(Poly)phenol toxicity in vivo following oral administration: A targeted narrative review of (poly)phenols from green tea, grape, and anthocyanin-rich extracts

Application of polyphenols as natural antioxidants in edible oils: Current status, antioxidant mechanism, and advanced technology

Oxidation of edible oil, especially those rich in polyunsaturated fatty acids, remains an inevitable problem. Since synthesis antioxidants may have some side effects, countries have been encouraging the development of natural alternatives. Polyphenols are natural compounds demonstrating notable potential in mitigating oil oxidation, but the effectiveness of polyphenols in inhibiting oil oxidation seems to be influenced by their antioxidant mechanisms, components, solubility, and application forms. To promote polyphenol application in oils, the present study aims to provide a comprehensive summary of the antioxidant mechanism of polyphenols in vitro, the common polyphenols employed to inhibit oil oxidation, and the pivotal technologies for incorporating polyphenols with low-fat solubility into oils including esterification modification, co-extraction of polyphenols and oils, nano-emulsion, microcapsules, and oleogels. In addition, a strengths, weaknesses, opportunities, and threats analysis of polyphenol application in oil was conducted. This review will provide a guidance for the application of polyphenols in oils.

Bioavailability of Food Polyphenols: Current State of Knowledge

(Poly)phenols, including flavonoids, phenolic acids, and tannins, are a diverse class of compounds found in plant-based foods and beverages. Their bioavailability has been extensively described and detailed metabolic pathways elucidated. Although some parent (poly)phenols are absorbed intact in the small intestine, most pass to the colon where they are extensively catabolized and their microbial products absorbed into the circulation. The sum of the metabolites absorbed can reach almost 100% in some cases and in some individuals. In recent years, there have been three major areas of advancement: (a) comprehensive and systematic reviews have brought together bioavailability data, including detailed metabolic pathways in humans, and quantitative estimates of absorption and excretion; (b) the action and importance of the gut microbiota in (poly)phenol metabolism have been better defined and our understanding of the important role of the microbiota in intra- and interindividual variation has greatly expanded; and (c) strategies to improve (poly)phenol bioavailability such as encapsulation employing various nanoformulations or cyclodextrins have been developed.

Anthocyanin-Rich Fraction from Kum Akha Black Rice Attenuates NLRP3 Inflammasome-Driven Lung Inflammation In Vitro and In Vivo

BACKGROUND/OBJECTIVES

Chronic lower respiratory tract inflammation can result from exposure to bacterial particles, leading to the activation of the NLRP3 inflammasome pathway. These effects may cause irreversible respiratory damage, contributing to persistent lung injury and chronic obstructive pulmonary disease (COPD), as observed in long COVID or bacterial pneumonia in older adults' patients. Given its profound impact, the NLRP3 inflammasome has emerged as a key therapeutic target for mitigating aberrant inflammatory responses.

METHODS

In this study, we investigated the anti-inflammatory effects of Kum Akha black rice, a functional food, on the attenuation of NLRP3 inflammasome pathway using lipopolysaccharide-induced A549 lung epithelial cells and a C57BL/6NJcl mouse model. The anthocyanin-rich fraction from Kum Akha black rice germ and bran extract (KA1-P1) was obtained using a solvent-partitioned extraction technique.

RESULTS

KA1-P1 exhibited a high anthocyanin content (74.63 ± 1.66 mg/g extract) as determined by the pH differential method. The HPLC analysis revealed cyanidin-3-O-glucoside (C3G: 45.58 ± 0.48 mg/g extract) and peonidin-3-O-glucoside (P3G: 6.92 ± 0.29 mg/g extract) as its anthocyanin's active compounds. Additionally, KA1-P1 demonstrated strong antioxidant activity, as assessed by DPPH and ABTS assays. KA1-P1 (12.5-100 μg/mL) possessed inhibitory effects on LPS + ATP-induced A549 lung cells inflammation through the significant suppressions of NLRP3, IL-6, IL-1β, and IL-18 mRNA levels and the inhibition of cytokine secretions in a dose-dependent manner (p < 0.05). Mechanistic analysis revealed that KA1-P1 downregulated key proteins in the NLRP3 inflammasome pathway (NLRP3, ASC, pro-caspase-1, and cleaved-caspase-1). Furthermore, in vivo studies demonstrated that KA1-P1 significantly diminished LPS-induced lower respiratory inflammation in C57BL/6NJcl mice, as evidenced by the reduced bronchoalveolar lavage fluid and blood levels of inflammatory cytokines (IL-6, IL-1β, and IL-18) and diminished histopathological inflammatory lung lesions.

