal transduction factors for positive and negative regulation in light-dependent and light-independent anthocyanin biosynthesis. In particular, we will discuss light-induced regulatory pathways and related specific regulators of anthocyanin biosynthesis in plants. In addition, an integrated regulatory network of anthocyanin biosynthesis controlled by transcription factors is discussed based on the significant progress.

Polyphenols and neuroprotection: Therapeutic implications for cognitive decline

Dietary polyphenols have been the focus of major interest for their potential benefits on human health. Several preclinical studies have been conducted to provide a rationale for their potential use as therapeutic agents in preventing or ameliorating cognitive decline. However, results from human studies are scarce and poorly documented. The aim of this review was to discuss the potential mechanisms involved in age-related cognitive decline or early stage cognitive impairment and current evidence from clinical human studies conducted on polyphenols and the aforementioned outcomes. The evidence published so far is encouraging but contrasting findings are to be taken into account. Most studies on anthocyanins showed a consistent positive effect on various cognitive aspects related to aging or early stages of cognitive impairment. Studies on cocoa flavanols, resveratrol, and isoflavones provided substantial contrasting results and further research is needed to clarify the therapeutic potential of these compounds. Results from other studies on quercetin, green tea flavanols, hydroxycinnamic acids (such as chlorogenic acid), curcumin, and olive oil tyrosol and derivatives are rather promising but still too few to provide any real conclusions. Future translational studies are needed to address issues related to dosage, optimal formulations to improve bioavailability, as well as better control for the overall diet, and correct target population.

Beyond Purple Tomatoes: Combined Strategies Targeting Anthocyanins to Generate Crimson, Magenta, and Indigo Fruit

The range of colours of many flowers and fruits is largely due to variations in the types of anthocyanins produced. The degree of hydroxylation on the B-ring affects the hue of these pigments, causing a shift from the orange end of the visible spectrum to the blue end. Besides colour, this modification can also affect other properties of anthocyanins, including the ability to protect the plant against different stresses or, when included in the human diet, to provide benefits for disease prevention. The level of hydroxylation of the B-ring is determined by the activity of two key hydroxylases, F3′H and F3′5′H, and by the substrate preference of DFR, an enzyme acting downstream in the biosynthetic pathway. We show that, in tomato, a strategy based on fruit-specific engineering of three regulatory genes (AmDel, AmRos1, AtMYB12) and a single biosynthetic gene (AmDFR), together with the availability of a specific mutation (f3′5′h), results in the generation of three different varieties producing high levels of anthocyanins with different levels of hydroxylation. These tomatoes show distinctive colours and mimic the classes of anthocyanins found in natural berries, thus providing unique near-isogenic material for different studies.

The effect of anthocyanins supplementation on liver enzymes among patients with metabolic disorders: A systematic review and meta-analysis of randomized clinical trials

The present study aims to summarize and quantitatively examine the available evidence on the effectiveness of anthocyanin supplementation on liver enzymes among patients with metabolic disorders, by employing a systematic review and meta-analytic approach. Online databases including PubMed/Medline, Scopus, ISI Web of Science, and Cochrane Library were searched up to June 2020 for randomized controlled trials (RCTs) that examined the effect of anthocyanin supplementation on serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) among patients with metabolic disorders. To estimate the overall effect of anthocyanin supplementation, we employed the random-effects model. In total, 12 RCTs were included in the systematic review. Pooled analysis did not show any significant changes in ALT (WMD: -0.92 U/L, 95% CI: -4.19 to 2.35, p = .58; I²  = 91.3%) and AST (WMD: -1.22 U/L, 95% CI: -3.43 to 0.99, p = .28; I²  = 87.0) concentrations after supplementation with anthocyanin. The dose and duration of supplementation were the potential sources of heterogeneity among most of the trials. However, subgroup analysis showed that the effect is not statistically significant in all subgroups. Overall, in our study, anthocyanin does not have any effect on liver enzyme levels significantly. However, future high-quality studies are still needed to confirm the results.

