Green tea extract and (-)-epigallocatechin-3-gallate, the major tea catechin, exert oxidant but lack antioxidant activities

Harnessing the Power of Polyphenols: A New Frontier in Disease Prevention and Therapy

There are a wide variety of phytochemicals collectively known as polyphenols. Their structural diversity results in a broad range of characteristics and biological effects. Polyphenols can be found in a variety of foods and drinks, including fruits, cereals, tea, and coffee. Studies both in vitro and in vivo, as well as clinical trials, have shown that they possess potent antioxidant activities, numerous therapeutic effects, and health advantages. Dietary polyphenols have demonstrated the potential to prevent many health problems, including obesity, atherosclerosis, high blood sugar, diabetes, hypertension, cancer, and neurological diseases. In this paper, the protective effects of polyphenols and the mechanisms behind them are investigated in detail, citing the most recent available literature. This review aims to provide a comprehensive overview of the current knowledge on the role of polyphenols in preventing and managing chronic diseases. The cited publications are derived from in vitro, in vivo, and human-based studies and clinical trials. A more complete understanding of these naturally occurring metabolites will pave the way for the development of novel polyphenol-rich diet and drug development programs. This, in turn, provides further evidence of their health benefits.

Reactive Carbonyl Species Scavenger: Epigallocatechin-3-Gallate

Epigallocatechin-3-gallate (EGCG), a prominent polyphenol found abundantly in tea, has garnered significant attention for its potential in preventing and ameliorating a wide range of diseases. Its remarkable antioxidant properties and ability to capture reactive carbonyl species make it a key player among tea's polyphenolic components. This paper delves into the synthesis and origins of both EGCG and reactive carbonyl species (RCS), emphasizing the toxicity of RCS in various food sources and their formation during food processing. Understanding EGCG's capability to capture and metabolize RCS is crucial for harnessing its health benefits. Thus, this paper explores the underlying mechanisms of EGCG for RCS inhibition and its role in capturing these compounds to generate EGCG-RCS adducts. And the absorption and metabolism of EGCG-RCS adducts is also discussed.

Tannin complexation with metal ions and its implication on human health, environment and industry: An overview

Tannins, also known as plant polyphenols (PPs), are secondary metabolites widely existing in higher plants and are a kind of natural renewable resource with wide distribution, variety and quantity. Tannin has become an important class of fine chemicals due to the easily modified molecular structure and the properties of antibacterial and antioxidant, combining with protein and complexing with metal ion. Besides being used for tanning leather, tannins are also widely used in wood adhesive, concrete water-reducing agents, oil drilling fluid viscosity-reducing agents, pharmaceutical, mineral processing, water treatment, gas desulfurization, metal anticorrosion, wood anticorrosion, printing and dyeing, liquor clarification, oil antioxidant, daily chemical products and other products preparation. There are two groups of tannins: condensed tannins (CTs) (flavonoid-derived proanthocyanidins) and hydrolysable tannins (HTs) (gallic acid ester-derived). Tannins can form complexes with metals through the ortho-dihydroxyphenolic group(s), especially with transition metals. The structure-activity relationships, stoichiometry, and origin of the insolubility of which were emphasized. Furthermore, this paper proposed an in-depth discussion of the associations of tannins-metal complexes in human health, environment and industries.

Intestinal polyphenol antioxidant activity involves redox signaling mechanisms facilitated by aquaporin activity

Ascertaining whether dietary polyphenols evoke an antioxidant or prooxidant activity, which translates to a functional role required to maintain intestinal cell homeostasis continues to be an active and controversial area of research for food chemists and biochemists alike. We have proposed that the paradoxical function of polyphenols to autoxidize to generate H2O2 is a required first step in the capacity of some plant phenolics to function as intracellular antioxidants. This is based on the fact that cell redox homeostasis is achieved by a balance between H2O2 formation and subsequent outcomes of antioxidant systems function. Maintaining optimal extracellular and intracellular H2O2 concentrations is required for cell survival, since low levels are important to upregulate endogenous antioxidant capacity; whereas, concentrations that go beyond homeostatic control typically result in an inflammatory response, growth arrest, or eventual cell death. Aquaporins (AQPs) are a family of water channel membrane proteins that facilitate cellular transportation of water and other small molecule-derived solutes, such as H2O2, in all organisms. In the intestine, AQPs act as gatekeepers to regulate intracellular uptake of H2O2, generated from extracellular polyphenol autoxidation, thus enabling an intracellular cell signaling responses to mitigate onset of oxidative stress and intestinal inflammation. In this review, we highlight the potential role of AQPs to control important underlying mechanisms that define downstream regulation of intestinal redox homeostasis, specifically. It has been established that polyphenols that undergo oxidation to the quinone form, resulting in subsequent adduction to a thiol group on Keap1-Nrf2 complex, trigger Nrf2 activation and a cascade of indirect intracellular antioxidant effects. Here, we propose a similar mechanism that involves H2O2 generated from specific dietary polyphenols with a predisposition to undergo autoxidation. The ultimate bioactivity is regulated and expressed by AQP membrane function and thus, by extension, represents expression of an intracellular antioxidant chemoprotection mechanism.

Dietary Epigallocatechin-3-Gallate (EGCG) Improves Nonspecific Immune Response of Chinese Rice Field Eel (Monopterus albus)

Epigallocatechin-3-gallate (EGCG) has been recognized as a potential additive for aquafeeds due to its beneficial biological functions. In order to evaluate the potential application of EGCG in Chinese rice field eel (Monopterus albus), six isonitrogenous and isolipidic diets containing 0, 25, 50, 100, 200, and 400 mg/kg EGCG were formulated and were fed to Monopterus albus (M. albus) for 9 weeks. The results showed that M. albus fed diets containing 0 and 100 mg/kg EGCG presented higher weight again and specific growth rate than the other groups. Fish fed with 25, 50, and 400 mg/kg EGCG displayed lower whole-body lipid content. Serum aspartate aminotransferase (AST) concentration significantly decreased in EGCG treated groups with the exception of 100 mg/kg group. Hepatic catalase (CAT) activity and glutathione (GSH) concentration decreased as EGCG level increased while malondialdehyde (MDA) concentration showed an opposite trend. EGCG supplementation resulted in a promoted lysozyme (LZM) activity and immunoglobulin M (IgM) level in the liver of M. albus. Furthermore, transcription of three immune related genes including major histocompatibility complex (mhc-2α), hepcidin, and interleukin-8 (il-8) mRNAs was upregulated by EGCG treatment; while transcription of interleukin-6 (il-6) and nuclear factor kappa-B (nf-kb) genes was downregulated. Results also showed a linear relation between EGCG inclusion level and parameters of AST, CAT, GSH, MDA, LZM, IgM, and immune-related genes transcriptions. In summary, it could be suggested that EGCG supplementation enhanced the nonspecific immune response of the Chinese rice field eel. Based on the broken-line regression analysis of IgM, the optimal dietary EGCG supplementation for M. albus was estimated to be 109.81 mg/kg.

Potential Benefits of Antioxidant Phytochemicals in Type 2 Diabetes

The clinical relationship between diabetes and inflammation is well established. Evidence clearly indicates that disrupting oxidant-antioxidant equilibrium and elevated lipid peroxidation could be a potential mechanism for chronic kidney disease associated with type 2 diabetes mellitus (T2DM). Under diabetic conditions, hyperglycemia, especially inflammation, and increased reactive oxygen species generation are bidirectionally associated. Inflammation, oxidative stress, and tissue damage are believed to play a role in the development of diabetes. Although the exact mechanism underlying oxidative stress and its impact on diabetes progression remains uncertain, the hyperglycemia-inflammation-oxidative stress interaction clearly plays a significant role in the onset and progression of vascular disease, kidney disease, hepatic injury, and pancreas damage and, therefore, holds promise as a therapeutic target. Evidence strongly indicates that the use of multiple antidiabetic medications fails to achieve the normal range for glycated hemoglobin targets, signifying treatment-resistant diabetes. Antioxidants with polyphenols are considered useful as adjuvant therapy for their potential anti-inflammatory effect and antioxidant activity. We aimed to analyze the current major points reported in preclinical, in vivo, and clinical studies of antioxidants in the prevention or treatment of inflammation in T2DM. Then, we will share our speculative vision for future diabetes clinical trials.