CONCLUSIONS

Overall, our findings suggest that the anti-inflammatory properties of KA1-P1 may support its application as a functional supplement or promote the consumption of pigmented rice among the elderly to mitigate chronic lower respiratory tract inflammation mediated by the NLRP3 inflammasome pathway.

Medical Benefits and Polymer Applications of Grapes

Grapes are a fruit with origins dating back to ancient times. Their first recorded use, as mentioned in the Bible, was in winemaking. The abundance of bioactive compounds in grapes makes them highly valuable. So far, many varieties of cultivated grapes have been developed for table grapes, wine grapes, and raisin production. In addition to these uses, since grapes contain a variety of nutrients, including resveratrol, flavonoids (such as flavonols, anthocyanins, and catechins), melatonin, vitamins, acids, tannins, and other antioxidants, grape extracts have been widely studied for medical applications. This paper reviews the medical effects of these compounds on cancer, cardiovascular disease, brain and neurological disorders, eye diseases, skin disorders, kidney health, diabetes, and gastric diseases, along with the medical applications of grapes in drug delivery, wound dressing, and tissue engineering. In addition, the limitations of the grapes-derived polymers and future research perspectives are discussed. These benefits highlight that the value of grapes extends far beyond their traditional use in wine and raisin production.

A comprehensive review of effects of ultrasound pretreatment on processing technologies for food allergens: Allergenicity, nutritional value, and technofunctional properties and safety assessment

Many proteins are essential food components but also major allergens. Reducing protein allergenicity while preserving its nutritional value and technofunctional properties has always been the goal of the food industry. Ultrasound (US) is a green processing method for modifying proteins. In addition, US pretreatment combined with other processing techniques (USPCT) has been increasingly used in the food industry. Therefore, this review presents an overview of recent advances in the impact of US and USPCT (US-combined enzymatic hydrolysis [USCE], US-combined glycation [USCG], and US-combined polyphenol conjugation [USCP]) on the allergenicity, nutritional value, and technofunctional properties of food allergens. We discuss the potential mechanisms, advantages, and limitations of these technologies for improving the properties of proteins and analyze their safety, challenges, and corresponding solutions. It was found that USPCT can improve the efficiency and effectiveness of different methods, which in turn can be more effective in reducing protein allergenicity and improving the nutritional value and functional properties of processed products. Future research should start with new processing methods, optimization of process conditions, industrial production, and the use of new research techniques to promote technical progress. This paper is expected to provide reference for the development of high-quality hypoallergenic protein raw materials.

Antibacterial, Antifungal, Antiviral Activity, and Mechanisms of Action of Plant Polyphenols

This review describes the enhanced classification of polyphenols into flavonoids, lignans, phenolic acids, stilbenes, and tannins. Its focus is the natural sources of polyphenols and an in-depth discussion of their antibacterial, antifungal, and antiviral activity. Besides a broad literature overview, this paper contains authors' experimental data according to some daily consumed vegetables such as tomatoes, different varieties of onion, garlic, parsley, and cayenne pepper and the probable relation of these activities to polyphenols. The isolation of polyphenols via conventional and ultrasonic, pressurized liquids and pulse-field extractions, as well as their methods for detection and determination, are interpreted as well. The main mechanisms by which polyphenols inhibit the growth of bacteria, fungi, and viruses, such as protein synthesis, cell membrane destabilization, and ROS production induction, are in focus. Data on polyphenol concentrations and their respective MIC or the inhibition zone diameters of different bacterial and fungal species and suppressing viral replication are depicted. The toxicity of polyphenols in vitro, ex vivo, and in vivo towards microorganisms and human/animal cells, and the safety of the polyphenols applied in clinical and industrial applications are expanded. This review also characterizes the antimicrobial effects of some chemically synthesized polyphenol derivatives. Biotechnological advances are also reported, especially the entrapment of polyphenols in biocompatible nanoparticles to enhance their bioavailability and efficacy. Polyphenols are promising for exploring molecules' novel antimicrobial substances and paving the path for effective novel antimicrobial agents' discovery, taking into consideration their positives and negatives.