A Review on Chromatography-Mass Spectrometry Applications on Anthocyanin and Ellagitannin Metabolites of Blackberries and Raspberries

Berries have been widely assessed for their beneficial health effects, predominately due to their high (poly)phenol content of anthocyanins and ellagitannins. After ellagitannins and ellagic acid are metabolized by the gut microbiome, a class of compounds known as urolithins are produced, which exert potential advantageous health effects. Anthocyanins, on the other hand, undergo a complex metabolic pathway after their interaction with microbial and endogenous enzymes, forming a broad range of metabolites and catabolic products. In most cases, in vitro models and cell lines are used to generate metabolites, whereas their assessment in vivo is currently limited. Thus far, several analytical methods have been developed for the qualitative and quantitative analysis of phenolic metabolites in berries, including liquid chromatography, mass spectrometry, and other hyphenated techniques, and have been undoubtedly valuable tools for the detailed metabolite characterization and profiling. In this review, a compilation of studies providing information on the qualitative and quantitative analysis of (poly)phenol metabolites in blackberries and raspberries after the utilization of in vitro and in vivo methods is presented. The different analytical techniques employed are assessed, focusing on the fate of the produced metabolic compounds in order to provide evidence on their characteristics, formation, and beneficial effects.

Cyanidin-3-O-glucoside and its phenolic metabolites ameliorate intestinal diseases via modulating intestinal mucosal immune system: potential mechanisms and therapeutic strategies

The incidence of the intestinal disease is globally increasing, and the intestinal mucosa immune system is an important defense line. A potential environmental cause to regulate gut health is diet. Cyanidin-3-O-glucoside is a natural plant bioactive substance that has shown rising evidence of improving intestinal disease and keeping gut homeostasis. This review summarized the intestinal protective effect of Cyanidin-3-O-glucoside in vivo and in vitro and discussed the potential mechanisms by regulating the intestinal mucosal immune system. Cyanidin-3-O-glucoside and phenolic metabolites inhibited the presence and progression of intestinal diseases and explained from the aspects of repairing the intestinal wall, inhibiting inflammatory reaction, and regulating the gut microbiota. Although the animal and clinical studies are inadequate, based on the accumulated evidence, we propose that the interaction of Cyanidin-3-O-glucoside with the intestinal mucosal immune system is at the core of most mechanisms by which affect host gut diseases. This review puts forward the potential mechanism of action and targeted treatment strategies.

A Review of the Properties of Anthocyanins and Their Influence on Factors Affecting Cardiometabolic and Cognitive Health

The incidence of cardiovascular and metabolic diseases has increased over the last decades and is an important cause of death worldwide. An upcoming ingredient on the nutraceutical market are anthocyanins, a flavonoid subgroup, abundant mostly in berries and fruits. Epidemiological studies have suggested an association between anthocyanin intake and improved cardiovascular risk, type 2 diabetes and myocardial infarct. Clinical studies using anthocyanins have shown a significant decrease in inflammation markers and oxidative stress, a beneficial effect on vascular function and hyperlipidemia by decreasing low-density lipoprotein and increasing high-density lipoprotein. They have also shown a potential effect on glucose homeostasis and cognitive decline. This review summarizes the effects of anthocyanins in in-vitro, animal and human studies to give an overview of their application in medical prevention or as a dietary supplement.

Polyphenols and Their Effects on Muscle Atrophy and Muscle Health

Skeletal muscle atrophy is the decrease in muscle mass and strength caused by reduced protein synthesis/accelerated protein degradation. Various conditions, such as denervation, disuse, aging, chronic diseases, heart disease, obstructive lung disease, diabetes, renal failure, AIDS, sepsis, cancer, and steroidal medications, can cause muscle atrophy. Mechanistically, inflammation, oxidative stress, and mitochondrial dysfunction are among the major contributors to muscle atrophy, by modulating signaling pathways that regulate muscle homeostasis. To prevent muscle catabolism and enhance muscle anabolism, several natural and synthetic compounds have been investigated. Recently, polyphenols (i.e., natural phytochemicals) have received extensive attention regarding their effect on muscle atrophy because of their potent antioxidant and anti-inflammatory properties. Numerous in vitro and in vivo studies have reported polyphenols as strongly effective bioactive molecules that attenuate muscle atrophy and enhance muscle health. This review describes polyphenols as promising bioactive molecules that impede muscle atrophy induced by various proatrophic factors. The effects of each class/subclass of polyphenolic compounds regarding protection against the muscle disorders induced by various pathological/physiological factors are summarized in tabular form and discussed. Although considerable variations in antiatrophic potencies and mechanisms were observed among structurally diverse polyphenolic compounds, they are vital factors to be considered in muscle atrophy prevention strategies.

