The main catechin of green tea, (-)-epigallocatechin-3-gallate (EGCG), reduces bleomycin-induced DNA damage in human leucocytes

Targeting the DNA damage response (DDR) of cancer cells with natural compounds derived from Panax ginseng and other plants

DNA damage is a driver of cancer formation, leading to the impairment of repair mechanisms in cancer cells and rendering them susceptible to DNA-damaging therapeutic approaches. The concept of "synthetic lethality" in cancer clinics has emerged, particularly with the use of PARP inhibitors and the identification of DNA damage response (DDR) mutation biomarkers, emphasizing the significance of targeting DDR in cancer therapy. Novel approaches aimed at genome maintenance machinery are under development to further enhance the efficacy of cancer treatments. Natural compounds from traditional medicine, renowned for their anti-aging and anticarcinogenic properties, have garnered attention. Ginseng-derived compounds, in particular, exhibit anti-carcinogenic effects by suppressing reactive oxygen species (ROS) and protecting cells from DNA damage-induced carcinogenesis. However, the anticancer therapeutic effect of ginseng compounds has also been demonstrated by inducing DNA damage and blocking DDR. This review concentrates on the biphasic effects of ginseng compounds on DNA mutations-both inhibiting mutation accumulation and impairing DNA repair. Additionally, it explores other natural compounds targeting DDR directly, providing potential insights into enhancing cancer therapy efficacy.

The ameliorative effect of rosmarinic acid and epigallocatechin gallate against doxorubicin-induced genotoxicity

Doxorubicin (Dox), an effective anticancer agent, is known for its genotoxic effects on normal cells. Phenolic compounds, renowned for their antitumor, antioxidant, and antigenotoxic properties, have gained prominence in recent years. This study investigates the individual and combined protective effects of rosmarinic acid (RA) and epigallocatechin gallate (EGCG) against Dox-induced genotoxicity using various in vitro test systems. The synergistic/antagonistic interaction of these combinations on Dox's chemotherapeutic effect is explored in breast cancer cell lines. Both RA and EGCG significantly mitigate Dox-induced genotoxicity in comet, micronucleus, and Ames assays. While Dox exhibits higher selectivity against MCF-7 cells, EGCG and RA show greater selectivity against MDA-MB-231 cells. The coefficient of drug interaction reveals a synergistic effect when RA or EGCG is combined with Dox in breast cancer cells. In conclusion, both EGCG and RA effectively reduce Dox-induced genetic damage and enhance Dox's cell viability-reducing effect in breast cancer cells.

Investigation of the protective role of Ginkgo biloba L. against phytotoxicity, genotoxicity and oxidative damage induced by Trifloxystrobin

Trifloxystrobin (TFS) is a widely used strobilurin class fungicide. Ginkgo biloba L. has gained popularity due to its recognized medicinal and antioxidant properties. The aim of this study was to determine whether Ginkgo biloba L. extract (Gbex) has a protective role against TFS-induced phytotoxicity, genotoxicity and oxidative damage in A. cepa. Different groups were formed from Allium cepa L. bulbs subjected to tap water (control), 200 mg/L Gbex (Gbex1), 400 mg/L Gbex (Gbex2), 0.8 g/L TFS solution (TFS), 200 mg/L Gbex + 0.8 g/L TFS (TFS + Gbex1) and 400 mg/L Gbex + 0.8 g/L TFS (TFS + Gbex2), respectively. The phenolic composition of Gbex and alterations in the morphological, physiological, biochemical, genotoxicity and anatomical parameters were evaluated. Rutin, protocatechuic acid, catechin, gallic acid, taxifolin, p-coumaric acid, caffeic acid, epicatechin, syringic acid and quercetin were the most prevalent phenolic substances in Gbex. Rooting percentage, root elongation, weight gain, chlorophyll a and chlorophyll b decreased by approximately 50%, 85%, 77%, 55% and 70%, respectively, as a result of TFS treatment compared to the control. In the TFS group, the mitotic index fell by 28% compared to the control group, but chromosomal abnormalities, micronuclei frequency and tail DNA percentage increased. Fragment, vagrant chromosome, sticky chromosome, uneven chromatin distribution, bridge, vacuole-containing nucleus, reverse polarization and irregular mitosis were the chromosomal abnormalities observed in the TFS group. The levels of proline (2.17-fold) and malondialdehyde (2.71-fold), as well as the activities of catalase (2.75-fold) and superoxide dismutase (2.03-fold) were increased by TFS in comparison to the control. TFS-provoked meristematic disorders were damaged epidermis and cortex cells, flattened cell nucleus and thickened cortex cell wall. Gbex combined with TFS relieved all these TFS-induced stress signs in a dose-dependent manner. This investigation showed that Gbex can play protective role in A. cepa against the phytotoxicity, genotoxicity and oxidative damage caused by TFS. The results demonstrated that Gbex had this antioxidant and antigenotoxic potential owing to its high phenolic content.

Genotoxic and genoprotective effects of phytoestrogens: a systematic review

Phytoestrogens are xenoestrogens found in plants with a myriad of health benefits. However, various studies reported the genotoxic effects of these substances. Thus, we reviewed in vitro and in vivo studies published in PubMed, Scopus, and Web of Science to evaluate the genotoxic and the genoprotective potential of phytoestrogens. Only studies written in English and intended to study commercially available phytoestrogens were included. The screening was performed manually. Moreover, the underlying mechanism of action of phytoestrogens was described. Around half of those studies (43%) reported genoprotective results. However, several studies revealed positive results for genotoxicity with specific model organisms and with dose/concentration dependence. The assessment of the selected articles showed substantial differences in the used concentrations and a biphasic response was recorded in some phytoestrogens. As far as we know, this is the first study to assess the genotoxic and genoprotective effects of phytoestrogens systematically.

