Epigallocatechin gallate protects against nitric oxide-induced apoptosis via scavenging ROS and modulating the Bcl-2 family in human dental pulp cells

Effects of hydroxyapatite nanorods prepared through Elaeagnus Angustifolia extract on modulating immunomodulatory/dentin-pulp regeneration genes in DPSCs

Dental pulp stem cells (DPSCs) are a new type of mesenchymal stem cells (MSCs) found in the oral cavity with immunomodulation and tissue regeneration capacities. This study determined the impacts of nano-hydroxyapatite (nHA) prepared through Elaeagnus Angustifolia extract (EAE) to enhance the relative expression of immunomodulatory/dentin-pulp regeneration genes in DPSCs. To produce nHA and modified nHA via EAE (nHAEA), the sol-gel technique was used. The functional groups of nanoparticles (NPs), morphological, and optical features were determined using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) together with energy-dispersive X-ray analysis (EDAX), and Transmission electron microscopy (TEM). The cell viability was then determined using the MTT method in the presence of various EAE, nHA, and nHAEA concentrations. Target gene expression was quantified using a real-time PCR procedure after treating DPSCs with an optimally non-toxic dose of EAE and NPs. The presence of the HA phase was reported with the XRD and FTIR results. According to the results of SEM and TEM, the rod-like NPs could be fabricated. nHAEAs were found to be characterized with low crystallite size, reduced diameter, lengthier, needle-like, and less agglomerated particles compared with nHA. The real-time PCR results demonstrated that nHAEA remarkably increased the expression of human leukocyte antigen-G5 (HLA-G5), vascular endothelial growth factor (VEGF), dentin sialophosphoprotein (DSPP), and interleukin6 (IL6) genes compared to the nHA group. These findings suggest that nHAEAs might have the potential application in the stemness capability of DPSCs for the treatment of inflamed/damaged pulp.

The Role and Mechanisms of Action of Catechins in Neurodegenerative Diseases

The prevalence, incidence and mortality rates of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease are gradually increasing. New approaches are being developed to manage the progression and treatment of neurodegenerative diseases. Catechins, polyphenolic compounds, are key compounds that demonstrate therapeutic effects with their properties such as antioxidant, anti-inflammatory, anti-apoptotic properties in the prevention and treatment of neurodegenerative diseases. The therapeutic effects of catechins have been exhaustively studied in human and animal models. Catechins can have anti-inflammatory effects by suppressing inflammatory pathways and cytokines, as well as antioxidant effects such as chelating metal ions and scavenging radicals. They might reduce phosphorylation of tau proteins, aggregation of amyloid-beta and apoptotic proteins release. They can also decrease alpha-synuclein accumulation and increase dopamine levels. With all these effects, they can have an effect on neurodegenerative diseases. This review points to the potential mechanisms of catechins in neurodegenerative diseases, based on their findings in the literature review.Key teaching pointsCatechins can reduce amyloid-β plaque aggregation and tau phosphorylation.Catechins can decrease alfa-synuclein levels.Catechins can protect neuronal cells with their anti-apoptotic effect.More comprehensive studies are needed to clarify this issue.

Physiological Dose of EGCG Attenuates the Health Defects of High Dose by Regulating MEMO-1 in Caenorhabditis elegans

EGCG, as a dietary-derived antioxidant, has been extensively studied for its beneficial health effects. Nevertheless, it induces the transient increase in ROS and leads to the hormetic extension of lifespan. How exactly biology-benefiting effects with the minimum severe adverse are realized remains unclear. Here, we showed that physiological dose of EGCG could help moderate remission in health side effects exposed to high doses, including shortened lifespan, reduced body size, decreased pharyngeal pumping rate, and dysfunctional body movement in C. elegans. Furthermore, we found this result was caused by the physiological dose of EGCG to block the continued ROS accumulation and triggered acclimation responses after stressor removal. Also, in this process, we observed that EGCG downregulated the key redox protein MEMO-1 to activate the feedback loop of NADPH oxidase-mediated redox signaling. Our data indicates that the feedback signal induced by NADPH oxidase may contribute to the health-protective mechanism of dietary polyphenols in vivo.