Cell Survival, Death, and Proliferation in Senescent and Cancer Cells: the Role of (Poly)phenols

Cellular senescence has long been considered a permanent state of cell cycle arrest occurring in proliferating cells subject to different stressors, used as a cellular defense mechanism from acquiring potentially harmful genetic faults. However, recent studies highlight that senescent cells might also alter the local tissue environment and concur to chronic inflammation and cancer risk by secreting inflammatory and matrix remodeling factors, acquiring a senescence-associated secretory phenotype (SASP). Indeed, during aging and age-related diseases, senescent cells amass in mammalian tissues, likely contributing to the inevitable loss of tissue function as we age. Cellular senescence has thus become one potential target to tackle age-associated diseases as well as cancer development. One important aspect characterizing senescent cells is their telomere length. Telomeres shorten as a consequence of multiple cellular replications, gradually leading to permanent cell cycle arrest, known as replicative senescence. Interestingly, in the large majority of cancer cells, a senescence escape strategy is used and telomere length is maintained by telomerase, thus favoring cancer initiation and tumor survival. There is growing evidence showing how (poly)phenols can impact telomere maintenance through different molecular mechanisms depending on dose and cell phenotypes. Although normally, (poly)phenols maintain telomere length and support telomerase activity, in cancer cells this activity is negatively modulated, thus accelerating telomere attrition and promoting cancer cell death. Some (poly)phenols have also been shown to exert senolytic activity, thus suggesting both antiaging (directly eliminating senescent cells) and anticancer (indirectly, via SASP inhibition) potentials. In this review, we analyze selective (poly)phenol mechanisms in senescent and cancer cells to discriminate between in vitro and in vivo evidence and human applications considering (poly)phenol bioavailability, the influence of the gut microbiota, and their dose-response effects.

Green tea polyphenol EGCg induces cell fusion via reactive oxygen species

Background

Osteoclasts are multinucleated cells formed by macrophage cell fusion that are responsible for bone resorption. Previously, we found that treating osteoclastic progenitor cells with (-)-epigallocatechin gallate (EGCg) increased cell fusion. In this study, we aimed to identify factors involved in the cell fusion induced by EGCg.

Methods

We hypothesized that EGCg-induced oxidative stress might be involved in cell fusion, and used macrophage cell line RAW264.7 cells. We evaluated cell fusion activity after adding the antioxidants N-acetyl-l-cysteine (NAC) or catalase in addition to EGCg. The mRNA expressions of genes related to cell fusion and bone resorption were quantified by real-time PCR. Finally, we added hydrogen peroxide and examined its effects on cell fusion and TRAP activity.

Results

EGCg-induced cell fusion was strongly inhibited by the addition of NAC in a dose-dependent manner (EGCg with 5 mM NAC; decreased to 1.5%; p < 0.05), while the inhibitory effect of catalase was limited (EGCg with 500 U/mL catalase; decreased to 27.7%; p < 0.05). DC-STAMP expression was significantly upregulated by EGCg compared with the untreated group, and the upregulation was significantly suppressed by 5 mM NAC. Conversely, Nfatc1 and TRAP expression were not upregulated by EGCg. These results suggest that EGCg induces DC-STAMP expression via reactive oxygen species production, which regulates cell fusion but does not affect the osteoclastic pathway. Although treatment with hydrogen peroxide promoted the formation of multinucleated cells, no increase in TRAP activity was observed, which was similar to EGCg treatment.

Conclusions

This study suggests that the increased cell fusion by EGCg may be induced by oxidative stress due to reactive oxygen species production.

The Effects of Green Tea Catechins in Hematological Malignancies

Green tea catechins are bioactive polyphenol compounds which have attracted significant attention for their diverse biological activities and potential health benefits. Notably, epigallocatechin-3-gallate (EGCG) has emerged as a potent apoptosis inducer through mechanisms involving caspase activation, modulation of Bcl-2 family proteins, disruption of survival signaling pathways and by regulating the redox balance, inducing oxidative stress. Furthermore, emerging evidence suggests that green tea catechins can modulate epigenetic alterations, including DNA methylation and histone modifications. In addition to their apoptotic actions, ROS signaling effects and reversal of epigenetic alterations, green tea catechins have shown promising results in promoting the differentiation of leukemia cells. This review highlights the comprehensive actions of green tea catechins and provides valuable insights from clinical trials investigating the therapeutic potential of green tea catechins in leukemia treatment. Understanding these multifaceted mechanisms and the outcomes of clinical trials may pave the way for the development of innovative strategies and the integration of green tea catechins into clinical practice for improving leukemia patient outcomes.

New Insights into Herb-Induced Liver Injury

Significance: Herbs are widely used worldwide. However, inappropriate use of some of the herbs can lead to herb-induced liver injury (HILI). Intriguingly, HILI incidents are on the rise, and our understanding of the underlying etiologies is in progress, and hence, an update on the current status of incidents as well as our understanding on the etiologies of HILI is appropriate. Recent Advances: HILI reports due to the use of some herbs that are traditionally considered to be safe are also on the rise. Furthermore, HILI due to the use of certain herbs in combination with other herbs (herb-herb interaction [HHI]) or non-herb components (herb-drug interaction [HDI]) has also been reported, suggesting a potentially important new type of inappropriate use of herbs. Critical Issues: Updated overviews focus on the epidemiology, etiology, phenotypes, and risk factors of HILI, as well as HDI and HHI, and analysis on several types of newly reported "toxic" effects of herbs based on types of hepatotoxicity and the HILI mechanisms. Future Directions: HILI will continue to be a significant public health challenge in the near future. In the light of the lack of broadly available guidelines and regulations for proper and safe uses of herbs worldwide, raising the public awareness of HILI will remain one of the most effective measures. In particular, it should include a better understanding of the contributing factors; a more detail subclassification and description of HILI, better characterization of the components/substances that could induce HILI; and development of HILI diagnosis based on the Roussel Uclaf Causality Assessment Method (RUCAM). Antioxid. Redox Signal. 38, 1138-1149.

Expected and Unexpected Effects of Pharmacological Antioxidants

In this review, we have collected the existing data on the bioactivity of antioxidants (N-acetylcysteine, polyphenols, vitamin C) which are traditionally used in experimental biology and, in some cases, in the clinic. Presented data show that, despite the capacity of these substances to scavenge peroxides and free radicals in cell-free systems, their ability to exhibit these properties in vivo, upon pharmacological supplementation, has not been confirmed so far. Their cytoprotective activity is explained mainly by the ability not to suppress, but to activate multiple redox pathways, which causes biphasic hormetic responses and highly pleiotropic effects in cells. N-acetylcysteine, polyphenols, and vitamin C affect redox homeostasis by generating low-molecular-weight redox-active compounds (H₂O₂ or H₂S), known for their ability to stimulate cellular endogenous antioxidant defense and promote cytoprotection at low concentrations but exert deleterious effects at high concentrations. Moreover, the activity of antioxidants strongly depends on the biological context and mode of their application. We show here that considering the biphasic and context-dependent response of cells on the pleiotropic action of antioxidants can help explain many of the conflicting results obtained in basic and applied research and build a more logical strategy for their use.

Bioaccessibility and Bioavailability of Diet Polyphenols and Their Modulation of Gut Microbiota

It is generally accepted that diet-derived polyphenols are bioactive compounds with several potentially beneficial effects on human health. In general, polyphenols have several chemical structures, and the most representative are flavonoids, phenolic acids, and stilbenes. It should be noted that the beneficial effects of polyphenols are closely related to their bioavailability and bioaccessibility, as many of them are rapidly metabolized after administration. Polyphenols-with a protective effect on the gastrointestinal tract-promote the maintenance of the eubiosis of the intestinal microbiota with protective effects against gastric and colon cancers. Thus, the benefits obtained from dietary supplementation of polyphenols would seem to be mediated by the gut microbiota. Taken at certain concentrations, polyphenols have been shown to positively modulate the bacterial component, increasing Lactiplantibacillus spp. and Bifidobacterium spp. involved in the protection of the intestinal barrier and decreasing Clostridium and Fusobacterium, which are negatively associated with human well-being. Based on the diet-microbiota-health axis, this review aims to describe the latest knowledge on the action of dietary polyphenols on human health through the activity of the gut microbiota and discusses micro-encapsulation of polyphenols as a strategy to improve the microbiota.