Chemico-biological aspects of (-)-epigallocatechin-3-gallate (EGCG) to improve its stability, bioavailability and membrane permeability: Current status and future prospects

Natural products have been a bedrock for drug discovery for decades. (-)-Epigallocatechin-3-gallate (EGCG) is one of the widely studied natural polyphenolic compounds derived from green tea. It is the key component believed to be responsible for the medicinal value of green tea. Significant studies implemented in in vitro, in cellulo, and in vivo models have suggested its anti-oxidant, anti-cancer, anti-diabetic, anti-inflammatory, anti-microbial, neuroprotective activities etc. Despite having such a wide array of therapeutic potential and promising results in preclinical studies, its applicability to humans has encountered with rather limited success largely due to the poor bioavailability, poor membrane permeability, rapid metabolic clearance and lack of stability of EGCG. Therefore, novel techniques are warranted to address those limitations so that EGCG or its modified analogs can be used in the clinical setup. This review comprehensively covers different strategies such as structural modifications, nano-carriers as efficient drug delivery systems, synergistic studies with other bioactivities to improve the chemico-biological aspects (e.g., stability, bioavailability, permeability, etc.) of EGCG for its enhanced pharmacokinetics and pharmacological properties, eventually enhancing its therapeutic potentials. We think this review article will serve as a strong platform with comprehensive literature on the development of novel techniques to improve the bioavailability of EGCG so that it can be translated to the clinical applications.

Mitigative effect of green tea extract against mercury(II) chloride toxicity in Allium cepa L. model

Mercury (Hg) is a highly toxic heavy metal for all organisms. In the present study, the mitigative role of 190 mg/L and 380 mg/L doses of green tea extract (GTex) against mercury(II) chloride (HgCI₂)-induced toxicity was evaluated in Allium cepa L. For this aim, selected physiological, genotoxicity, and biochemical parameters as well as meristematic cell injuries in the roots were investigated. Ratios of catechin and caffeine in GTex were determined by HPLC analysis. Also, free radical scavenging activity of GTex was tested against superoxide and hydrogen peroxide radicals. As a result of HgCI₂ application, germination percentage, root elongation, weight gain, and mitotic index (MI) declined, while the frequency of micronucleus (MN), chromosomal abnormalities (CAs), and meristematic cell damages increased. HgCI₂ administration also led to a significant increase in malondialdehyde content, superoxide dismutase, and catalase activities which are signs of oxidative stress. On contrary, applications of GTex together with HgCI₂ reduced HgCI₂-induced adverse effects in all parameters in a dose-dependent manner. Antioxidant components in GTex were listed as caffeine, epigallocatechin gallate, epigallocatechin, epicatechin gallate, and catechin according to their abundance. GTex exhibited a strong scavenging ability in the presence of superoxide and hydrogen peroxide radicals. The present study revealed the strong protective capacity of GTex against HgCI₂-induced toxicity in A. cepa owing to its high antioxidant content with a multifaceted perspective. With this study, a reliable starting point was established for future studies investigating the more common and diverse use of GTex against toxic substances.

Assessment of Antioxidant, Immunomodulatory Activity of Oxidised Epigallocatechin-3-Gallate (Green Tea Polyphenol) and Its Action on the Main Protease of SARS-CoV-2—An In Vitro and In Silico Approach

Owing to the instability of Epigallocatechin Gallate (EGCG), it may undergo auto-oxidation and form oxidised products or dimers. In the present study, we aimed to evaluate the therapeutic effects, including antioxidation and immunomodulatory action, of the Oxidised Epigallocatechin Gallate (O-EGCG) as compared to native EGCG and the action of these compounds on main protease (Mpro) docking against SARS-CoV-2. HCT-116 (Human Colon Cancer) cell lines were used to estimate the total antioxidant capacity and lipid peroxidation levels and pro-inflammatory markers (human IL-6, IL-1β, TNF-α). Further, molecular docking analysis was performed by AutoDock and visualised in Discovery studio. Improved antioxidant capacity of O-EGCG was observed, and there was a significant decrease in the inflammatory markers (IL-1β, IL-6, and TNF-α) when O-EGCG was applied as compared to EGCG. The O-EGCG was shown to be strongly associated with the highest docking score and active site residues of IL-1, IL-6, and TNF- α, as well as the Mpro of SARS-CoV-2, according to in silico approach. The in vitro and in silico analyses indicate an improved therapeutic action of the oxidised form of EGCG. The effective inhibitory action of O-EGCG against SARS-CoV-2 suggests further exploration of the compound against COVID-19 and its efficacy. However, in vivo studies and understanding of the mechanism of action of O-EGCG may yield a better opinion on the use of O-EGCG and future human clinical trials.

Natural Compounds That Target DNA Repair Pathways and Their Therapeutic Potential to Counteract Cancer Cells

Resistance to current cancer treatments is an important problem that arises through various mechanisms, but one that stands out involves an overexpression of several factors associated with DNA repair. To counteract this type of resistance, different drugs have been developed to affect one or more DNA repair pathways, therefore, to test different compounds of natural origin that have been shown to induce cell death in cancer cells is paramount. Since natural compounds target components of the DNA repair pathways, they have been shown to promote cancer cells to be resensitized to current treatments. For this and other reasons, natural compounds have aroused great curiosity and several research projects are being developed around the world to establish combined treatments between them and radio or chemotherapy. In this work, we summarize the effects of different natural compounds on the DNA repair mechanisms of cancer cells and emphasize their possible application to re-sensitize these cells.