Effects of epigallocatechin gallate (EGCG) on the biological properties of human dental pulp stem cells and inflammatory pulp tissue

OBJECTIVE

This study aimed to investigate the effect of epigallocatechin gallate (EGCG) on the proliferation, mineralization, inflammation and hypoxia responses of human dental pulp stem cells (hDPSCs) in vitro and its effect on inflammatory pulp tissue in rats in vivo.

DESIGN

The optimum concentration of EGCG was selected by creating a dose response curve. Expression of odontogenic/osteogenic-related genes and inflammatory cytokines after stimulation with Lipopolysaccharide (LPS) was detected by real-time PCR. Under hypoxic conditions, cell proliferation and expression of reactive oxygen species (ROS) and superoxide dismutase (SOD) were detected.In vivo, the maxillary first molars of SD rats were pulpotomized and stimulated with 5 mg/mL LPS for 30 min. Normal saline and EGCG were used to flush the pulp chamber. After 2 months, samples were removed for micro-CT scanning and HE staining.

RESULTS

CCK-8 assay revealed that 10 μg/mL EGCG had no significant effect on the proliferation of hDPSCs. EGCG inhibited expression of IL-1β, IL-6, and TNF-α. Furthermore, EGCG rescued cell proliferation ability, increased SOD activity and reduced ROS expression under hypoxia.In vivo, reduced inflammatory cell accumulation was observed in the coronal pulp in the EGCG group, while in the control group, diffuse inflammatory cells were observed in the radicular pulp.

CONCLUSION

EGCG had no obvious effects on calcified nodule formation but significantly inhibited the inflammatory response of hDPSCs and inhibited apoptosis of hDPSCs caused by hypoxia injury. In vivo, EGCG exerts inhibitory effects on pulp tissue inflammation.

Use of leptin-conjugated phosphatidic acid liposomes with resveratrol and epigallocatechin gallate to protect dopaminergic neurons against apoptosis for Parkinson's disease therapy

Complex liposomes were assembled with 1,2-distearoyl-sn-glycero-3-phosphocholine, dihexadecyl phosphate (DHDP), cholesterol and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate (PA) to act as drug carriers for resveratrol (RES) and epigallocatechin gallate (EGCG). The liposomes were modified with leptin (Lep) on the surface to cross the blood-brain barrier (BBB) and to rescue degenerated dopaminergic neurons. The activity of RES and EGCG against neurotoxicity was investigated using an in vitro neurodegenerative model established by SH-SY5Y cells with an insult of 1-methyl-4-phenylpyridinium (MPP⁺). The results indicated that increasing the mole percentage of DHDP and PA increased the particle size and absolute zeta potential value, and improved the entrapment efficiency of RES and EGCG; however, this increase reduced the release rate of RES and EGCG and the grafting efficiency of Lep. The ability of Lep/RES-EGCG-PA-liposomes to cross the BBB was found to be higher than that of non-modified liposomes. Further, the addition of PA and Lep into liposomes enhanced cell viability and target efficiency. The immunofluorescence results demonstrated that the conjugation of Lep with liposomes enabled the docking of HBMECs and SH-SY5Y cells via Lep receptor, and enhanced their ability to permeate the BBB and cellular uptake. Immunofluorescence and western blot analysis also revealed that RES and EGCG encapsulated into liposomes could be a neural defensive strategy by reducing the apoptosis promotor protein Bcl-2 associated X protein and α-synuclein, and enhancement in the apoptosis inhibitor protein B cell lymphoma 2, tyrosine hydroxylase, and the dopamine transporter. Hence, Lep-PA-liposomes can be an excellent choice of potential delivery system for PD treatment.

A novel quinolinylmethyl substituted ethylenediamine compound exerts anti-cancer effects via stimulating the accumulation of reactive oxygen species and NO in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. Owing to the limitations in the current therapeutic strategies for treating HCC, development of novel chemotherapeutic drugs is urgently needed. In the present study, we found that QQM, a newly-synthesized quinolinylmethyl substituted ethylenediamine compound, exhibited anti-HCC effects both in vitro and in vivo. QQM inhibited HCC cell growth and induced G0/G1-phase cell cycle arrest and apoptosis in a dose-dependent manner. Our results showed that QQM acted by significantly increasing intracellular reactive oxygen species in HCC cells, which led to cell apoptosis and growth inhibition. Furthermore, QQM treatment resulted in an accumulation of reactive nitric oxide (NO) in HCC cells, and introduction of a NO scavenger, carboxy-PTIO, largely attenuated QQM-induced cytotoxicity. Finally, we found that QQM inhibited growth and induced apoptosis of HCC xenograft tumors in vivo. Taken together, our results indicated that QQM exerted anti-HCC effects by inducing reactive oxygen species and NO accumulation in HCC cells. Thus, QQM exhibits the qualities of a novel, promising anti-tumor candidate for the treatment of HCC.