Enzymatic Metabolism of Flavonoids by Gut Microbiota and Its Impact on Gastrointestinal Cancer

Gastrointestinal (GI) cancer is a prevalent global health disease with a massive burden on health care providers. Internal and external factors such as obesity, smoking, diet (red meat), low socioeconomic status and infection with Helicobacter pylori are the critical risk factors of GI cancers. Flavonoids are natural phenolic compounds found abundantly in fruits and vegetables. Upon ingestion, 90% of flavonoids consumed require further enzymatic metabolism by the gut microbiome to enhance their bioavailability and absorption. Several epidemiological studies reported that consumption of flavonoids and their enzymatic conversion by gut microbes is strongly associated with the reduced risk of GI cancer development. This review summarizes the current knowledge on the enzymatic conversion of flavonoids by the human gut microbiome. It also addresses the underlying anti-GI cancer effects on metabolic pathways such as apoptosis and cellular proliferation. Overall, metabolites produced from flavonoid's enzymatic conversion illustrate anti-GI cancer effects, but the mechanisms of action need further clarification.

Chitosan-tripolyphosphate nanoparticles designed to encapsulate polyphenolic compounds for biomedical and pharmaceutical applications - A review

Plant-based polyphenols are natural compounds, present in fruits and vegetables. During recent years, polyphenols have gained special attention due to their nutraceutical and pharmacological activities for the prevention and treatment of human diseases. Nevertheless, their photosensitivity and low bioavailability, rapid metabolism and short biological half-life represent the major limitations for their use, which could be overcome by polyphenols encapsulation (flavonoids and non-flavonoids) into chitosan (CS)-tripolyphosphate (TPP) based nanoparticles (NP). In this review, we particularly focused on the ionic gelation method for the NP design. This contribution exhaustively discusses and compares results of scientific reports published in the last decade referring to ionic gelation applied for the protection, controlled and site-directed delivery of polyphenols. As a consequence, CS-TPP NP would constitute true platforms to transport polyphenols, or a combination of them, to be used for the designing of a new generation of drugs or nutraceuticals.

Smart biodegradable films based on chitosan/methylcellulose containing Phyllanthus reticulatus anthocyanin for monitoring the freshness of fish fillet

The current work aims to prepare biologically active and pH responsive smart films based on Chitosan (CS)/Methylcellulose (MC) matrix integrated with Phyllanthus reticulatus (PR) ripen fruit anthocyanin. The prepared smart films (CMPR) were fabricated through a cost-effective solvent casting technique. The existences of secondary interactions were confirmed by the FT-IR analysis. The smooth SEM images revealed the miscibility and compatibility of the CS/MC matrix with PR anthocyanin. The incorporation of PR anthocyanin significantly blocked the UV light transmission of the CS/MC films while slight decrease in the transparency was observed. The water solubility, moisture retention capacity, and water vapor transmission rate were significantly enhanced with an increase in the PR anthocyanin content. Additionally, the prepared CMPR smart films showed pink color in acidic pH while yellowish in basic pH solution and further exhibited strong antioxidant activity as well as antibacterial activity against the common foodborne pathogens such as S. aureus, P. aeruginosa, and E. coli. The CMPR smart film also displayed potential result for monitoring the fish fillet freshness at room temperature. The results proclaim that the prepared CMPR smart films could be utilized for quality assurance as well as shelf life extension of the marine food products.

Dietary Effects of Anthocyanins in Human Health: A Comprehensive Review

In recent years, the consumption of natural-based foods, including beans, fruits, legumes, nuts, oils, vegetables, spices, and whole grains, has been encouraged. This fact is essentially due to their content in bioactive phytochemicals, with the phenolic compounds standing out. Among them, anthocyanins have been a target of many studies due to the presence of catechol, pyrogallol, and methoxy groups in their chemical structure, which confer notable scavenging, anti-apoptotic, and anti-inflammatory activities, being already recommended as supplementation to mitigate or even attenuate certain disorders, such as diabetes, cancer, and cardiovascular and neurological pathologies. The most well-known anthocyanins are cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside. They are widespread in nature, being present in considerable amounts in red fruits and red vegetables. Overall, the present review intends to discuss the most recent findings on the potential health benefits from the daily intake of anthocyanin-rich foods, as well as their possible pharmacological mechanisms of action. However, before that, some emphasis regarding their chemical structure, dietary sources, and bioavailability was done.