Tea polyphenol protects against cisplatin-induced meiotic defects in porcine oocytes

DDP (cisplatin), a DNA cross-linking agent, is one of the most common chemotherapeutic drugs that have been widely used in the treatment of sarcomas and germ cell tumors. DDP treatment exhibits severe side effects including renal toxicity, ototoxicity and embryo-toxicity. Women of reproductive age treated with DDP may lead to loss of primordial follicles, resulting in the depletion of the ovarian reserve and consequent premature ovarian failure. However, the influence of DDP on the oocyte quality and the strategy to prevent it has not yet fully clarified. Here, we report that DDP exposure resulted in the oocyte meiotic failure via disrupting the meiotic organelle dynamics and arrangement, exhibiting a prominently impaired cytoskeleton assembly, including spindle formation and actin polymerization. In addition, exposure to DDP led to the abnormal distribution of mitochondrion and cortical granules, two indicators of cytoplasmic maturation of oocytes. Conversely, TP (tea polyphenols) supplementation partially restored all of the meiotic defects resulted from DDP exposure through suppressing the increase of ROS level and the occurrence of DNA damage as well as apoptosis.

DNA-BINDING and DNA-protecting activities of small natural organic molecules and food extracts

The review summarizes literature data on the DNA-binding, DNA-protecting and DNA-damaging activities of a range of natural human endogenous and exogenous compounds. Small natural organic molecules bind DNA in a site-specific mode, by arranging tight touch with the structure of the major and minor grooves, as well as individual bases in the local duplex DNA. Polyphenols are the best-studied exogenous compounds from this point of view. Many of them demonstrate hormetic effects, producing both beneficial and damaging effects. An attempt to establish the dependence of DNA damage or DNA protection on the concentration of the compound turned out to be successful for some polyphenols, daidzein, genistein and resveratrol, which were DNA protecting in low concentrations and DNA damaging in high concentrations. There was no evident dependence on concentration for quercetin and kaempferol. Probably, the DNA-protecting effect is associated with the affinity to DNA. Caffeine and theophylline are DNA binders; at the same time, they favor DNA repair. Although most alkaloids damage DNA, berberine can protect DNA against damage. Among the endogenous compounds, hormones belonging to the amine class, thyroid and steroid hormones appear to bind DNA and produce some DNA damage. Thus, natural compounds continue to reveal beneficial or adverse effects on genome integrity and provide a promising source of therapeutic activities.

Non-canonical (non-SMAD2/3) TGF-β signaling in fibrosis: Mechanisms and targets

Transforming growth factor (TGF)-β uses several intracellular signaling pathways besides canonical ALK5-Smad2/3 signaling to regulate a diverse array of cellular functions. Several of these so-called non-canonical (non-Smad2/3) pathways have been implicated in the pathogenesis of fibrosis and may therefore represent targets for therapeutic intervention. This review summarizes our current knowledge on the mechanisms of non-canonical TGF-β signaling in fibrosis, the potential molecular targets and the use of agonists/antagonists for therapeutic intervention.

The Mediterranean Diet and Breast Cancer: A Personalised Approach

There have been many original and review articles summarizing the impact of nutrition and diet on breast cancer risk. However, very few consider the implication of genetic background and the effect of personalised nutrition on the risk and prognosis of breast cancer. A literature search was performed using the following databases: MEDLINE (Ovid), PubMed, Scopus and EMBASE (Ovid). The ensuing search terms were selected: genomics, nutrigenomics, breast cancer, breast neoplasms, cancer, nutrigenetics, diet-gene interaction, and Mediterranean, nutrition, polyphenols and diet. In this review, we discuss the Mediterranean-style diet and associated nutrients, evidence of benefit, impact on gene expression and evidence of interactions with genotype and how this interaction can modify breast cancer risk and progression. In addition, the impact of nutrients commonly associated with a Mediterranean-style diet, on breast cancer treatment, and synergistic effects are mentioned when modified by genotype. Some evidence exists around the benefit of a gene-based personalised diet based on a Mediterranean-style dietary pattern, but further evidence in the form of clinical trials is required before such an approach can be comprehensively implemented.

DNA and chromosome damage induced by bleomycin in mammalian cells: An update

Bleomycin (BLM) is an antibiotic isolated from Streptomyces verticillus. It has radiomimetic actions on DNA thus it has been widely used in clinical chemotherapy for the treatment of different types of cancer, including head and neck tumors, lymphomas, squamous-cell carcinomas and germ-cell tumors. Because of this, the study of BLM genotoxicity is of practical interest. This antibiotic is an S-independent clastogen and an agent that generates free radicals and induces single- and double-strand breaks in DNA. In the present review, we will summarize our current knowledge concerning the DNA and chromosome damage induced by BLM in mammalian cells, with emphasis on new developments published since 1991.