Aronia-derived anthocyanins and metabolites ameliorate TNFα-induced disruption of myogenic differentiation in satellite cells

This study investigates the effects of Aronia berries, their primary anthocyanins and other second metabolites-mimicking dietary anthocyanin consumption-on enhancing muscular myogenesis under chronic inflammation. Murine muscle satellite cells (MuSCs) were cultured ex vivo, allowing for expansion and differentiation into myotubes. Myogenic differentiation was disrupted by TNFα at both early and terminal stages, with treatment using Aronia berries applied at physiologically relevant concentrations alongside TNFα. The results demonstrated that Aronia berries treatments, particularly phenolic metabolites, significantly stimulated the proliferative capacity of MuSCs. Furthermore, Aronia berries treatment enhanced early-stage myogenesis, marked by increased MymX and MyoG expression and nascent myotube formation, with metabolites showing the most pronounced effects. Aronia berry powder and individual anthocyanins exerted milder regulatory effects. Similar trends were observed during terminal differentiation, where Aronia berries treatment promoted myotube growth and inhibited TNFα-induced inflammatory atrophic ubiquitin-conjugating activity. Additionally, the secondary metabolites of Aronia berries significantly prevented muscle-specific ubiquitination in the dexamethasone-induced atrophy model. Overall, the treatment with Aronia berries enhanced myogenesis in a cellular model of chronic muscular inflammation, with Aronia-derived metabolites showing the strongest response, likely through TLR4/NF-κB modulation. In this case, enhanced regeneration capacity and anti-atrophy potential were associated with TLR4/NF-κB modulation.

Small phenolic compounds as potential endocrine disruptors interacting with estrogen receptor alpha

The human body is regularly exposed to simple catechols and small phenols originating from our diet or as a consequence of exposure to various industrial products. Several biological properties have been associated with these compounds such as antioxidant, anti-inflammatory, or antiplatelet activity. Less explored is their potential impact on the endocrine system, in particular through interaction with the alpha isoform of the estrogen receptor (ERα). In this study, human breast cancer cell line MCF-7/S0.5 was employed to investigate the effects on ERα of 22 closely chemically related compounds (15 catechols and 7 phenols and their methoxy derivatives), to which humans are widely exposed. ERα targets genes ESR1 (ERα) and TFF1, both on mRNA and protein level, were chosen to study the effect of the tested compounds on the mentioned receptor. A total of 7 compounds seemed to impact mRNA and protein expression similarly to estradiol (E2). The direct interaction of the most active compounds with the ERα ligand binding domain (LBD) was further tested in cell-free experiments using the recombinant form of the LBD, and 4-chloropyrocatechol was shown to behave like E2 with about 1/3 of the potency of E2. Our results provide evidence that some of these compounds can be considered potential endocrine disruptors interacting with ERα.

Polyphenol-Rich Extract of Apocynum venetum L. Leaves Protects Human Retinal Pigment Epithelial Cells against High Glucose-Induced Damage through Polyol Pathway and Autophagy

Diabetic retinopathy (DR) is a specific microvascular problem of diabetes, which is mainly caused by hyperglycemia and may lead to rapid vision loss. Dietary polyphenols have been reported to decrease the risk of DR. Apocynum venetum L. leaves are rich in polyphenolic compounds and are popular worldwide for their health benefits as a national tea drink. Building on previous findings of antioxidant activity and aldose reductase inhibition of A. venetum, this study investigated the chemical composition of polyphenol-rich extract of A. venetum leaves (AVL) and its protective mechanism on ARPE-19 cells in hyperglycemia. Ninety-three compounds were identified from AVL by LC-MS/MS, including sixty-eight flavonoids, twenty-one organic acids, and four coumarins. AVL regulated the polyol pathway by decreasing the expression of aldose reductase and the content of sorbitol, enhancing the Na+K+-ATPase activity, and weakening intracellular oxidative stress effectively; it also could regulate the expression of autophagy-related proteins via the AMPK/mTOR/ULK1 signaling pathway to maintain intracellular homeostasis. AVL could restore the polyol pathway, inhibit oxidative stress, and maintain intracellular autophagy to protect cellular morphology and improve DR. The study reveals the phytochemical composition and protective mechanisms of AVL against DR, which could be developed as a functional food and/or candidate pharmaceutical, aiming for retina protection in diabetic retinopathy.

Protein-phenolic interactions and reactions: Discrepancies, challenges, and opportunities

Although noncovalent interactions and covalent reactions between phenolic compounds and proteins have been investigated across diverse scientific disciplines, a comprehensive understanding and identification of their products remain elusive. This review will initially outline the chemical framework and, subsequently, delve into unresolved or debated chemical and functional food-related implications, as well as forthcoming challenges in this topic. The primary objective is to elucidate the multiple aspects of protein-phenolic interactions and reactions, along with the underlying overwhelming dynamics and possibilities of follow-up reactions and potential crosslinking between proteins and phenolic compounds. The resulting products are challenging to identify and characterize analytically, as interactions and reactions occur concurrently, mutually influencing each other. Moreover, they are being modulated by various conditions such as the reaction parameters and, obviously, the chemical structure. Additionally, this review delineates the resulting discrepancies and challenges of properties and attributes such as color, taste, foaming, emulsion and gel formation, as well as effects on protein digestibility and allergenicity. Ultimately, this review is an opinion paper of a group of experts, dealing with these challenges for quite a while and aiming at equipping researchers with a critical and systematic approach to address current research gaps concerning protein-phenolic interactions and reactions.