Physiopathology of nitric oxide in the oral environment and its biotechnological potential for new oral treatments: a literature review

OBJECTIVES

A narrative review on the NO properties and their relationship with the oral environment describing NO's molecular origin, role, and perspectives regarding oral pathological, physiological, and regenerative processes for future applications and possible use as prevention or treatment in dentistry.

MATERIALS AND METHODS

Pubmed was searched using the word "nitric oxide." Reviews, clinical studies, and experimental studies were eligible for the screening process. Similar search procedures were then performed with the additional search words "conservative dentistry," "orthodontics," "endodontics," "implants," "periodontics," "oral cancer," "pulp revascularization," and "oral surgery." Furthermore, references of included articles were examined to identify further relevant articles.

RESULTS

There is a relationship between NO production and oral diseases such as caries, periodontal diseases, pulp inflammation, apical periodontitis, oral cancer, with implants, and orthodontics. Studies on this relationship and uses of NO, in diagnosis, prevention, and treatment, are being developed. Also, some NO and oral cavity patents have already registered.

CONCLUSIONS

The understanding of how NO can interfere in oral health maintenance or disease processes can contribute to elucidate the disease development and optimize treatment approaches.

CLINICAL RELEVANCE

NO has considerable biotechnological potential and can contribute to improving diagnostics and treating the oral environment. As a biomarker, NO has an important role in the early diagnosis of diseases. Regarding treatments, NO can possibly be used as a regulator of inflammation, anti-biofilm action, replacing antibiotics, inducing apoptosis of cancerous cells, and contributing to the angiogenesis. All these studies are initial considerations regarding the relationship between NO and dentistry.

Polyphenols in Dental Applications

(1) Background: polyphenols are a broad class of molecules extracted from plants and have a large repertoire of biological activities. Biomimetic inspiration from the effects of tea or red wine on the surface of cups or glass lead to the emergence of versatile surface chemistry with polyphenols. Owing to their hydrogen bonding abilities, coordination chemistry with metallic cations and redox properties, polyphenols are able to interact, covalently or not, with a large repertoire of chemical moieties, and can hence be used to modify the surface chemistry of almost all classes of materials. (2) Methods: the use of polyphenols to modify the surface properties of dental materials, mostly enamel and dentin, to afford them with better adhesion to resins and improved biological properties, such as antimicrobial activity, started more than 20 years ago, but no general overview has been written to our knowledge. (3) Results: the present review is aimed to show that molecules from all the major classes of polyphenolics allow for low coast improvements of dental materials and engineering of dental tissues.

Nitric Oxide in Dental Pulp Tissue: From Molecular Understanding to Clinical Application in Regenerative Endodontic Procedures

Nitric oxide (NO), which is synthesized by the enzyme NO synthase (NOS), is a versatile endogenous molecule with multiple biological effects on many tissues and organs. In dental pulp tissue, NO has been found to play multifaceted roles in regulating physiological activities, inflammation processes, and tissue repair events, such as cell proliferation, neuronal degeneration, angiogenesis, and odontoblastic differentiation. However, there is a deficiency of detailed discussion on the NO-mediated interactions between inflammation and reparative/regenerative responses in wounded dental pulp tissue, which is a central determinant of ultimate clinical outcomes. Thus, the purpose of this review is to outline the current molecular understanding on the roles of Janus-faced molecule NO in dental pulp physiology, inflammation, and reparative activities. Based on this knowledge, advanced physicochemical techniques designed to manipulate the therapeutic potential of NOS and NO production in endodontic regeneration procedures are further discussed. Impact statement The interaction between inflammation and reparative/regenerative responses is very important for regenerative endodontic procedures, which are biologically based approaches intended to replace damaged tissues. Inside dental pulp tissue, endogenous nitric oxide (NO) is generated mainly by immunocompetent cells and dental pulp cells and mediates not only inflammatory/immune activities but also signaling cascades that regulate tissue repair and reconstruction, indicating its involvement in both tissue destruction and regeneration. Thus, it is feasible that NO acts as one of the indicators and modulators in dental pulp repair or regeneration under physiological and pathological conditions.