Use of Single-cell Gel Electrophoresis Assays in Dietary Intervention Trials

The single-cell gel electrophoresis (SCGE) technique has been frequently used to investigate the impact of consumption of complex foods and individual constituents on DNA stability in humans. Since no division or cultivation of the indicator cells (in most studies lymphocytes) is required, this approach is less costly and time consuming than cytogenetic methods. Apart from single- and double-stand breaks and apurinic sites, which can be detected under standard conditions, it is also possible to assess the formation of oxidized DNA bases and alterations of DNA repair as well as protection of the DNA against chemical carcinogens. In total, 93 studies have been published since the first use of the Comet assay in this field in 1997. The results which emerged from these studies show that human foods contain specific highly protective components (e.g. gallic acid, xanthohumol, isoflavones); promising results were also obtained with beverages (coffee and other drinks), while mixed diets with vegetables and fruits conferred no or moderate protection; however, individual plant foods (e.g. kiwis and specific cruciferous vegetables) were highly protective. It is notable that prevention of DNA damage was rarely detected under standard conditions while evidence for reduced formation of oxidized DNA bases was found in approximately 30% of the trials. In some investigations it was possible to identify the modes of action by which specific compounds prevented damage of the genetic material in additional mechanistic experiments. The currently available data show that SCGE assays are a valuable tool for identifying dietary factors which improve the stability of the genetic material and prevent adverse health effects which are causally related to DNA damage.

Oxidative Stress, Cytotoxicity, and Genotoxicity Induced by Methyl Parathion in Human Gingival Fibroblasts: Protective Role of Epigallocatechin-3-Gallate

Organophosphorous (OP) compounds are pesticides frequently released into the environment because of extensive use in agriculture. Among these, methyl parathion (mPT) recently received attention as a consequence of illegal use. The predominant route of human exposure to mPT is via inhalation, but inadvertent consumption of contaminated foods and water may also occur. The goal of this study was to investigate the in vitro effects of mPT on cells in the oral cavity and evaluate the potential protective role of epigallocathechin-3-gallate (EGCG) on these effects. Human gingival fibroblasts (HGF) were exposed to 10, 50, or 100 μ g/ml mPT for 24 h and assessed for oxidative stress, as evidenced by reactive generation of oxygen species (ROS), induction of apoptotic cell death, DNA damage (comet assay and cytochinesis-block micronucleus test), and nitric oxide (NO) production. The results showed that mPT produced significant oxidative stress, cytotoxicity, and genotoxicity and increased NO levels through stimulation of inducible NO synthase expression. Finally, data demonstrated that EGCG (10, 25, or 50 μ M) was able to inhibit the pesticide-induced effects on all parameters studied. Data indicate that cytotoxic and genotoxic effects may be associated with oxidative stress induced by mPT observed in HGF cultures and that EGCG plays a protective role via antioxidant activities.

Protective effect of (-)-epigallocatechin-3-gallate on capsaicin-induced DNA damage and oxidative stress in human erythrocyes and leucocytes in vitro

The aim of this study is to show that protective effects of the main catechin (-)-epigallocatechin-3-gallate (EGCG) against capsaicin (CAP) induced oxidative stress and DNA damage in human blood in vitro. Superoxide dismutase, catalase, glutathione peroxidase and malondialdehyde (MDA) level were studied in erythrocytes and leucocytes with increased concentrations of CAP. DNA damage in leucocytes was measured by the comet assay. Human blood cells have been administered with doses between 0 and 200 μM of CAP and/or EGCG (20 μM) for an hour at 37 °C. Treatment with CAP alone has increased the levels of MDA and decreased antioxidant enzymes in human blood cells. A significant increase in tail DNA%, mean tail length and tail moment indicating DNA damage has been observed at the highest dose of CAP treatment when compared to controls. Treatment of cells with CAP plus EGCG prevented CAP-induced changes in antioxidant enzyme activities and MDA level and mean tail lenght indicating DNA damage. A significant increase in mean tail lenght was observed at high doses of CAP. These data suggest that EGCG can prevent toxicity to human erythrocytes and leucocytes caused by CAP, only at low doses.

Protective effects of aqueous and ethanol extracts of rosemary on H2O2-induced oxidative DNA damage in human lymphocytes by comet assay

BACKGROUND

Rosemary (Rosmarinus officinalis) possesses various pharmacological properties such as antioxidant, anti-tumorigenesis and anti-mutagenesis activities. In this study, we investigated the possible protective effects of ethanol and aqueous extracts of rosemary on human lymphocyte DNA damage induced by H2O2. The extent of DNA lesions was measured using comet assay.

METHODS

Blood samples were taken from healthy volunteers and lymphocytes were isolated. The lymphocytes were then incubated in aqueous and ethanol extract of rosemary (0.05, 0.1, 0.5, 1 and 2.5 mg/mL) and H2O2 (50, 100 and 200 mM). Lymphocytes were also incubated with a combination of H2O2 (100 mM) with either 1 or 2.5 mg/mL of both extracts for 30 min at 4°C.

RESULTS

Our findings showed that H2O2 treatment led to a significant concentrate-dependent DNA damage in human lymphocyte when compared to respective controls (p<0.001). The DNA damage which was initially occurred as the result of 100 µM H2O2 (Percentage tail DNA 55.1%) was inhibited due to the ethanol extract of rosemary at the doses tested (percentage tail DNA 4.7% and 4.03%). However, the aqueous extract has no effects on H2O2 genotoxicity.

CONCLUSIONS

We suggest that antioxidant constituents in ethanol extract of rosemary can prevent human lymphocytes oxidative DNA damage which is due to its free radical scavenging activity.