Evaluation of the synergistic effects of epigallocatechin-3-gallate-loaded PEGylated-PLGA nanoparticles with nimodipine against neuronal injury after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating subtype of stroke with high mortality and morbidity. Although serious side effects might occur, nimodipine, a second-generation 1,4-dihydropyridine calcium channel blocker, is clinically used to improve neurological outcomes after SAH. Recently, (-)-epigallocatechin-3-gallate (EGCG) has been reported to inhibit Ca²⁺ overloading-induced mitochondrial dysfunction, oxidative stress, and neuronal cell death after SAH; however, low bioavailability, instability, and cytotoxicity at a high dose limited the clinical application of EGCG. To overcome these limitations, PEGylated-PLGA EGCG nanoparticles (EGCG-NPs) were constructed to enhance the bioavailability by using the double-emulsion method. Antioxidative activity, cytotoxicity, behavioral, and immunohistochemistry studies were carried out to determine the neuroprotective effectiveness after cotreatment with EGCG-NPs (75 mg/kg/d preconditioning for 7 days before SAH) and nimodipine (10 mg/kg/d after 30 min of SAH) by using in vivo SAH models. The optimized EGCG-NPs with a Box-Behnken design showed a small particle size of 167 nm, a zeta potential value of -22.6 mV, an encapsulation efficiency of 86%, and a sustained-release profile up to 8 days in vitro. Furthermore, EGCG-NPs (75 mg/kg/d) had superior antioxidative activity to free EGCG (100 mg/kg/d). EGCG-NPs combined with nimodipine exhibited significant synergistic effects against neuronal cell death by suppressing oxidative stress, Ca²⁺ overloading, mitochondrial dysfunction, and autophagy after SAH. These results suggest that cotreatment with EGCG-NPs and nimodipine may serve as a promising novel strategy for the treatment of SAH.

Demonstration of anti-oxidant properties of mustard seed (Brassica juncea) protein isolate in orange juice

Previous research has shown that formulated and natural beverages containing mixtures of anti-oxidants can produce stable levels of hydrogen peroxide (H₂O₂). The aim of this study was to demonstrate the ultimate anti-oxidant effects of proteins for suppressing H₂O₂, using a protein extract from mustard seed (Brassica juncea). The mustard seed protein isolate (MPI) contained ∼51% protein, and 6.4 mg GAe/g TS of total reducible substances, presumably representing secondary metabolites, including polyphenolics. Dose-dependent suppression of H₂O₂ (present at 110 µM and 550 µM), in fresh and thermally-processed orange juice was complete in the presence of 0.1 mg/mL MPI after 24 hr, with slightly higher anti-oxidant efficacy than the fruit juice-derived reference protein, thaumatin. The combination of thiol-rich amino acid (methionine and cysteine)-containing proteins and other anti-oxidant species in the MPI were highly effective for inhibiting autoxidation-mediated production of H₂O₂ in orange juice, and may be useful for other manufactured beverages.

Epigallocatechin Gallate (EGCG) for Parkinson's Disease

In the last couple of decades, we have experienced increased use of nutraceuticals worldwide with a demand for organic foods, which has been elevated to an extent probably unmatched with other periods of our civilization. One of the nutraceuticals that gained attention is epigallocatechin gallate (EGCG), a polyphenol in green tea. It has been suggested that diseases of the central nervous system (CNS) can benefit from consuming some antioxidants, despite current results showing little evidence for their use in preventing and treating these diseases. ECGC may be beneficial in delaying the neurodegeneration of the substantia nigra (SN) regardless of the origin of Parkinson's disease (PD). This review covers the effect of EGCG on vitro and animal models of PD, the potential mechanisms of neuroprotection involved and summaries recent clinical trials in human PD. This review also aims to provide an investigative analysis of the current knowledge in this field and identify putative crucial issues. Environmental factors such as dietary habits, drug use, and social interaction are all factors that influence the evolution of neurodegenerative diseases. Therefore, the use of nutraceuticals requires further investigation. This article is protected by copyright. All rights reserved.

Pro-Oxidant and Cytotoxic Effects of Tucum-Do-Cerrado (Bactris setosa Mart.) Extracts in Colorectal Adenocarcinoma Caco-2 Cells

Colorectal cancer is one of the most common types of cancer. Bioactive natural compounds can act in cancer chemoprevention as tumor growth inhibitors. Tucum-do-cerrado (Bactris setosa Mart.) is a Brazilian fruit that contains several phenolic compounds. This study investigated the effect of tucum aqueous extract in Caco-2 cells in comparison to primary human intestinal organoids and fibroblasts. Cells were exposed to 0.5 and 1 mg/ml of tucum aqueous extract for 24 h. ROS production, mRNA levels for SOD1 and SOD2, CAT, GPX1, NFE2L2, HIF1A and NOS2 were evaluated in Caco-2 cells exposed to tucum extract. Cell viability of Caco-2 cells was decreased upon tucum extract exposure. Mitochondrial ROS levels increased in Caco-2 cells exposed to tucum extract. The mRNA levels of SOD1, SOD2, CAT, GPX, NFE2L2 and HIF1A were downregulated in Caco-2 cells exposed to tucum extract, while NOS2 mRNA levels remained unchanged. Protein levels of SOD2, CAT and NRF2 remained unchanged in Caco-2 cells treated with tucum extract, indicating that catalase and SOD2 cellular functions may be unaffected by the tucum extract at 24 h, of exposure. Aqueous extract of tucum-do-cerrado may induce cellular toxicity in a cancer cell-specific manner, possibly through increased mitochondrial ROS production and gene expression regulation.

Effects of Hydrogen Peroxide Produced by Catechins on the Aroma of Tea Beverages

Hydrogen peroxide has a significant effect on the flavor of tea beverages. In this study, the yield of hydrogen peroxide in (-)-epigallocatechin gallate (EGCG) solution was first investigated and found to be significantly enhanced under specific conditions, and the above phenomenon was amplified by the addition of linalool. Then, an aqueous hydrogen peroxide solution was added to a linalool solution and it was found that the concentration of linalool was significantly reduced in the above-reconstituted system. These findings were verified by extending the study system to the whole green tea infusions. The results suggested that the production of hydrogen peroxide in tea beverages may be dominated by catechins, with multiple factors acting synergistically, thereby leading to aroma deterioration and affecting the quality of tea beverages. The above results provided a feasible explanation for the deterioration of flavor quality of green tea beverages with shelf life.

Vascular Protective Effect and Its Possible Mechanism of Action on Selected Active Phytocompounds: A Review

Vascular endothelial dysfunction is characterized by an imbalance of vasodilation and vasoconstriction, deficiency of nitric oxide (NO) bioavailability and elevated reactive oxygen species (ROS), and proinflammatory factors. This dysfunction is a key to the early pathological development of major cardiovascular diseases including hypertension, atherosclerosis, and diabetes. Therefore, modulation of the vascular endothelium is considered an important therapeutic strategy to maintain the health of the cardiovascular system. Epidemiological studies have shown that regular consumption of medicinal plants, fruits, and vegetables promotes vascular health, lowering the risk of cardiovascular diseases. This is mainly attributed to the phytochemical compounds contained in these resources. Various databases, including Google Scholar, MEDLINE, PubMed, and the Directory of Open Access Journals, were searched to identify studies demonstrating the vascular protective effects of phytochemical compounds. The literature had revealed abundant data on phytochemical compounds protecting and improving the vascular system. Of the numerous compounds reported, curcumin, resveratrol, cyanidin-3-glucoside, berberine, epigallocatechin-3-gallate, and quercetin are discussed in this review to provide recent information on their vascular protective mechanisms in vivo and in vitro. Phytochemical compounds are promising therapeutic agents for vascular dysfunction due to their antioxidative mechanisms. However, future human studies will be necessary to confirm the clinical effects of these vascular protective mechanisms.

Epigallocatechin 3-gallate: From green tea to cancer therapeutics

Epigallocatechin 3-gallate (EGCG) possesses various biological functions, including anti-cancer and anti-inflammatory properties. EGCG is an abundant polyphenolic component originating from green tea extract that has exhibited versatile bioactivities in combating several cancers. This review highlights the pharmacological features of EGCG and its therapeutic implications in cancer and other metabolic diseases. It modulates numerous signaling pathways, regulating cells' undesired survival and proliferation, thus imparting strong tumor chemopreventive and therapeutic effects. EGCG initiates cell death through the intrinsic pathway and causes inhibition of EGFR, STAT3, and ERK pathways in several cancers. EGCG alters and inhibits ERK1/2, NF-κB, and Akt-mediated signaling, altering the Bcl-2 family proteins ratio and activating caspases in tumor cells. This review focuses on anti-cancer, anti-oxidant, anti-inflammatory, anti-angiogenesis, and apoptotic effects of EGCG. We further highlighted the potential of EGCG in different types of cancer, emphasizing clinical trials formulations that further improve our understanding of the therapeutic management of cancer and inflammatory diseases.