Cerebral protection of epigallocatechin gallate (EGCG) via preservation of mitochondrial function and ERK inhibition in a rat resuscitation model

Background

Various and opposite roles of epigallocatechin gallate (EGCG) have been reported in different studies. We aimed to investigate how EGCG affects the cerebral injury in a cardiac arrest/cardiopulmonary resuscitation (CA/CPR) model of rat.

Methods

The rats which were subjected to CA/CPR randomly received low dose of EGCG (3 mg/kg, Low-EGCG group, n=16), high dose of EGCG (9 mg/kg, High-EGCG group, n=16) and equal volume of 0.9% saline solution (NS group, n=16) at the first minute after return of spontaneous circulation (ROSC). The rats underwent anesthesia and intubation were defined as Sham group (n=16). Twenty-four hours after ROSC, neural defect score (NDS), ROS fluorescence intensity, degree of mitochondrial permeability transition pore (mPTP) opening, ATP contents and mitochondrial ATP synthase expression were evaluated in the four groups. The expression of extracellular signal-regulated kinase (ERK) activity and cleaved-caspase 3 were also detected by Western blot.

Results

CA/CPR induced severe ischemia-reperfusion injury (IRI), resulted in mitochondrial dysfunction and upregulated phosphorylation of ERK. EGCG dose-dependently alleviated the IRI after CA/CPR, inhibited ERK activity and restored mitochondrial function and, as indicated by improved NDS, reduced ROS level, decreased mPTP opening, elevated ATP content, increased ATPase expression and downregulated cleaved-caspase 3 level.

Conclusion

EGCG alleviated global cerebral IRI by restoring mitochondrial dysfunction and ERK modulation in a rat CA/CPR model, which might make it a potential candidate agent against IRI after CA/CPR in the future. Further study is needed to determine whether higher dosage of EGCG might aggravate cerebral IRI post-CA/CPR.

Epigallocatechin gallate attenuates arsenic induced genotoxicity via regulation of oxidative stress in balb/C mice

Arsenic is well known genotoxicant which causes the excessive generation of reactive oxygen species (ROS) and inhibition of antioxidant enzyme systems leading to cell damage through the activation of oxidative sensitive signaling pathways. Epigallocatechin gallate (EGCG), the main and active polyphenolic catechin present in green tea, has shown potent antioxidant, free radical scavenging and genoprotective activity in vivo. The present study attempted to investigate antioxidant and geno-protective efficacy of EGCG by regulating arsenic induced oxidative stress in mice. Animals received prophylactic and therapeutic treatments at two different doses (25 and 50 mg/kg b.wt.) of EGCG orally for 15 days and administered arsenic intraperitoneally at dose of 1.5 mg/kg b.wt (1/10th of LD₅₀) for 10 days. Arsenic intoxication revealed enhanced ROS production (114%) in lymphocytes; elevated levels of LPO (2-4 fold); reduced levels of hepato-renal antioxidants (approx. 45%) and augmented genomic fragmentation in hepato-renal tissues; increased chromosomal anomalies (78%) and micronucleation (21.93%) in bone marrow cells and comet tailing (25%) in lymphocytes of mice. Both pre and post treatments of EGCG decreased ROS production, restored lipid peroxidation (LPO) and reduced hepato-renal antioxidants levels, reduced the DNA fragmentation, number of chromosomal aberrations (CA), micronucleation (MN), and comet tailing but prophylactic treatment of 50 mg/kg b.wt was the most effective treatment in regulating arsenic induced oxidative stress. The effectiveness of this dose was furthermore validated by calculating the inhibitory index. Thus, results of present work empirically demonstrate free radical scavenging, anti-oxidative and genoprotective efficacy of EGCG against arsenic toxicity.