Antigenotoxic effects of (-)-epigallocatechin-3-gallate (EGCG), quercetin, and rutin on chromium trioxide-induced micronuclei in the polychromatic erythrocytes of mouse peripheral blood

This study was conducted to investigate the modulating effects of (-)-epigallocatechin-3-gallate (EGCG), quercetin, and rutin on the genotoxic damage induced by Cr(VI) in polychromatic erythrocytes of CD-1 mice. The animals were divided into the following groups: (i) vehicle only; (ii) flavonoids (10 mg/kg EGCG, 100 mg/kg quercetin, 625 mg/kg rutin, or 100-625 mg/kg quercetin-rutin); (iii) Cr(VI) (20 mg/kg of CrO3); and (iv) flavonoids concomitantly with Cr(VI). All of the treatments were administered intraperitoneally (i.p.). The genotoxic damage was evaluated based on the number of micronucleated polychromatic erythrocytes (MN-PCE) obtained from the caudal vein 0, 24, 48, and 72 h after treatment. Groups treated with EGCG and quercetin exhibited no significant statistical changes in induction of MN-PCE. However, CrO3 treatment significantly increased MN-PCE induction 24 and 48 h after injection. Treatment with flavonoids prior to CrO3 exposure decreased MN-PCE induction compared with CrO3 only. The magnitudes of the potency of flavonoids were in the following order: rutin (82%) > quercetin (64%) > quercetin-rutin (59%) and EGCG (44%). The group treated with rutin significantly reduced genotoxic damage in mice treated with Cr(VI) (antioxidant effect). However rutin exerted a marginal genotoxic effect when administered alone (pro-oxidant effect). Our findings suggest protective effects of EGCG, quercetin, and rutin against genotoxic damage induced by Cr(VI).

Positive influence of a natural product as propolis on antioxidant status and lipid peroxidation in senescent rats

Given the importance of oxidative stress associated to aging, it would be interesting to assess the effect of oral supplementation with antioxidant substances capable of diminishing oxidative aggression and free radicals generation associated to this condition. This study investigated the effects of AIN-93 M diet supplemented either with 2 % of propolis, or with 4 % of a natural product obtained from lyophilizate vegetables, selected by its antioxidant properties, in senescent healthy Wistar rats fed ad libitum over 3 months. Propolis supplementation leads to a lower level of glucose and cholesterol concentrations together with a reduction in protein oxidation. Plasma thiobarbituric acid-reactive substance levels were lower in the rats consuming the natural vegetable product and propolis possibly due to its antioxidant components, neutralizing the free radical produced, and thus preventing cellular damage. The results of the present study suggest a synergic effect of overall propolis compounds reducing the oxidative stress and glucose and cholesterol plasma levels associated with aging.

Phlebodium decumanum is a natural supplement that ameliorates the oxidative stress and inflammatory signalling induced by strenuous exercise in adult humans

Strenuous exercise induces muscle damage due to a highly increased generation of free radicals and inflammatory response and therefore, in this type of exercise, it is important to reduce both oxidative stress and inflammation, at least their negative aspects. The purpose of this study was investigate, for the first time, whether a purified, standard water-soluble fraction obtained from Phlebodium decamanum could reduce the over-expression of inflammation and oxidative stress induced by strenuous exercise. The physical test consisted of a constant run that combined several degrees of high effort (mountain run and ultra-endurance), in permanent climbing. Biochemical parameters, oxidative stress and inflammatory mediators were assessed. The results showed that oral supplementation of P. decumanum during high-intensity exercise effectively reduces the degree of oxidative stress (decreased 8-hydroxy-2'-deoxyguanosine and isoprostanes generation, increased antioxidant enzyme activities in erythrocyte and total antioxidant status in plasma). The data obtained also indicate that this supplementation is efficient in reducing the inflammatory response through the decrease of TNF-α and increase of sTNF-RII, but kept the levels of IL-6 and IL-1ra. In conclusion, oral supplementation of P. decamanum extract during high-intensity exercise effectively reduces the degree of oxidative stress and has anti-inflammatory protective effects, preventing the over-expression of TNF-α but keeping the levels and effects of IL-6. These findings provide a basis for similar Phlebodium supplementation for both professional and amateur athletes performing strenuous exercise in order to reduce the undesirable effects of the oxidative stress and inflammation signalling elicited during high-intensity exercise.

Antigenotoxic and antioxidant activities of palmarosa and citronella essential oils

ETHNOPHARMACOLOGICAL RELEVANCE

Essential oils of palmarosa and citronella have been extensively used in ancient Indian and South-east Asian traditional medicines.

AIM OF THE STUDY

These essential oils have been reported to exhibit antimicrobial, anti parasitic effects against bacteria, yeasts, filamentous fungi, and viruses. In the present study the oils were tested for their potential antigenotoxic and antioxidant properties in human lymphocyte cells.

MATERIALS AND METHODS

The antigenotoxic effect on human lymphocyte cells (measurement of cell viability, DNA damage) was studied using trypan blue dye exclusion test, plasmid pBR322 DNA strand scission, and comet assay. Anti-oxidant activity was evaluated by DPPH(+) free radical scavenging and lipid peroxidation assay.

RESULTS

The essential oils showed a good antigenotoxic activity against methyl methanesulphonate (MMS) and hydrogen peroxide. In addition, a significant dose dependent antioxidant activity was observed.

CONCLUSION

Our data provide evidence that support the usage of palmarosa and citronella essential oils in traditional herbal preparations. They can constitute a natural source of a new and safe antioxidant.