Greasing the Wheels of Pharmacotherapy for Colorectal Cancer: the Role of Natural Polyphenols

PURPOSE OF REVIEW

The main purpose of this review, mainly based on preclinical studies, is to summarize the pharmacological and biochemical evidence regarding natural polyphenols against colorectal cancer and highlight areas that require future research.

RECENT FINDINGS

Typically, colorectal cancer is a potentially preventable and curable cancer arising from benign precancerous polyps found in the colon's inner lining. Colorectal cancer is the third most common cancer, with a lifetime risk of approximately 4 to 5%. Genetic background and environmental factors play major roles in the pathogenesis of colorectal cancer. Theoretically, a multistep process of colorectal carcinogenesis provides enough time for anti-tumor pharmacotherapy of colorectal cancer. Chronic colonic inflammation, oxidative stress, and gut microbiota imbalance have been found to increase the risk for colorectal cancer development by creating genotoxic stress within the intestinal environment to generate genetic mutations and epigenetic modifications. Currently, numerous natural polyphenols have shown anti-tumor properties against colorectal cancer in preclinical research, especially in colorectal cancer cell lines. In this review, the current literature regarding the etiology and epidemiology of colorectal cancer is briefly outlined. We highlight the findings of natural polyphenols in colorectal cancer from in vitro and in vivo studies. The scarcity of human trials data undermines the clinical use of natural polyphenols as anti-colorectal cancer agents, which should be undertaken in the future.

Natural Functional Beverages as an Approach to Manage Diabetes

Diabetes mellitus is a chronic disease, commonly associated with unhealthy habits and obesity, and it is becoming a serious health issue worldwide. As a result, new approaches to treat diabetes are required, and a movement towards more natural approaches is emerging. Consuming fruit and vegetables is advised to prevent diabetes since they contain several bioactive compounds. A simple and effective strategy to include them in the diets of diabetic and obese people is through beverages. This review aims to report the anti-diabetic potentials of different vegetable and fruit beverages. These functional beverages demonstrated in vitro potential to inhibit α-glucosidase and α-amylase enzymes and to improve glucose uptake. In vivo, beverage consumption showed a reduction of blood glucose, increase of insulin tolerance, improvement of lipid profile, control of obesity, and reduction of oxidative stress. This suggests the potential of vegetable- and fruit-based functional beverages to be used as a natural innovative therapy for the management of diabetes.

Safety assessment of European cranberrybush (Viburnum opulus L.) fruit juice: Acute and subacute oral toxicity

European cranberrybush (ECB) (Viburnum opulus L.) fruits are abundant in phenolic compounds associated with various health benefits. However, the toxicity and safety of ECB juice have not been systematically studied. In the present study, acute and subacute oral toxicities of ECB fruit juice were evaluated on Sprague-Dawley rats and BALB/c mice to establish a toxicity profile. In acute tests, a single administration of 2000 mg/kg body weight of extract to rats exhibited no clinical signs of toxicity or mortality, indicating that the lethal dose (LD50) was over 2000 mg/kg. In subacute tests, repeated administration for 28 days at 0 (control), 500, and 2000 mg/kg doses of extract in mice did not display adverse clinical signs or deaths. However, in the 2000 mg/kg subacute group, platelet counts were significantly high, which correlated with histopathological analyses revealing that ECB extract at 2000 mg/kg was toxic to the kidney, liver, and adipose tissue. The NOAEL value of ECB extract was found as 500 mg/kg/day, but further sub-chronic and chronic toxicity studies are warranted to comprehensively evaluate the long-term safety implications. The study's results emphasize the importance of considering the dosage of dietary supplements containing high levels of phenolic compounds over an extended period to avoid potential cumulative effects from prolonged consumption of high doses.