Neuroprotective Role of Polyphenols in Treatment of Neurological Disorders: A Review

: The most frequent illnesses characterized by the gradual malfunctioning of brain neurons are neurodegenerative disorders (NDs). Genetic mutations and a range of biological processes can produce NDs. Alzheimer's disease (AD), Parkinson's disease (PD), and Multiple Sclerosis (MS) are all related to oxidative stress (OS). Reduced brain activity has become a greater health threat with a growing elderly population. It causes some pathophysiological alterations and is an important risk factor for a range of neurodegenerative illnesses. An increase in reactive oxygen species (ROS) can cause neuronal cell death, and it is thus essential to control ROS levels to maintain normal neuronal activity. Synthetic medicines are often used to treat neurological disorders; however, harmful effects have been reported. Multiple bodies of research have shown the effectiveness of polyphenols in the treatment of various NDs due to their negligible side effects. This review article describes the neuroprotection effects of polyphenols such as resveratrol, epigallocatechin-3-gallate, curcumin, and quercetin, as well as the signaling pathways and immune response controls through polyphenols.

Prenatal EGCG exposure-induced heart mass reduction in adult male mice and underlying mechanisms

Epigallocatechin-3-gallate (EGCG), which is a major polyphenol in tea, has an unclear effect on cardiac development. In the present study, mice (C57BL/6) were exposed in utero to EGCG dissolved in drinking water (3 μg/ml) for 16 days. A significant decrease in the heart/body weight ratio was observed in adult males but not in adult females. The protein expression levels of TGF-β1 and its downstream transcription factors SMAD3 and SMAD4 were significantly decreased in male hearts. The PI3K/AKT signaling pathway was inhibited, the expression of proapoptotic proteins, such as BAX, Cleaved Caspase3 and Cleaved Caspase9, was elevated, and the level of antiapoptotic proteins, such as BCL-2, was decreased. A reduced heart/body weight ratio may be associated with the loss of cardiac fibers and an increase in myocardial apoptosis. The cardiac levels of aromatic hydrocarbon receptor and androgen receptor were elevated only in males, which may explain the sexual dimorphism in the effects. The promoter methylation levels of pik3r1, tgf-β, smad4 were elevated, and those of ahr were reduced, explaining the mechanism underlying the cardiac histological alteration caused by prenatal exposure to EGCG. The results suggest that ingestion of EGCG during pregnancy may be a risk factor for cardiac development in offspring.

Metabolic Implications of Oxidative Stress and Inflammatory Process in SARS-CoV-2 Pathogenesis: Therapeutic Potential of Natural Antioxidants

COVID-19 is a zoonotic disease with devastating economic and public health impacts globally. Being a novel disease, current research is focused on a clearer understanding of the mechanisms involved in its pathogenesis and viable therapeutic strategies. Oxidative stress and inflammation are intertwined processes that play roles in disease progression and response to therapy via interference with multiple signaling pathways. The redox status of a host cell is an important factor in viral entry due to the unique conditions required for the conformational changes that ensure the binding and entry of a virus into the host cell. Upon entry into the airways, viral replication occurs and the innate immune system responds by activating macrophage and dendritic cells which contribute to inflammation. This review examines available literature and proposes mechanisms by which oxidative stress and inflammation could contribute to COVID-19 pathogenesis. Further, certain antioxidants currently undergoing some form of trial in COVID-19 patients and the corresponding required research gaps are highlighted to show how targeting oxidative stress and inflammation could ameliorate COVID-19 severity.

Epigallocatechin Gallate for Management of Heavy Metal-Induced Oxidative Stress: Mechanisms of Action, Efficacy, and Concerns

In this review, we highlight the effects of epigallocatechin gallate (EGCG) against toxicities induced by heavy metals (HMs). This most active green tea polyphenol was demonstrated to reduce HM toxicity in such cells and tissues as testis, liver, kidney, and neural cells. Several protective mechanisms that seem to play a pivotal role in EGCG-induced effects, including reactive oxygen species scavenging, HM chelation, activation of nuclear factor erythroid 2-related factor 2 (Nrf2), anti-inflammatory effects, and protection of mitochondria, are described. However, some studies, especially in vitro experiments, reported potentiation of harmful HM actions in the presence of EGCG. The adverse impact of EGCG on HM toxicity may be explained by such events as autooxidation of EGCG, EGCG-mediated iron (Fe3+) reduction, depletion of intracellular glutathione (GSH) levels, and disruption of mitochondrial functions. Furthermore, challenges hampering the potential EGCG application related to its low bioavailability and proper dosing are also discussed. Overall, in this review, we point out insights into mechanisms that might account for both the beneficial and adverse effects of EGCG in HM poisoning, which may have a bearing on the design of new therapeutics for HM intoxication therapy.

Anticancer activity of flavonoids accompanied by redox state modulation and the potential for a chemotherapeutic strategy

Since researchers began studying the mechanism of flavonoids' anticancer activity, little attention has been focused on the modulation of redox state in cells as a potential chemotherapeutic strategy. However, recent studies have begun identifying that the anticancer effect of flavonoids occurs both in their antioxidative activity which scavenges ROS and their prooxidative activity which generates ROS. Against this backdrop, this study attempts to achieve a comprehensive analysis of the individual and separate study findings regarding flavonoids' modulation of redox state in cancer cells. It focuses on the mechanism behind the anticancer effect, and mostly on the modulation of redox potential by flavonoids such as quercetin, hesperetin, apigenin, genistein, epigallocatechin-3-gallate (EGCG), luteolin and kaempferol in both in vitro and animal models. In addition, the clinical applications of and bioavailability of flavonoids were reviewed to help build a treatment strategy based on flavonoids' prooxidative potential.

Mitoapocynin, a mitochondria targeted derivative of apocynin induces mitochondrial ROS generation and apoptosis in multiple cell types including cardiac myoblasts: a potential constraint to its therapeutic use

Mitoapocynin is a triphenylphosphonium conjugated derivative of apocynin that specifically locates to the mitochondria. It has been developed as a mitochondrially targeted therapeutic antioxidant. We attempted to attenuate the mitochondrial ROS induced in H9c2 cardiac myoblast cells treated with norepinephrine. Mitoapocynin was a poor quencher of total ROS as detected by the fluoroprobe DCFH-DA. Using mitochondrial superoxide specific probe MitoSoxRed, we found that 5-10 µM mitoapocynin itself induces superoxide over and above that is generated by the norepinephrine treatment. A supposedly control molecule to mitoapocynin, the synthetic compound PhC11TPP, having the triphenylphosphonium group and a benzene moiety with C11 aliphatic chain spacer was also found to be a robust inducer of mitochondrial ROS. Subsequent assays with several cell lines viz., NIH3T3, HEK293, Neuro2A, MCF-7 and H9c2, showed that prolonged exposure to mitoapocynin induces cell death by apoptosis that can be partially prevented by the general antioxidant N-acetyl cysteine. Analyses of mitochondrial electron transport complexes by Blue Native Polyacrylamide gel electrophoresis showed that both mitoapocynin and PhC11TPP disrupt the mitochondrial Complex I and V, and in addition, PhC11TPP also damages the Complex IV. Our data thus highlights the limitations of the therapeutic use of mitoapocynin as an antioxidant.