Potent protection of gallic acid against DNA oxidation: results of human and animal experiments

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a constituent of plant derived foods, beverages and herbal remedies. We investigated its DNA protective properties in a placebo controlled human intervention trial in single cell gel electrophoresis experiments. Supplementation of drinking water with GA (12.8 mg/person/d) for three days led to a significant reduction of DNA migration attributable to oxidised pyrimidines (endonuclease III sensitive sites) and oxidised purines (formamidopyrimidine glycosylase sensitive sites) in lymphocytes of healthy individuals by 75% and 64% respectively. Also DNA damage caused by treatment of the cells with reactive oxygen species (ROS) was reduced after GA consumption (by 41%). These effects were paralleled by an increase of the activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathion-S-transferase-π) and a decrease of intracellular ROS concentrations in lymphocytes, while no alterations of the total antioxidant capacity (TAC), of malondialdehyde levels in serum and of the urinary excretion of isoprostanes were found. Experiments with rats showed that GA reduces oxidatively damaged DNA in lymphocytes, liver, colon and lungs and protects these organs against γ-irradiation-induced strand breaks and formation of oxidatively damaged DNA-bases. Furthermore, the number of radiation-induced preneoplastic hepatic foci was decreased by 43% after oral administration of the phenolic. Since we did not find alterations of the TAC in plasma and lipid peroxidation of cell membranes but intracellular effects it is likely that the antioxidant properties of GA seen in vivo are not due to direct scavenging of radicals but rather to indirect mechanisms (e.g. protection against ROS via activation of transcription factors). As the amount of GA used in the intervention trial is similar to the daily intake in Middle Europe (18 mg/person/day), our findings indicate that it may contribute to prevention of formation of oxidatively damaged DNA in humans.

The role of antioxidant versus pro-oxidant effects of green tea polyphenols in cancer prevention

Consumption of green tea (Camellia sinensis) may provide protection against chronic diseases, including cancer. Green tea polyphenols are believed to be responsible for this cancer preventive effect, and the antioxidant activity of the green tea polyphenols has been implicated as a potential mechanism. This hypothesis has been difficult to study in vivo due to metabolism of these compounds and poor understanding of the redox environment in vivo. Green tea polyphenols can be direct antioxidants by scavenging reactive oxygen species or chelating transition metals as has been demonstrated in vitro. Alternatively, they may act indirectly by upregulating phase II antioxidant enzymes. Evidence of this latter effect has been observed in vivo, yet more work is required to determine under which conditions these mechanisms occur. Green tea polyphenols can also be potent pro-oxidants, both in vitro and in vivo, leading to the formation of hydrogen peroxide, the hydroxyl radical, and superoxide anion. The potential role of these pro-oxidant effects in the cancer preventive activity of green tea is not well understood. The evidence for not only the antioxidant, but also pro-oxidant, properties of green tea is discussed in the present review.

Assays to determine DNA repair ability

DNA repair is crucial to the integrity of the human genome since mammalian cells are continuously exposed to different chemical and physical genotoxic agents. To counteract the lesions induced by these agents, organisms have developed a number of highly conserved repair mechanisms involving numerous protein complexes grouped in several different repair pathways. The importance of studying the individual capacity to repair DNA damage lies in the observation that deficient repair mechanisms of the genome have been linked to the presence of large number of diseases and cancer, and alterations in these mechanisms may also alter the susceptibility of individuals exposed to a particular mutagen. This review focused on the current knowledge of different assays developed to evaluate DNA repair capacity (DRC). These assays, which are grouped into five major categories, have been successfully applied in (1) in vitro studies, (2) epidemiological studies in patients with cancer or other different pathologies, and (3) environmentally or occupationally exposed populations. Nevertheless, some of the limitations include high interlaboratory variability and difficulty to implement the assays on a large scale. The selection of an adequate DRC assay needs to be made on the basis of the objective raised for its application and taking into account a number of determining factors, namely, (1) speed and cost, (2) type of DNA repair to be evaluated, and (3) sample availability.

Gene expression profiles in human peripheral blood mononuclear cells as biomarkers for nutritional in vitro and in vivo investigations

Identification of chemopreventive substances may be achieved by measuring biological endpoints in human cells in vitro. Since generally only tumour cells are available for such investigations, our aim was to test the applicability of peripheral blood mononuclear cells (PBMC) as an in vitro primary cell model since they mimic the human in vivo situation and are relatively easily available. Cell culture conditions were refined, and the basal variation of gene expression related to drug metabolism and stress response was determined. Results were compared with profiles of an established human colon cell line (HT29) as standard. For biomarker development of nutritional effects, PBMC and HT29 cells were treated with potentially chemopreventive substances (chrysin and butyrate), and gene expression was determined. Key results were that relevant stress response genes, such as glutathione S-transferase T2 (GSTT2) and GSTM2, were modulated by butyrate in PBMC as in HT29 cells, but the blood cells were less sensitive and responded with high individual differences. We conclude that these cells may serve as a surrogate tissue in dietary investigations and the identified differentially expressed genes have the potential to become marker genes for population studies on biological effects.

Prevention of oxidative DNA damage in inner organs and lymphocytes of rats by green tea extract

BACKGROUND

Consumption of green tea (GT) is associated with decreased incidences of specific forms of cancer in humans and it was postulated that its antioxidant (AO) properties may account for these effects. The evidence for AO effects of GT is mainly based on the results from in vitro experiments and on animal studies in which protection against chemically induced damage was monitored.

AIM OF THE STUDY

The goal of the study was the investigation of the prevention of strand breaks and DNA migration attributable to endogenous oxidation of bases by GT extract (GTE) in inner organs and lymphocytes of untreated rats. In addition, immunological parameters and biochemical markers were monitored.