Evaluation of Different Advanced Approaches to Simulation of Dynamic In Vitro Digestion of Polyphenols from Different Food Matrices-A Systematic Review

Phenolic compounds have become interesting bioactive antioxidant compounds with implications for obesity, cancer and inflammatory gastrointestinal pathologies. As the influence of digestion and gut microbiota on antioxidant behavior is yet to be completely elucidated, and due to limitations associated to in vivo studies, dynamic in vitro gastrointestinal models have been promoted. A systematic review was conducted of different databases (PubMed, Web of Science and Scopus) following PRISMA guidelines to assess different dynamic digestion models and assay protocols used for phenolic compound research regarding bioaccesibility and interaction with colonic microbiota. Of 284 records identified, those including dynamic multicompartmental digestion models for the study of phenolic compound bioaccesibility, bioactivity and the effects of microbiota were included, with 57 studies meeting the inclusion criteria. Different conditions and experimental configurations as well as administered doses, sample treatments and microbiological assays of dynamic digestion studies on polyphenols were recorded and compared to establish their relevance for the dynamic in vitro digestion of phenolic compounds. While similarities were observed in certain experimental areas, a high variability was found in others, such as administered doses. A description of considerations on the study of the digestion of phenolic compounds is proposed to enhance comparability in research.

Treatment of High-Polyphenol-Content Waters Using Biotechnological Approaches: The Latest Update

Polyphenols and their intermediate metabolites are natural compounds that are spread worldwide. Polyphenols are antioxidant agents beneficial for human health, but exposure to some of these compounds can be harmful to humans and the environment. A number of industries produce and discharge polyphenols in water effluents. These emissions pose serious environmental issues, causing the pollution of surface or groundwater (which are used to provide drinking water) or harming wildlife in the receiving ecosystems. The treatment of high-polyphenol-content waters is mandatory for many industries. Nowadays, biotechnological approaches are gaining relevance for their low footprint, high efficiency, low cost, and versatility in pollutant removal. Biotreatments exploit the diversity of microbial metabolisms in relation to the different characteristics of the polluted water, modifying the design and the operational conditions of the technologies. Microbial metabolic features have been used for full or partial polyphenol degradation since several decades ago. Nowadays, the comprehensive use of biotreatments combined with physical-chemical treatments has enhanced the removal rates to provide safe and high-quality effluents. In this review, the evolution of the biotechnological processes for treating high-polyphenol-content water is described. A particular emphasis is given to providing a general concept, indicating which bioprocess might be adopted considering the water composition and the economic/environmental requirements. The use of effective technologies for environmental phenol removal could help in reducing/avoiding the detrimental effects of these chemicals. In addition, some of them could be employed for the recovery of beneficial ones.

Efficacy and safety of dietary polyphenol supplementation in the treatment of non-alcoholic fatty liver disease: A systematic review and meta-analysis

Background

Dietary polyphenol treatment of non-alcoholic fatty liver disease (NAFLD) is a novel direction, and the existing clinical studies have little effective evidence for its therapeutic effect, and some studies have inconsistent results. The effectiveness of dietary polyphenols in the treatment of NAFLD is still controversial. The aim of this study was to evaluate the therapeutic efficacy of oral dietary polyphenols in patients with NAFLD.

Methods

The literature (both Chinese and English) published before 30 April 2022 in PubMed, Cochrane, Medline, CNKI, and other databases on the treatment of NAFLD with dietary polyphenols was searched. Manual screening, quality assessment, and data extraction of search results were conducted strictly according to the inclusion and exclusion criteria. RevMan 5.3 software was used to perform the meta-analysis.

Results

The RCTs included in this study involved dietary supplementation with eight polyphenols (curcumin, resveratrol, naringenin, anthocyanin, hesperidin, catechin, silymarin, and genistein) and 2,173 participants. This systematic review and meta-analysis found that 1) curcumin may decrease body mass index (BMI), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Triglycerides (TG) total cholesterol (TC), and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) compared to placebo; and curcumin does not increase the occurrence of adverse events. 2) Although the meta-analysis results of all randomized controlled trials (RCTs) did not reveal significant positive changes, individual RCTs showed meaningful results. 3) Naringenin significantly decreased the percentage of NAFLD grade, TG, TC, and low-density lipoprotein cholesterol (LDL-C) and increased high-density lipoprotein cholesterol (HDL-C) but had no significant effect on AST and ALT, and it is a safe supplementation. 4) Only one team presents a protocol about anthocyanin (from Cornus mas L. fruit extract) in the treatment of NAFLD. 5) Hesperidin may decrease BMI, AST, ALT, TG, TC, HOMA-IR, and so on. 6) Catechin may decrease BMI, HOMA-IR, and TG level, and it was well tolerated by the patients. 7) Silymarin was effective in improving ALT and AST and reducing hepatic fat accumulation and liver stiffness in NAFLD patients.

Conclusion

Based on current evidence, curcumin can reduce BMI, TG, TC, liver enzymes, and insulin resistance; catechin can reduce BMI, insulin resistance, and TG effectively; silymarin can reduce liver enzymes. For resveratrol, naringenin, anthocyanin, hesperidin, and catechin, more RCTs are needed to further evaluate their efficacy and safety.