Yellow gentian root extract provokes concentration- and time-dependent response in peripheral blood mononuclear cells

Yellow gentian (Gentiana lutea L.), a medicinal plant widely used in traditional medicine, displays multiple biological effects, ranging from beneficial to toxic. Since many promising applications have been reported so far, our aim was to evaluate its potential concentration- and time- dependent cytotoxic and genotoxic effects in vitro. To that end we exposed human peripheral blood mononuclear cells to 0.5, 1, and 2 mg/mL of yellow gentian root extract (YGRE) to determine its effects on oxidative stress parameters [pro/antioxidant balance (PAB) and lipid peroxidation], DNA damage (alkaline comet assay and chromosome aberrations), and cell viability (trypan blue exclusion test). Cell viability decreased with increasing concentrations and treatment duration. Only the lowest YGRE concentration (0.5 mg/mL) increased oxidative stress but produced minor DNA damage and cytotoxicity. At higher concentrations, redox parameters returned to near control values. The percentage of chromosome aberrations and percentage of DNA in the comet tail increased with increased YGRE concentration after 48 h and declined after 72 h of treatment. This points to the activation of DNA repair mechanism (homologous recombination), evidenced by the formation of chromosomal radial figures after 72 h of treatment with the highest YGRE concentration of 2 mg/mL. Our results suggest that YGRE, despite induction of cytotoxic and genotoxic effects, activates cell repair mechanisms that counter oxidative and DNA lesions and induce cell death in highly damaged cells. Therefore, observed protective effects of yellow gentian after longer exposure could be a result of activated repair and removal of cells with irreparable damage.

Arsenal of Phytochemicals to Combat Against Arsenic-Induced Mitochondrial Stress and Cancer

Significance: Phytochemicals are important dietary constituents with antioxidant properties. They affect various signaling pathways involved in the overall maintenance of interior milieu of the cell. Arsenic, an environmental toxicant, is well known for its deleterious consequences, such as various diseases, including cancers in humans. Mitochondria are the cell's powerhouse that fuel all metabolic energy requirements. Dysfunctional mitochondria due to stressors may lead to abnormal functioning of the organelle, hampering the crucial cellular cross talks and ultimately leading to cancer. Application of phytochemicals against arsenic-induced mitochondrial disorders may be a preventive measure to counteract the ruinous impacts of the metalloid. Recent Advances: In recent years, extensive research on the role of mitochondria in cancer gives a better understanding of the areas the organelle covers in maintaining a healthy cell or in inducing carcinogenicity. Detailed knowledge of the mitochondrial governances would enable researchers to administer numerous phytochemicals to ameliorate altered oxidative phosphorylation, mitochondrial membrane potential (MMP), mitochondrial oxidative stress, unfolded protein response, glycolysis, or even apoptosis. Critical Issues: In this review, we have addressed how various phytochemicals belonging to diverse classes combat against arsenic-induced mitochondrial oxidative stress, depletion of MMP, cell cycle abrogation, apoptosis, glycolytic damages, oncogenic regulations, chaperones, mitochondrial complexes, and mitochondrial membrane pore formation in both in vitro and in vivo models. Future Directions: Insightful application of mitoprotective phytochemicals against arsenic-induced mitochondrial oxidative stress and carcinogenesis may guide researchers to develop preclinical chemopreventive agents to fight arsenic toxicity in humans.

Identification and in vitro anti-inflammatory activity of different forms of phenolic compounds in Camellia oleifera oil

Camellia oleifera (C. oleifera) oil is known as "oriental olive oil". We previously reported the anti-inflammatory activity of C. oleifera oil was mainly attributed to the phenolic compounds, but the specific compounds remain uncovered. In this study, phenolic compounds in the form of free (11.92 μg GAE/g), esterified (37.57 μg GAE/g), glycosylated (128.71 μg GAE/g), and insoluble (47.53 μg GAE/g) were prepared from C. oleifera oil. Their anti-inflammatory activities were evaluated by lipopolysaccharide induced RAW 264.7 macrophage. Glycosylated fraction showed the highest anti-inflammatory activity as indicated by the low production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Subsequently, 13 different glycosylated polyphenols were identified by UPLC-Q-TOF/MS, and the major compounds were purified for anti-inflammatory re-evaluation. Lower anti-inflammatory activities of compound 3 and compound 6 were observed when compared to kaempferol. Overall, these results would promote the utilization of phenolic compounds in C. oleifera oil.

Oregano Phytocomplex Induces Programmed Cell Death in Melanoma Lines via Mitochondria and DNA Damage

Plant secondary metabolites possess chemopreventive and antineoplastic properties, but the lack of information about their exact mechanism of action in mammalian cells hinders the translation of these compounds in suitable therapies. In light of this, firstly, Origanum vulgare L. hydroalcoholic extract was chemically characterized by spectrophotometric and chromatographic analyses; then, the molecular bases underlying its antitumor activity on B16-F10 and A375 melanoma cells were investigated. Oregano extract induced oxidative stress and inhibited melanogenesis and tumor cell proliferation, triggering programmed cell death pathways (both apoptosis and necroptosis) through mitochondria and DNA damage. By contrast, oregano extract was safe on healthy tissues, revealing no cytotoxicity and mutagenicity on C2C12 myoblasts, considered as non-tumor proliferating cell model system, and on Salmonella strains, by the Ames test. All these data provide scientific evidence about the potential application of this food plant as an anticancer agent in in vivo studies and clinical trials.

Distinct phenolic, alkaloid and antioxidant profile in betel quids from four regions of Indonesia

Betel quid (BQ) is a chewing mixed package that mainly contains areca nut (AN), betel leaf (Leaf) or betel stem inflorescence (SI), and slaked lime, and is consumed with or without tobacco BQ chewing is common in South East Asia and has been strongly associated with malignant and potentially malignant diseases of the oral cavity. Alkaloids such as arecoline are often accounted for the carcinogenic potential of BQ, however the chemical composition of BQ has not been studied in detail. In the current study, we investigated the total phenolic content (TPC), antioxidant activity (by mean of ferric reducing antioxidant power, FRAP), radical scavenging activity (DPPH test), polyphenolic profile and arecoline content in different components of BQ, namely AN, Leaf or SI, Husk, and blended BQ (BQ mix, containing AN, Leaf or SI and slaked lime). Samples were imported from 4 major regions of Indonesia, namely: Banda Aceh (BA), North Sumatra (NS), West Kalimantan (WK) and West Papua (WP). The highest TPC, FRAP, and DPPH values were detected in AN samples compared to other BQ components, while samples from WP region were of higher values compared to the other regions. High performance liquid chromatography—Mass Spectrometry (LC–MS) analysis showed that Husk contains the widest range of polyphenols, including hydroxybenzoic acids, hydroxycinnamic acids, flavanols, flavonols and stilbenes. Catechin and epicatechin were the main polyphenols detected in BQ, and they were present at the highest concentrations in WP–AN sample. Arecoline was detected in all AN and BQ mix samples and was significantly correlated with catechin and epicatechin, and significantly negatively correlated with p-hydroxybenzoic acid. Notably, arecoline concentration changed significantly when AN was blended in BQ mixtures. The current study is the first to extensively characterise the chemical composition of BQ and provides insight for a better understanding of the interactions of BQ alkaloids and phenolics in the development of oral submucous fibrosis and oral cancer.

Small molecules regulating reactive oxygen species homeostasis for cancer therapy

Elevated intracellular reactive oxygen species (ROS) and antioxidant defense systems have been recognized as one of the hallmarks of cancer cells. Compared with normal cells, cancer cells exhibit increased ROS to maintain their malignant phenotypes and are more dependent on the "redox adaptation" mechanism. Thus, there are two apparently contradictory but virtually complementary therapeutic strategies for the regulation of ROS to prevent or treat cancer. The first strategy, that is, chemoprevention, is to prevent or reduce intracellular ROS either by suppressing ROS production pathways or by employing antioxidants to enhance ROS clearance, which protects normal cells from malignant transformation and inhibits the early stage of tumorigenesis. The second strategy is the ROS-mediated anticancer therapy, which stimulates intracellular ROS to a toxicity threshold to activate ROS-induced cell death pathways. Therefore, targeting the regulation of intracellular ROS-related pathways by small-molecule candidates is considered to be a promising treatment for tumors. We herein first briefly introduce the source and regulation of ROS, and then focus on small molecules that regulate ROS-related pathways and show efficacy in cancer therapy from the perspective of pharmacophores. Finally, we discuss several challenges in developing cancer therapeutic agents based on ROS regulation and propose the direction of future development.