METHODS

DNA migration was measured in hepatocytes, colonocytes and lymphocytes after consumption of a low (1.3 mg/kg bw per day, 5 days) and a high dose (6.5 mg/kg bw per day, 5 days) of GTE in COMET assays (n = 5 animals per group). In addition, immunological parameters (TNF-alpha, IFN-gamma, IL-4 and IL-10), the total AO capacity and oxidized low-density lipoproteins were determined in plasma.

RESULTS

No evidence for reduction in DNA damage was found with a lower dose, whereas with the higher dose, reduction in DNA migration attributable to formamidopyrimidine-DNA-glycosylase sensitive lesions (oxidized purines) and endonuclease III-sensitive sites (oxidized pyrimidines) (58 and 73%) was observed in lymphocytes; also, in colonocytes (reduction in FPG-sensitive sites by 46%) and hepatocytes (decrease in Endo III-sensitive sites by 74%) protective effects were found, while none of the other parameters was altered.

CONCLUSIONS

Our results show that a dose of GTE, which is equivalent to consumption of 500 ml GT/p/day in humans protects lymphocytes and to a lesser extent inner organs against oxidative DNA damage, while no effect was seen with a lower dose corresponding to an uptake of 100 ml/p/day.

50 Hz extremely low frequency electromagnetic fields enhance protein carbonyl groups content in cancer cells: effects on proteasomal systems

Electromagnetic fields are an assessed cause of prolonging free radicals lifespan. This study was carried out to investigate the influence of extremely low frequency electromagnetic fields on protein oxidation and on the 20S proteasome functionality, the complex responsible for the degradation of oxidized proteins. Caco 2 cells were exposed, for 24-72 hours, to 1 mT, 50 Hz electromagnetic fields. The treatment induced a time-dependent increase both in cell growth and in protein oxidation, more evident in the presence of TPA, while no changes in cell viability were detected. Exposing the cells to 50 Hz electromagnetic fields caused a global activation of the 20S proteasome catalytic components, particularly evident at 72 hours exposure and in the presence of TPA. The finding that EGCG, a natural antioxidant compound, counteracted the field-related pro-oxidant effects demonstrates that the increased proteasome activity was due to an enhancement in intracellular free radicals.

Antioxidative and anti-carcinogenic activities of tea polyphenols

Tea (Camellia sinensis, Theaceace), a popular beverage consumed world-wide, has been studied for its preventive effects against cancer as well as cardiovascular, neurodegenerative, and other diseases. Most of the proposed beneficial effects have been attributed to the polyphenolic compounds in tea, but the nature of these activities and the molecular mechanisms of their actions remain unclear. Tea polyphenols are known to be strong antioxidants. Prevention of oxidative stress, modulation of carcinogen metabolism, and prevention of DNA damage have been suggested as possible cancer preventive mechanisms for tea and tea polyphenols. In this chapter, we discuss these topics in the light of biotransformation and bioavailability of tea polyphenols. We also review the preventive effects of tea polyphenols in animal models of carcinogenesis and some of the possible post-initiation mechanisms of action. Finally, we discuss the effects of tea consumption on cancer risk in humans. It is our aim to raise some of the unanswered questions regarding cancer prevention by tea and to stimulate further research in this area.

Direct in vivo evidence of protective effects of grape seed procyanidin fractions and other antioxidants against ethanol-induced oxidative DNA damage in mouse brain cells

Ethanol is a principle ingredient of alcoholic beverages with potential neurotoxicity and carcinogenicity, and the ethanol-associated oxidative DNA damage in the central nervous system is well documented. The present work studied the possible protective effects of grape seed oligomer and polymer procyanidin fractions against ethanol-induced toxicity and compared these with resveratrol and other well-known antioxidants (ascorbic acid and vitamin E). By using the single cell gel electrophoresis (comet assay), a simple and sensitive technique for genotoxicity studies, the potential genotoxicity of acute and chronic ethanol administration in the different brain regions was investigated. Acute ethanol administration, at the dose of 2.5 or 5.0 g kg(-1) i.p., could induce significant DNA damage in cerebellum and hippocampus. Chronic administration of ethanol at the dose of 2.5 or 5.0 g kg-1 p.o. for 30 days could induce significant DNA damage in cerebellum, hippocampus, hypothalamus, and cortex, which could be auto-repaired at least 3 days after ethanol withdrawal. Oral administration of grape seed oligomer and polymer procyanidins and resveratrol (25, 50, and 100 mg kg(-1)) for 3 days before acute ethanol (5.0 g kg(-1), i.p.) or repeated administration of these substances together with ethanol (5.0 g kg(-1), p.o.) for 30 consecutive days could significantly inhibit DNA damage in brain cells induced by ethanol. As compared, ascorbic acid (50, 100, and 200 mg kg(-1)) and vitamin E (100, 200, and 400 mg kg(-1)) could also present protective effects on ethanol-induced DNA damage. Furthermore, the concentrations of ethanol and acetaldehyde in brain regions of the mice were detected by gas chromatography after administration of ethanol plus antioxidants. All of the results indicated that ethanol could induce region-specific oxidative DNA damage in which the cerebellum and hippocampus were more vulnerable, but intake of grape seed procyanidins or other natural antioxidants could protect the brain against ethanol-induced genotoxicity.