In vitro gastrointestinal digestion impact on stability, bioaccessibility and antioxidant activity of polyphenols from wild and commercial blackberries (Rubus spp.)

Gastrointestinal digestion (GID) is a physiological process that transforms the stability, bioaccessibility and antioxidant activity (AOX) of polyphenols from blackberries (Rubus spp.). This study aimed to investigate the effect of the INFOGEST® GID protocol on the phenolic stability, bioaccessibility and AOX of Mexican wild (WB) and commercial (CB) blackberries. After GID, the total phenolic and anthocyanin contents in blackberries decreased by ≥68% and ≥74%, respectively. More than 40 phenolics were identified during GID; most of them degraded completely during digestion. GID had a negative effect on the AOX of both fruits (>50%), but WB showed the highest antioxidant activities, as assessed by the ORAC, DPPH, reducing power and β-carotene bleaching methods. In Caco-2 cells, the cell-based antioxidant activity of digested blackberries (p < 0.05) decreased by 48% in WB and by 56% in CB. The capacity to inhibit intracellular ROS decreased by 50% in WB and by up to 86% in CB, after digestion. GID is a complex process that impacts on the bioactive properties of food nutrients, especially phenolics. In vitro and cellular AOX of WB polyphenols withstood the gastrointestinal environment better than CB phenolics. The in vitro assays results suggest that phenolics from underutilized WB have a higher bioaccessibility and antioxidant capacity than the polyphenols from the most frequently consumed CB. However, whether this corresponds to a better bioaccessibility in humans remains to be determined in future work.

External dsRNA Downregulates Anthocyanin Biosynthesis-Related Genes and Affects Anthocyanin Accumulation in Arabidopsis thaliana

Exogenous application of double-stranded RNAs (dsRNAs) and small-interfering RNAs (siRNAs) to plant surfaces has emerged as a promising method for regulation of essential genes in plant pathogens and for plant disease protection. Yet, regulation of plant endogenous genes via external RNA treatments has not been sufficiently investigated. In this study, we targeted the genes of chalcone synthase (CHS), the key enzyme in the flavonoid/anthocyanin biosynthesis pathway, and two transcriptional factors, MYBL2 and ANAC032, negatively regulating anthocyanin biosynthesis in Arabidopsis. Direct foliar application of AtCHS-specific dsRNAs and siRNAs resulted in an efficient downregulation of the AtCHS gene and suppressed anthocyanin accumulation in A. thaliana under anthocyanin biosynthesis-modulating conditions. Targeting the AtMYBL2 and AtANAC032 genes by foliar dsRNA treatments markedly reduced their mRNA levels and led to a pronounced upregulation of the AtCHS gene. The content of anthocyanins was increased after treatment with AtMYBL2-dsRNA. Laser scanning microscopy showed a passage of Cy3-labeled AtCHS-dsRNA into the A. thaliana leaf vessels, leaf parenchyma cells, and stomata, indicating the dsRNA uptake and spreading into leaf tissues and plant individual cells. Together, these data show that exogenous dsRNAs were capable of downregulating Arabidopsis genes and induced relevant biochemical changes, which may have applications in plant biotechnology and gene functional studies.

Effects of Berry Anthocyanins on Cognitive Performance, Vascular Function and Cardiometabolic Risk Markers: A Systematic Review of Randomized Placebo-Controlled Intervention Studies in Humans

Supplementation with anthocyanins, which are a type of flavonoids mainly found in various berries, is hypothesized to be a promising approach to lower the risk of developing cognitive decline. The aim of this systematic review was to provide a comprehensive overview of dietary intervention trials describing effects of berry anthocyanins on cognitive performance in humans, while also addressing potential underlying mechanisms. A total of 1197 articles were identified through a systematic search, and 49 studies reporting effects on cognitive performance (n = 18), vascular function (n = 22), or cardiometabolic risk markers (n = 32) were included. Significant improvements were observed on memory, while some of the studies also reported effects on attention and psychomotor speed or executive function. Vascular function markers such as brachial artery flow-mediated vasodilation were also affected and consistent evidence was provided for the beneficial effects of berry anthocyanins on endothelial function. Finally, studies reported improvements in blood pressure, but effects on metabolic risk markers (e.g. carbohydrate and lipid metabolism) were less consistent. In conclusion, this review provides evidence for the beneficial effects of berry anthocyanins on cognitive performance as memory improved. Whether observed anthocyanin-induced improvements in vascular function and blood pressure underlie beneficial effects on cognitive performance warrants further study.