Green tea polyphenolic antioxidants oxidize hydrogen sulfide to thiosulfate and polysulfides: A possible new mechanism underpinning their biological action

Matcha and green tea catechins such as (−)-epicatechin (EC), (−)-epigallocatechin (EGC) and (−)-epigallocatechin gallate (EGCG) have long been studied for their antioxidant and health-promoting effects. Using specific fluorophores for H₂S (AzMC) and polysulfides (SSP4) as well as IC-MS and UPLC-MS/MS-based techniques we here show that popular Japanese and Chinese green teas and select catechins all catalytically oxidize hydrogen sulfide (H₂S) to polysulfides with the potency of EGC > EGCG >> EG. This reaction is accompanied by the formation of sulfite, thiosulfate and sulfate, consumes oxygen and is partially inhibited by the superoxide scavenger, tempol, and superoxide dismutase but not mannitol, trolox, DMPO, or the iron chelator, desferrioxamine. We propose that the reaction proceeds via a one-electron autoxidation process during which one of the OH-groups of the catechin B-ring is autooxidized to a semiquinone radical and oxygen is reduced to superoxide, either of which can then oxidize HS⁻ to thiyl radicals (HS^•) which react to form hydrogen persulfide (H₂S₂). H₂S oxidation reduces the B-ring back to the hydroquinone for recycling while the superoxide is reduced to hydrogen peroxide (H₂O₂). Matcha and catechins also concentration-dependently and rapidly produce polysulfides in HEK293 cells with the potency order EGCG > EGC > EG, an EGCG threshold of ~300 nM, and an EC₅₀ of ~3 μM, suggesting green tea also acts as powerful pro-oxidant in vivo. The resultant polysulfides formed are not only potent antioxidants, but elicit a cascade of secondary cytoprotective effects, and we propose that many of the health benefits of green tea are mediated through these reactions. Remarkably, all green tea leaves constitutively contain small amounts of H₂S₂.

Production of hydrogen peroxide in formulated beverages is associated with the presence of ascorbic acid combined with selected redox-active functional ingredients

Hydrogen peroxide (H₂O₂) is a reactive oxygen species (ROS) that mediates essential signaling in vivo but may cause irreversible tissue damage under dysregulated or acute exposure conditions. Beverages containing redox-active compounds might produce H₂O₂ during shelf storage and potentially be consumed. Concentrations of H₂O₂ in selected 'functional' (including energy, E, n = 28), 'non-functional' flavored, (S, n = 6) and mineral water (W, n = 6) drinks were measured under ambient (i.e., produced in situ) and 'potentiated' conditions (i.e., H₂O₂ production enhanced by addition of a reducing agent, to simulate availability of reducible substrates in vivo). Under air-saturated conditions, mean H₂O₂ contents were: 15.60 ± 15.84; 1.39 ± 2.06 and 0.30 ± 0.21 µM in E, S and W drinks, respectively. Under air-saturated, potentiated conditions, mean rates of H₂O₂ production were 21.7 ± 33.3, 0.98 ± 2.84, and -0.38 ± 1.18 µM/h for E, S and W drinks, respectively. Using multivariate statistics, the ingredient significantly associated with H₂O₂ production in combination with other ingredients was found to be ascorbic acid.

Targeting apoptosis and autophagy following spinal cord injury: Therapeutic approaches to polyphenols and candidate phytochemicals

Spinal cord injury (SCI) is a neurological disorder associated with the loss of sensory and motor function. Understanding the precise dysregulated signaling pathways, especially apoptosis and autophagy following SCI, is of vital importance in developing innovative therapeutic targets and treatments. The present study lies in the fact that it reveals the precise dysregulated signaling mediators of apoptotic and autophagic pathways following SCI and also examines the effects of polyphenols and other candidate phytochemicals. It provides new insights to develop new treatments for post-SCI complications. Accordingly, a comprehensive review was conducted using electronic databases including, Scopus, Web of Science, PubMed, and Medline, along with the authors' expertise in apoptosis and autophagy as well as their knowledge about the effects of polyphenols and other phytochemicals on SCI pathogenesis. The primary mechanical injury to spinal cord is followed by a secondary cascade of apoptosis and autophagy that play critical roles during SCI. In terms of pharmacological mechanisms, caspases, Bax/Bcl-2, TNF-α, and JAK/STAT in apoptosis along with LC3 and Beclin-1 in autophagy have shown a close interconnection with the inflammatory pathways mainly glutamatergic, PI3K/Akt/mTOR, ERK/MAPK, and other cross-linked mediators. Besides, apoptotic pathways have been shown to regulate autophagy mediators and vice versa. Prevailing evidence has highlighted the importance of modulating these signaling mediators/pathways by polyphenols and other candidate phytochemicals post-SCI. The present review provides dysregulated signaling mediators and therapeutic targets of apoptotic and autophagic pathways following SCI, focusing on the modulatory effects of polyphenols and other potential phytochemical candidates.

The Intrinsic Virtues of EGCG, an Extremely Good Cell Guardian, on Prevention and Treatment of Diabesity Complications

The pandemic proportion of diabesity—a combination of obesity and diabetes—sets a worldwide health issue. Experimental and clinical studies have progressively reinforced the pioneering epidemiological observation of an inverse relationship between consumption of polyphenol-rich nutraceutical agents and mortality from cardiovascular and metabolic diseases. With chemical identification of epigallocatechin-3-gallate (EGCG) as the most abundant catechin of green tea, a number of cellular and molecular mechanisms underlying the activities of this unique catechin have been proposed. Favorable effects of EGCG have been initially attributed to its scavenging effects on free radicals, inhibition of ROS-generating mechanisms and upregulation of antioxidant enzymes. Biologic actions of EGCG are concentration-dependent and under certain conditions EGCG may exert pro-oxidant activities, including generation of free radicals. The discovery of 67-kDa laminin as potential EGCG membrane target has broaden the likelihood that EGCG may function not only because of its highly reactive nature, but also via receptor-mediated activation of multiple signaling pathways involved in cell proliferation, angiogenesis and apoptosis. Finally, by acting as epigenetic modulator of DNA methylation and chromatin remodeling, EGCG may alter gene expression and modify miRNA activities. Despite unceasing research providing detailed insights, ECGC composite activities are still not completely understood. This review summarizes the most recent evidence on molecular mechanisms by which EGCG may activate signal transduction pathways, regulate transcription factors or promote epigenetic changes that may contribute to prevent pathologic processes involved in diabesity and its cardiovascular complications.

DNA damage and DNA protection from digested raw and griddled green pepper (poly)phenols in human colorectal adenocarcinoma cells (HT-29)

PURPOSE

To determine whether (poly)phenols from gastrointestinal-digested green pepper possess genoprotective properties in human colon cells and whether the application of a culinary treatment (griddling) on the vegetable influences the potential genoprotective activity.

METHODS

(Poly)phenols of raw and griddled green pepper (Capsicum annuum L.) submitted to in vitro-simulated gastrointestinal digestion were characterized by LC-MS/MS. Cytotoxicity (MTT, trypan blue and cell proliferation assays), DNA damage and DNA protection (standard alkaline and formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay) of different concentrations of (poly)phenolic extracts were assessed in colon HT-29 cells.

RESULTS

A total of 32 (poly)phenolic compounds were identified and quantified in digested raw and griddled green pepper. Twenty of them were flavonoids and 12 were phenolic acids. Griddled pepper doubled the (poly)phenol concentration compared to raw; luteolin 7-O-(2-apiosyl)-glucoside and quercitrin constituted the major (poly)phenols in both extracts. Raw and griddled pepper (poly)phenolic extracts impaired cell proliferation and induced low levels of Fpg-sensitive sites, in a dose-dependent manner, even at a non-cytotoxic concentration. None of the concentrations tested induced DNA strand breaks or alkaline labile sites. Nor did they show significant genoprotection against the DNA damage induced by H₂O₂ or KBrO₃.

CONCLUSIONS

Green pepper (poly)phenols did not show genoprotection against oxidatively generated damage in HT-29 cells at simulated physiological concentrations, regardless of the application, or not, of a culinary treatment (griddling). Furthermore, high concentrations of (poly)phenolic extracts induced a slight pro-oxidant effect, even at a non-cytotoxic concentration.

Epigallocatechin-3-Gallate Toxicity in Children: A Potential and Current Toxicological Event in the Differential Diagnosis With Virus-Triggered Fulminant Hepatic Failure

The use of nutraceuticals is considerably increasing worldwide with a demand for organic and clean foods in the last two decades, which is probably incomparable with other periods of our civilization. The consistent application of nutraceuticals and so-called "superfood" may have remarkable effects on the prevention of several chronic diseases, including cancer. Moreover, the increased rate of overweight and obesity in Western countries does not spare childhood and youth, and the number of parents using natural remedies for preventing pediatric illness is vastly increasing worldwide. However, the overwhelming effects on diseases often overshadow the side effects of such nutrition, particularly in societies without millennial experience with botanicals and natural elements. Thus, the final result may be disastrous for some individuals. The liver is the most important and conspicuous target organ of numerous molecular compounds, and the cell damage is particularly striking on the infantile and pediatric liver due to the immaturity of the hepatocytes. Here, we target some generic data on fulminant hepatic failure, the benefits, and toxicity of epigallocatechin-3-gallate, which is one of the major components of green tea, and the histopathology of the "green-tea"-associated liver disease.