The critical role of epigallocatechin gallate in regulating mitochondrial metabolism

Epigallocatechin gallate (EGCG), one of polyphenols isolated from green tea, exhibits biology-benefiting effects with minimum severe adverse. EGCG is known to be a mitochondrion-targeting medicinal agent, regulating mitochondrial metabolism, including mitochondrial biogenesis, mitochondrial bioenergetics, and mitochondria-mediated cell cycle and apoptosis. EGCG might exhibit either antioxidative activity to prevent against oxidative stress or pro-oxidative activity to counteract cancer cells, which depends on the cellular stress situations, cell types and the concentration of EGCG. Recent research has gained positive and promising data. This review will discuss the interaction between EGCG and mitochondrion.

The critical role of epigallocatechin gallate in regulating mitochondrial metabolism

Epigallocatechin gallate (EGCG), one of polyphenols isolated from green tea, exhibits biology-benefiting effects with minimum severe adverse. EGCG is known to be a mitochondrion-targeting medicinal agent, regulating mitochondrial metabolism, including mitochondrial biogenesis, mitochondrial bioenergetics, and mitochondria-mediated cell cycle and apoptosis. EGCG might exhibit either antioxidative activity to prevent against oxidative stress or pro-oxidative activity to counteract cancer cells, which depends on the cellular stress situations, cell types and the concentration of EGCG. Recent research has gained positive and promising data. This review will discuss the interaction between EGCG and mitochondrion.

Impact of epigallocatechin‑3‑gallate on expression of nuclear factor erythroid 2‑related factor 2 and γ‑glutamyl cysteine synthetase genes in oxidative stress‑induced mouse renal tubular epithelial cells

The aim of the present study was to investigate the antioxidant response mechanism of epigallocatechin‑3‑gallate (EGCG) in H2O2‑induced mouse renal tubular epithelial cells (MRTECs). The cultured MRTECs were divided into normal, H2O2 (control) and EGCG treatment groups. The MTT assay was used to assess cell viability, and reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR), immunocytochemical and western blot analyses were performed to detect the expression of nuclear factor erythroid 2‑related factor 2 (Nrf2) and γ‑glutamyl cysteine synthetase (γ‑GCS). EGCG was able to mitigate H2O2‑mediated cell damage. The RT‑qPCR results demonstrated that EGCG was able to upregulate the gene expression of Nrf2 and γ‑GCS in MRTECs in a dose‑dependent manner. The immunocytochemistry and western blot analyses demonstrated that EGCG was able to increase the protein expression of Nrf2 and γ‑GCS in MRTECs in a dose‑dependent manner. Oxidative stress may lead to a decrease in the viability of MRTECs, while EGCG was able to promote the expression of Nrf2 and γ‑GCS in MRTECs, thereby improving the antioxidant capacity of the cells and promoting the repair of oxidative stress injury.

Epigallocatechin-3-gallate inhibits adipogenesis through down-regulation of PPARγ and FAS expression mediated by PI3K-AKT signaling in 3T3-L1 cells

Epigallocatechin-3-gallate (EGCG), a major component in green tea, functions as extensive bioactivities including anti-inflammation, anti-oxidation, and anti-cancer. However, little is known about its anti-adipogenesis and underlying mechanisms. The purport of this study sought to investigate effects of EGCG on 3T3-L1 preadipocyte differentiation and to explore its possible mechanisms. The 3T3-L1 cells were induced to differentiate under the condition of pro-adipogenic cocktail with or without indicated EGCG concentrations (10, 50, 100, 200µM) for 2, 4, 6 and 8 days, respectively. Also, another batch of 3T3-L1 cells was induced under the optimal EGCG concentration (100µM) with or without SC3036 (PI3K activator, 10µM) or SC79 (AKT activator, 0.5µM) for 8 days. Subsequently, the cell viability was examined by MTT assay and the cell morphology was visualized by Oil red O staining. Finally, the mRNA levels including peroxisome proliferator activated receptor γ (PPARγ) and fatty acid synthase (FAS) were detected by quantitative real time PCR, while the protein levels of PPARγ, FAS, phosphatidylinositol 3 kinase (PI3K), insulin receptor substrate1(IRS1), AKT, and p-AKT were measured by immunoblotting analysis. Our results showed that EGCG inhibited adipogenesis of 3T3-L1 preadipocyte in a concentration-dependent manner. Moreover, the inhibitory effects were reversed by SC3036 or SC79, suggesting that the inhibitory effects of EGCG are mediated by PI3K-AKT signaling to down-regulate PPARγ and FAS expression levels. The findings shed light on EGCG anti-adipogenic effects and its underlying mechanism and provide a novel preventive-therapeutic potential for obesity subjects as a compound from Chinese green tea.