Melatonin Treatment to Pomegranate Trees Enhances Fruit Bioactive Compounds and Quality Traits at Harvest and during Postharvest Storage

The effect of melatonin pomegranate tree treatments on fruit quality and bioactive compounds with antioxidant activity at harvest and during storage at 10 °C for 60 days was assayed in two consecutive years, 2019 and 2020. In the first year, trees were treated with 0.1, 0.3 and 0.5 mM of melatonin along the developmental fruit growth cycle, and results showed that bioactive compounds (total phenolics and total and individual anthocyanins) and antioxidant activity at harvest were higher in fruits from melatonin-treated trees than in controls. Other fruit quality parameters, such as firmness, total soluble solids and aril red colour, were also increased as a consequence of melatonin treatment. In fruit from control tress, firmness and acidity levels decreased during storage, while increases occurred on total soluble solids, leading to fruit quality reductions. These changes were delayed, and even maintenance of total acidity was observed, in fruit from melatonin-treated trees with respect to controls, resulting in a fruit shelf-life increase. Moreover, concentration of phenolics and anthocyanins and antioxidant activity were maintained at higher levels in treated than in control fruits during the whole storage period. In general, all the mentioned effects were found at the highest level with the 0.1 mM melatonin dose, and then it was selected for repeating the experiment in the second year and results of the first year were confirmed. Thus, 0.1 mM melatonin treatment could be a useful tool to enhance aril content on bioactive compounds with antioxidant activity and health beneficial effects and to improve quality traits of pomegranate fruit, at harvest and during postharvest storage.

MYB-Mediated Regulation of Anthocyanin Biosynthesis

Anthocyanins are natural water-soluble pigments that are important in plants because they endow a variety of colors to vegetative tissues and reproductive plant organs, mainly ranging from red to purple and blue. The colors regulated by anthocyanins give plants different visual effects through different biosynthetic pathways that provide pigmentation for flowers, fruits and seeds to attract pollinators and seed dispersers. The biosynthesis of anthocyanins is genetically determined by structural and regulatory genes. MYB (v-myb avian myeloblastosis viral oncogene homolog) proteins are important transcriptional regulators that play important roles in the regulation of plant secondary metabolism. MYB transcription factors (TFs) occupy a dominant position in the regulatory network of anthocyanin biosynthesis. The TF conserved binding motifs can be combined with other TFs to regulate the enrichment and sedimentation of anthocyanins. In this study, the regulation of anthocyanin biosynthetic mechanisms of MYB-TFs are discussed. The role of the environment in the control of the anthocyanin biosynthesis network is summarized, the complex formation of anthocyanins and the mechanism of environment-induced anthocyanin synthesis are analyzed. Some prospects for MYB-TF to modulate the comprehensive regulation of anthocyanins are put forward, to provide a more relevant basis for further research in this field, and to guide the directed genetic modification of anthocyanins for the improvement of crops for food quality, nutrition and human health.

Mass spectrometry-based metabolomics for the discovery of candidate markers of flavonoid and polyphenolic intake in adults

Robust biological markers of dietary exposure are essential in improving the understanding of the link between diet and health outcomes. Polyphenolic compounds, including flavonoids, have been proposed to mitigate the risk of chronic diseases where oxidative stress and inflammation play a central role. Biomarkers can provide objective measurement of the levels of polyphenolic compounds. In this study, we provide methodology to identify potential candidate markers of polyphenol intake in human serum. Seventeen participants from the UK arm of the Global Allergy and Asthma Network of Excellence (GA²LEN) had their dietary intake estimated using a validated food frequency questionnaire, and serum samples were assessed using mass spectrometry to identify potential candidate markers. 144 features were assigned identities, of these we identified four biologically relevant compounds (rhamnazin 3-rutinoside, 2-galloyl-1,4-galactarolactone methyl ester, 2″,32″-di-O-p-coumaroylafzelin and cyclocommunin), which were significantly increased in the serum of participants with high predicted level of fruit and vegetable intake. 2-galloyl-1,4-galactarolactone methyl ester was strongly correlated with total flavonoids (r = 0.62; P = 0.005), flavan-3-ols (r = 0.67; P = 0.002) as well as with other four subclasses. Rhamnazin 3-rutinoside showed strong correlation with pro-anthocyanidins (r = 0.68; P = 0.001), flavones (r = 0.62; P = 0.005). Our results suggest that serum profiling for these compounds might be an effective way of establishing the relative intake of flavonoids and could contribute to improve the accuracy of epidemiological methods to ascertain flavonoid intake.