Naringin, a grapefruit flavanone, protects V79 cells against the bleomycin-induced genotoxicity and decline in survival

The effect of naringin, a grapefruit flavonone was studied on bleomycin-induced genomic damage and alteration in the survival of cultured V79 cells. Exposure of V79 cells to bleomycin induced a concentration dependent elevation in the frequency of binucleate cells bearing micronuclei (MNBNC) and a maximum number of MNBNCs were observed in the cells treated with 50 microg ml(-1) bleomycin, the highest concentration evaluated. This genotoxic effect of bleomycin was reflected in the cell survival, where a concentration dependent decline was observed in the cells treated with different concentrations of bleomycin. Treatment of cells with 1 mm naringin before exposure to different concentrations of bleomycin arrested the bleomycin-induced decline in the cell survival accompanied by a significant reduction in the frequency of micronuclei when compared with bleomycin treatment alone. The cell survival and micronuclei induction were found to be inversely correlated. The repair kinetics of DNA damage induced by bleomycin was evaluated by exposing the cells to 10 microg ml(-1) bleomycin using single cell gel electrophoresis. Treatment of V79 cells with bleomycin resulted in a continuous increase in DNA damage up to 6 h post-bleomycin treatment as evident by migration of more DNA into the tails (% tail DNA) of the comets and a subsequent increase in olive tail moment (OTM), an index of DNA damage. Treatment of V79 cells with 1 mm naringin reduced bleomycin-induced DNA damage and accelerated DNA repair as indicated by a reduction in % tail DNA and OTM with increasing assessment time. A maximum reduction in the DNA damage was observed at 6 h post-bleomycin treatment, where it was 5 times lower than bleomycin alone. Our study, which was conducted on the basis of antioxidant, free radical scavenging and metal chelating properties of naringin demonstrates that naringin reduced the genotoxic effects of bleomycin and consequently increased the cell survival and therefore may act as a chemoprotective agent in clinical situations.

Intervention with polyphenol-rich fruit juices results in an elevation of glutathioneS-transferase P1 (hGSTP1) protein expression in human leucocytes of healthy volunteers

Polyphenols are probably antigenotoxic on account of their antioxidant activities and might alter phase I and II enzymes in a way that results in chemoprotection. We investigated the hypothesis that polyphenols enhance expression of glutathione S-transferases (GSTs), which increases carcinogen detoxification and thereby provides protection against oxidative stress. HGSTP1 protein expression and GST polymorphisms were determined in leucocytes obtained during an intervention study with healthy subjects consuming two fruit juices in an 8 wk trial (polyphenol-free run in phase, juice intervention phase, washout phase, second juice intervention phase, each treatment regime lasted for 2 wk). The study had originally shown that juice intervention significantly reduced oxidative DNA damage in leucocytes at week 8 (Bub, A., Watzl, B., Blockhaus, M., Briviba, K. et al., J. Nutr. Biochem. 2003, 14, 90-98). We reanalysed the levels of DNA damage based on GST genotypes. We also treated leucocytes in vitro with mixtures of polyphenols and determined cytotoxicity and expression of 96 genes related to drug metabolism. Key results with leucocytes of the intervention study were that the initial content of hGSTP1 protein was first suppressed at weeks 4 and 6. At week 8, however, hGSTP1 protein expression was significantly increased. HGSTP1 protein levels and DNA damage were inversely correlated (p = 0.005), but there was no difference for cells obtained from subjects with hGSTM1*1 and hGSTM1*0 genotypes, nor was there any difference between cells from subjects consuming the two different juices. The treatment of leucocytes with polyphenol mixtures in vitro did not result in modulated GST gene expression or total GST activity, but in an up-regulation of other biotransformation enzymes (e. g., members of the cytochrome P450 and the sulphotransferase family). In conclusion, in vitro treatment of leucocytes led to a modulated mRNA expression of selected genes, not directly related to oxidative defence systems. In vivo, however, we observed a delayed enhancement of hGSTP1, which could be associated with an initial repression of oxidative DNA damage in leucocytes from human subjects, consuming juices with high levels of polyphenols.

Both wheat (Triticum aestivum) bran arabinoxylans and gut flora-mediated fermentation products protect human colon cells from genotoxic activities of 4-hydroxynonenal and hydrogen peroxide

Dietary fibers are fermented by the gut flora to yield short chain fatty acids (SCFAs), which inhibit the growth of tumor cells, induce glutathione S-transferases (GSTs), and protect cells from the genotoxic activity of 4-hydroxynonenal (HNE). Here, we investigated effects of wheat bran-derived arabinoxylans and fermentation products on these parameters of chemoprevention. Newly isolated water extractable (WeAx) and alkali extractable arabinoxylans (AeAx) were fermented under anaerobic conditions with human feces. Resulting fermentation supernatants (FSs) were analyzed for SCFAs and used to treat HT29 colon cancer cells. Cell growth, cytotoxicity, antigenotoxicity against hydrogen peroxide (H2O2) or HNE, and GST activity were determined. Nonfermented WeAx decreased H2O2-induced DNA damage by 64%, thus demonstrating chemoprotective properties by this nonfermented wheat bran fiber. The fermentation of WeAx and AeAx resulted in 3-fold increases of SCFA, but all FSs (including the control without arabinoxylans) inhibited the growth of the HT29 cells, reduced the genotoxicity of HNE, and enhanced the activity of GSTs (FS WeAx, 2-fold; FS AeAx, 1.7-fold; and control FS, 1.4-fold), which detoxify HNE. Thus, increases in SCFAs were not reflected by enhanced functional effects. The conclusion is that fermentation mixtures contain modulatory compounds that arise from the feces and might add to the effectiveness of SCFAs.