Potential neuroprotective properties of epigallocatechin-3-gallate (EGCG)

Neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) enforce an overwhelming social and economic burden on society. They are primarily characterized through the accumulation of modified proteins, which further trigger biological responses such as inflammation, oxidative stress, excitotoxicity and modulation of signalling pathways. In a hope for cure, these diseases have been studied extensively over the last decade to successfully develop symptom-oriented therapies. However, so far no definite cure has been found. Therefore, there is a need to identify a class of drug capable of reversing neural damage and preventing further neural death. This review therefore assesses the reliability of the neuroprotective benefits of epigallocatechin-gallate (EGCG) by shedding light on their biological, pharmacological, antioxidant and metal chelation properties, with emphasis on their ability to invoke a range of cellular mechanisms in the brain. It also discusses the possible use of nanotechnology to enhance the neuroprotective benefits of EGCG.

Epigallocatechin-3-gallate suppresses the lipid deposition through the apoptosis during differentiation in bovine bone marrow mesenchymal stem cells

Epigallocatechin gallate (EGCG), a major component of tea, has known effects on obesity, fatty liver, and obesity-related cancer. We explored the effects of EGCG on the differentiation of bovine mesenchymal stem cells (BMSCs, which are multipotent) in a dose- and time-dependent manner. Differentiating BMSCs were exposed to various concentrations of EGCG (0, 10, 50, 100, and 200 µM) for 2, 4, and 6 days. BMSCs were cultured in Dulbecco's modified Eagle's medium (DMEM)/high-glucose medium with adipogenic inducers for 6 days, and the expression levels of various genes involved in adipogenesis were measured using real-time polymerase chain reaction (PCR) and Western blotting. We assessed apoptosis by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining of control and EGCG-exposed cells. We found that EGCG significantly suppressed fat deposition and cell viability (P < 0.05). The mRNA and protein levels of various adipogenic factors were measured. Expression of the genes encoding peroxisome proliferator-activated receptor gamma (PPARG), CCAAT/enhancer-binding protein alpha (CEBPA), fatty acid-binding protein 4 (FABP4), and stearoyl-CoA desaturase (SCD) were diminished by EGCG during adipogenic differentiation (P < 0.05). We also found that EGCG lowered the expression levels of the adipogenic proteins encoded by these genes (P < 0.05). EGCG induced apoptosis during adipogenic differentiation (P < 0.05). Thus, exposure to EGCG potentially inhibits adipogenesis by triggering apoptosis; the data suggest that EGCG inhibits adipogenic differentiation in BMSCs.

Polyphenols and mitochondria: an update on their increasingly emerging ROS-scavenging independent actions

Polyphenols, ubiquitously present in fruits and vegetables, have been traditionally viewed as antioxidant molecules. Such contention emerged, mainly from their well established in vitro ability to scavenge free radicals and other reactive oxygen species (ROS). During the last decade, however, increasing evidence has emerged supporting the ability of certain polyphenols to also exert numerous ROS-scavenging independent actions. Although the latter can comprise the whole cell, particular attention has been placed on the ability of polyphenols to act, whether favorably or not, on a myriad of mitochondrial processes. Thus, some particular polyphenols are now recognized as molecules capable of modulating pathways that define mitochondrial biogenesis (i.e., inducing sirtuins), mitochondrial membrane potential (i.e., mitochondrial permeability transition pore opening and uncoupling effects), mitochondrial electron transport chain and ATP synthesis (i.e., modulating complexes I to V activity), intra-mitochondrial oxidative status (i.e., inhibiting/inducing ROS formation/removal enzymes), and ultimately mitochondrially-triggered cell death (i.e., modulating intrinsic-apoptosis). The present review describes recent evidence on the ability of some polyphenols to modulate each of the formerly mentioned pathways, and discusses on how, by acting on such mitochondrial processes, polyphenols may afford protection against those mitochondrial damaging events that appear to be key in the cellular toxicity induced by various xenobiotics as well as that seen during the development of several ROS-related diseases.