Investigation on spontaneous 4D changes in color and flavor of healthy 3D printed food materials over time in response to external or internal pH stimulus

This study aimed to investigate 4D changes in colors and flavors of 3D-printed healthy food products in response to an external or internal pH stimulus. The formulations obtained by 3D printing of multi-smart materials, comprised of the combination of red cabbage juice, vanillin powder, potato starch and different fruit juices were used. 3D printing ability of red cabbage juice and vanillin powder affected by different potato starch concentrations was first studied. Then, changes in color, texture, flavor (by E-nose) and taste (by E-tongue) induced by the stimulus were determined. Results revealed that the color of the 3D-printed product changed from blue (control sample) to red, purple, violet, blue, blue-green, and green-yellow colors when sprayed with pH solutions of 2, 3-4, 5-6, 7, 8-9, and 10, respectively. In addition, clear differences in aroma and taste profiles among pH samples were detected. Moreover, dried 4D product samples exhibited color and anthocyanins stability when stored in ambient temperature for three weeks. This study is important for manufacturing new healthy 3D-printed food products with desired and attractive sensory characteristics, which can be particularly significant to people with poor appetite.

Anthocyanins, Microbiome and Health Benefits in Aging

The percentage of individuals over the age of 60 is projected to reach 22% by 2050; chronic diseases associated with aging can present challenges for these individuals. Anthocyanins and the gut microbiome have each been studied as independent influencers of health. Both these factors have shown to have a positive effect on cardiovascular and bone health in individuals, as well as on the prevention or treatment of certain forms of cancers. Anthocyanins have shown to modulate the composition of the gut microbiome and may have overlapping mechanisms in the prevention and treatment of cardiovascular disease, cancer, neurodegenerative disorders and aging-associated bone loss. These health outcomes are responsible for the hospitalization and deaths of millions of Americans every year and they cost the United States billions of dollars each year to maintain, prevent and treat. Alternative methods of treatment and prevention are desired since conventional methods (surgical and pharmacological methods, physical therapy, etc.) can be costly and have significant side effects; evidence suggests that anthocyanins and the gut microbiome may be potential avenues for this. This review evaluates the findings of existing literature on the role of anthocyanins and the gut microbiome on health and their potential as a natural therapeutic agent or a target organ to provide an alternative to the conventional methods of disease prevention and treatment.

Carbohydrate Hydrolase-Inhibitory Activity of Juice-Based Phenolic Extracts in Correlation to Their Anthocyanin/Copigment Profile

Red fruits and their juices are rich sources of polyphenols, especially anthocyanins. Some studies have shown that such polyphenols can inhibit enzymes of the carbohydrate metabolism, such as α-amylase and α-glucosidase, that indirectly regulate blood sugar levels. The presented study examined the in vitro inhibitory activity against α-amylase and α-glucosidase of various phenolic extracts prepared from direct juices, concentrates, and purees of nine different berries which differ in their anthocyanin and copigment profile. Generally, the extracts with the highest phenolic content-aronia (67.7 ± 3.2 g GAE/100 g; cyanidin 3-galactoside; chlorogenic acid), pomegranate (65.7 ± 7.9 g GAE/100 g; cyanidin 3,5-diglucoside; punicalin), and red grape (59.6 ± 2.5 g GAE/100 g; malvidin 3-glucoside; quercetin 3-glucuronide)-showed also one of the highest inhibitory activities against α-amylase (326.9 ± 75.8 μg/mL; 789.7 ± 220.9 μg/mL; 646.1 ± 81.8 μg/mL) and α-glucosidase (115.6 ± 32.5 μg/mL; 127.8 ± 20.1 μg/mL; 160.6 ± 68.4 μg/mL) and, partially, were even more potent inhibitors than acarbose (441 ± 30 μg/mL; 1439 ± 85 μg/mL). Additionally, the investigation of single anthocyanins and glycosylated flavonoids demonstrated a structure- and size-dependent inhibitory activity. In the future in vivo studies are envisaged.