Polyphenol Characterization and Skin-Preserving Properties of Hydroalcoholic Flower Extract from Himantoglossum robertianum (Orchidaceae)

Himantoglossum robertianum (Loisel.) P. Delforge is a Mediterranean orchid whose propagation in vitro has been achieved, making it eligible as a source of bioactive substances. Flowers were analyzed by light and SEM microscopy and used to obtain a polyphenol-rich, hydroalcoholic flower extract (HFE). HFE was characterized for total phenols, flavonoids and proanthocyanidins, and for polyphenol profile by RP-LC-DAD. Antioxidant assays, in vitro collagenase and elastase inhibition, and MTT and cell motility assays on HaCaT keratinocytes were done. Microscopy showed epidermal cells containing anthocyanins in the flower labellum. Flavonoids (flavones and flavan-3-ols) represented the most abundant compounds (42.91%), followed by scopoletin (33.79%), and phenolic acids (23.3%). Antioxidant assays showed strong activities, rating ORAC > FRAP > TEAC > β-carotene bleaching > DPPH > iron-chelation. Biological assays showed elastase and collagenase inhibition (up to 42% and 78%, respectively), improvement of HaCaT cell viability after treatment with 500 μM H₂O₂ (from 30% to 84% of control), and stimulation of cell migration rate up to 210% of control. In summary, HFE counteracted different free radicals, while protective properties were shown by cell-free and cell-based bioassays, suggesting the possible use of H. robertianum flowers for skin-preserving, repair, and anti-aging applications.

Epigallocatechin-3-gallate induces telomere shortening and clastogenic damage in glioblastoma cells

Epigallocatechingallate (EGCG) is the major polyphenol in green tea, to which many anticancer features, such as antioxidative, antigenotoxic, and antiangiogenetic properties, are attributed. Moreover, it is also well known as a telomerase inhibitor. In this work, we have chronically treated U251 glioblastoma cells with low, physiologically realistic concentrations, of EGCG, in order to investigate its effects both on telomeres and on genome integrity. Inhibition of telomerase activity caused telomere shortening, ultimately leading to senescence and telomere dysfunction at 98 days. Remarkably, we have observed DNA damage through an increase of phosphorylation of γ-H2AX histone and micronuclei also with doses and at timepoints when telomere shortening was not present. Therefore, we concluded that this DNA damage was not correlated with telomere shortening and that EGCG treatment induced not only an increase of telomere-shortening-induced senescence but also telomere-independent genotoxicity. This study questions the common knowledge about EGCG properties, but confirms the few works that indicated the clastogenic properties of this molecule, probably due to DNA reductive damage and topoisomerase II poisoning. Environ. Mol. Mutagen., 60:683-692, 2019. © 2019 Wiley Periodicals, Inc.

Polyphenols: Immunomodulatory and Therapeutic Implication in Colorectal Cancer

Polyphenolic compounds, widely present in fruits, vegetables, and cereals, have potential benefits for human health and are protective agents against the development of chronic/degenerative diseases including cancer. More recently these bioactive molecules have been gaining great interest as anti-inflammatory and immunomodulatory agents, mainly in neoplasia where the pro-inflammatory context might promote carcinogenesis. Colorectal cancer (CRC) is considered a major public healthy issue, a leading cause of cancer mortality and morbidity worldwide. Epidemiological, pre-clinical and clinical investigations have consistently highlighted important relationships between large bowel inflammation, gut microbiota (GM), and colon carcinogenesis. Many experimental studies and clinical evidence suggest that polyphenols have a relevant role in CRC chemoprevention, exhibit cytotoxic capability vs. CRC cells and induce increased sensitization to chemo/radiotherapies. These effects are most likely related to the immunomodulatory properties of polyphenols able to modulate cytokine and chemokine production and activation of immune cells. In this review we summarize recent advancements on immunomodulatory activities of polyphenols and their ability to counteract the inflammatory tumor microenvironment. We focus on potential role of natural polyphenols in increasing the cell sensitivity to colon cancer therapies, highlighting the polyphenol-based combined treatments as innovative immunomodulatory strategies to inhibit the growth of CRC.

Surface tethering of stem cells with H2O2-responsive anti-oxidizing colloidal particles for protection against oxidation-induced death

Mesenchymal stem cells are the new generation of medicine for treating numerous vascular diseases and tissue defects because of their ability to secrete therapeutic factors. Poor cellular survival in an oxidative diseased tissue, however, hinders the therapeutic efficacy. To this end, we hypothesized that tethering the surface of stem cells with colloidal particles capable of discharging antioxidant cargos in response to elevated levels of hydrogen peroxide (H₂O₂) would maintain survival and therapeutic activity of the stem cells. We examined this hypothesis by encapsulating epigallocatechin gallate (EGCG) and manganese oxide (MnO₂) nanocatalysts into particles comprising poly(d,l-lactide-co-glycolide)-block-hyaluronic acid. The MnO₂ nanocatalysts catalyzed the decomposition of H₂O₂ into oxygen gas, which increased the internal pressure of particles and accelerated the release of EGCG by 1.5-fold. Consequently, stem cells exhibited 1.2-fold higher metabolic activity and 2.8-fold higher secretion level of pro-angiogenic factor in sub-lethal H₂O₂ concentrations. These stem cells, in turn, performed a greater angiogenic potential with doubled number of newly formed mature blood vessels. We envisage that the results of this study will contribute to improving the therapeutic efficacy of a wide array of stem cells.

Protein-Protected Gold Nanocluster-Based Biosensor for Determining the Prooxidant Activity of Natural Antioxidant Compounds

In this work, chicken egg white protein (CEW)-protected gold nanoclusters (CEW-AuNCs) were prepared from CEW and HAuCl4 to measure the Cu(II)-induced prooxidant activity of antioxidant compounds such as epicatechin, epigallocatechin gallate, catechin, rosmarinic acid, resveratrol, ascorbic acid, and glutathione. These compounds reduced Cu(II) to Cu(I), and the latter was mainly bound to thiol groups in the CEW-AuNC structure. As the protein-bound Cu(I) may act as a catalytic center for generating reactive oxygen species, the Cu(II) reducing ability of antioxidants is an indirect measure of their prooxidant potency. The bound Cu(I) may be released with the cuprous-selective ligand neocuproine (Nc), forming the basis of a spectrophotometric method measuring absorbance at 450 nm wavelength of the Cu(I)-Nc chelate. The developed method involved a one-pot synthesis and determination without preseparation and was applied to binary synthetic mixtures of studied antioxidant compounds and to certain herbal plant (green tea, linden, echinacea, and artichoke leaf) extracts to determine the total prooxidant activities. The obtained results were statistically compared with those of the literature Cu(II)-Nc assay using a calcium proteinate-based solid biosensor. The developed biosensor was durable, reliable, easily applicable, and of low cost and wide linear range and could determine the prooxidant activities of natural antioxidant samples with high reproducibility.

Effects and Underlying Mechanisms of Bioactive Compounds on Type 2 Diabetes Mellitus and Alzheimer's Disease

Type 2 diabetes mellitus is a complicated metabolic disorder characterized by hyperglycemia and glucose intolerance. Alzheimer's disease is a progressive brain disorder characterized by a chronic loss of cognitive and behavioral function. Considering the shared characteristics of both diseases, common therapeutic and preventive agents may be effective. Bioactive compounds such as polyphenols, vitamins, and carotenoids found in vegetables and fruits can have antioxidant and anti-inflammatory effects. These effects make them suitable candidates for the prevention or treatment of diabetes and Alzheimer's disease. Increasing evidence from cell or animal models suggest that bioactive compounds may have direct effects on decreasing hyperglycemia, enhancing insulin secretion, and preventing formation of amyloid plaques. The possible underlying molecular mechanisms are described in this review. More studies are needed to establish the clinical effects of bioactive compounds.

Diverse Effects of Different "Protein-Based" Vehicles on the Stability and Bioavailability of Curcumin: Spectroscopic Evaluation of the Antioxidant Activity and Cytotoxicity In Vitro

BACKGROUND

Curcumin is a natural polyphenolic compound with anti-cancer, antiinflammatory, and anti-oxidation properties. Low water solubility and rapid hydrolytic degradation are two challenges limiting use of curcumin.

OBJECTIVE

In this study, the roles of the native/modified forms of Bovine Serum Albumin (BSA), β-lactoglobulin (β-lg) and casein, as food-grade biopolymers and also protein chemical modification, in stabilizing and on biological activity of curcumin were surveyed.

METHODS

In this article, we used various spectroscopic as well as cell culture-based techniques along with calculation of thermodynamic parameters.

RESULTS

Investigation of curcumin stability indicated that curcumin binding to the native BSA and modified β -lg were stronger than those of the modified BSA and native β -lg, respectively and hence, the native BSA and modified β-lg could suppress water-mediated and light-mediated curcumin degradation, significantly. Moreover, in the presence of the native proteins (BSA and casein), curcumin revealed elevated in vitro anti-cancer activity against MCF-7 (human breast carcinoma cell line) and SKNMC (human neuroblastoma cell line). As well, curcumin, in the presence of the unmodified "BSA and β-lg", was more potent to decrease ROS generation by hydrogen peroxide (H2O2) whereas it led to an inverse outcome in the presence of native casein. Overall, in the presence of the protein-bound curcumin, increased anti-cancer activity and decreased ROS generation by H2O2 in vitro were documented.

CONCLUSION

It appears that "water exclusion" is major determinant factor for increased stability/ efficacy of the bound curcumin so that some protein-curcumin systems may provide novel tools to increase both food quality and the bioavailability of curcumin as health promoting agent.

Epigallocatechin gallate attenuates mitochondrial DNA-induced inflammatory damage in the development of ventilator-induced lung injury

OBJECTIVE

We aim to investigate the role of mitochondrial DNA (mtDNA), a novel endogenous pro-inflammatory cytokine, in the development of ventilator-induced lung injury (VILI). Moreover, the protective effect of epigallocatechin gallate (EGCG) on VILI through inhibiting local mtDNA release was examined.

METHODS

From March 2015 to March 2016, bronchoalveolar lavage fluid (BALF) from 36 patients with VILI and well-matched 36 patients without VILI after major surgery were consecutively collected. The expression levels of mtDNA and inflammatory cytokines in BALF were tested. SD rats were divided into five groups: control, low tidal volume (7 ml/kg) group, high tidal volume (HTV, 40 ml/kg) group, HTV+low dose EGCG and HTV+high dose EGCG groups. BALF were collected to examine the expression levels of mtDNA and several inflammatory cytokines and the lung tissue was harvested for pathological examinations. In addition, cyclic stretch cell culture was used and culture media was collected to analyze expressions of inflammatory cytokines. Administration of mtDNA in a rat model and in vitro cell culturing were used to confirm its pro-inflammatory properties in the development of inflammatory lung injury.

RESULTS

A Significant elevation of mtDNA was detected in BALF from patients with VILI (581 ± 193 vs. 311 ± 137, p < 0.05) and also in rats ventilated with HTV. EGCG could significantly inhibit HTV-induced local mtDNA release and attenuate the level of inflammatory lung injuries (reduced infiltration of local inflammatory cells, lower lung wet/dry ratio and expression levels of inflammatory cytokines). The beneficial effects of EGCG on preventing inflammatory lung injuries were in a concentration-dependent manner. Meanwhile, higher expression levels of mtDNA and inflammatory cytokines were observed in the media of cyclic stretched cell culture compared to those in the control group (p < 0.05). Furthermore, intra-tracheal administration of mtDNA in rats could lead to a marked increase of local inflammatory cytokines and subsequent inflammatory lung injuries (p < 0.05). And by adding mtDNA into the cell culture, higher level of inflammatory cytokines in the media was detected (p < 0.05). EGCG also showed preventive effects on inflammatory responses on a concentration-dependent manner (p < 0.05).

CONCLUSION

The increased expression level of mtDNA and subsequent inflammatory cytokines overproduction may play an important role in the development of VILI. EGCG may be a potential novel therapeutic candidate for protection against VILI by inhibiting the local release of mtDNA.

Inhibition of Methylglyoxal-Induced Histone H1 Nε-Carboxymethyllysine Formation by (+)-Catechin

Reactive dicarbonyl species (RCS) such as methylglyoxal (MGO) and glyoxal (GO) are common intermediates in protein damage, leading to the formation of advanced glycation end products (AGEs) through nonenzymatic glycation. (+)-Catechin, a natural plant extract from tea, has been evaluated for its ability in trapping GO and MGO. However, (+)-catechin is also reported to have both antioxidant ability and pro-oxidant properties. Until now, whether (+)-catechin can inhibit the formation of nonenzymatic glycation and the mechanism of the inhibition in nucleoprotein nonenzymatic glycation is still unclear. In the present study, histone H1 and MGO were used to establish an in vitro (100 mM phosphate buffer solution (PBS), pH 7.4, 37 °C) protein glycation model to study the trapping ability of (+)-catechin. Our data show that MGO caused dose-dependent protein damage, and the content of MGO-induced Schiff base formation was inhibited by (+)-catechin when the molecular ratio of catechin:MGO was 1:6. The formation of N^ε-carboxymethyllysine (CML) was reduced significantly when the ratio of (+)-catechin and MGO was 1:1, which was similar to the inhibition effect of aminoguanidine (AG). The formation of CML under in vitro conditions can be inhibited by low concentration (12.5-100 μM) of (+)-catechin but not with high concentration (200-800 μM) of (+)-catechin. The reason is that the high concentration of (+)-catechin did not inhibit CML formations due to H₂O₂ produced by (+)-catechin. In the presence of catalase, catechin can inhibit MGO-induced CML formation. In conclusion, the trapping ability of (+)-catechin may be more effective at the early stage of nonenzymatic glycation. However, a high concentration (200-800 μM) of (+)-catechin may not inhibit the formation of CML because it induced the increase of H₂O₂ formation.

Paradoxical cardiotoxicity of intraperitoneally-injected epigallocatechin gallate preparation in diabetic mice

Numerous clinical and bioavailability studies addressed epigallocatechin gallate (EGCG) beneficial effects; however, our previous work revealed EGCG-induced nephrotoxicity in the presence of diabetes. In this study, the potential myocardial toxicity of EGCG preparation (100 mg/kg/day, IP; 4 days) in diabetic mice injected with streptozotocin (STZ; 150 mg/kg, IP) was investigated. Diabetic mice receiving EGCG preparation showed electrocardiographic changes in addition to elevation of both serum creatine kinase-MB and troponin-I levels accompanied by microscopic myocardial damage. Additionally, myocardial NADPH oxidase, lipid peroxides and nitrotyrosine were increased in the vicinity of decreases of nuclear factor erythroid 2-related factor 2, hemeoxygenase-1, reduced glutathione, total antioxidant capacity, glutathione peroxidase and reductase and heat shock protein 90. Moreover, in diabetic mice, EGCG preparation increased myocardial nuclear factor-kappa B and tumor necrosis factor-alpha in addition to pronounced overexpression of inducible nitric oxide synthase and active caspase-3. Therefore, this study substantiates that EGCG-mediated deterioration compromises diabetes-induced cardiotoxicity to solidify our previous report for its potential nephrotoxicity in the same experimental setting.

High-Polyphenol Sorghum Bran Extract Inhibits Cancer Cell Growth Through ROS Induction, Cell Cycle Arrest, and Apoptosis

As diet is one of the major controllable factors in cancer development, potentially chemopreventive foods are of significant interest to public health. One such food is sorghum (Sorghum bicolor), a cereal grain that contains varying concentrations of polyphenols. In a panel of 15 sorghum germplasm, we identified strains with higher polyphenol content than previously reported for this grain. Bran extracts from the germplasm with the highest and lowest polyphenol content were then tested against HepG2 and Caco2 cancer cells to assess effects on cancer cell viability, reactive oxygen species, apoptosis, DNA damage, cell cycle arrest, and protein expression patterns. High-polyphenol extracts, but not low-polyphenol extracts, reduced cell viability by inducing apoptosis and cell cycle arrest following production of reactive oxygen species and oxidative DNA damage. The results indicate that high-polyphenol sorghum bran extracts have potential anticancer properties and warrant further research, not only to test against specific cancers but also to elucidate underlying mechanisms of action.