PROTECTIVE ACTION OF DIFFERENT NATURAL FLAVAN3OLS AGAINST AFLATOXIN B 1 RELATED CYTOTOXICITY

jfbc_301 595..610

PROTECTIVE ACTION OF DIFFERENT NATURAL FLAVAN-3-OLSAGAINST AFLATOXIN B1-RELATED CYTOTOXICITY

CORNELIA BRAICU1,2,4, DUMITRITA RUGINA2,VERONICA SANDA CHEDEA2, OANA TUDORAN1, OVIDIU BALACESCU1,

IOANA NEAGOE1,3 and CARMEN SOCACIU2

1Cancer Institute “I Chiricuta”34–36 Republicii st. 400015

2University of Agricultural Sciences and Veterinary Medicine

3University of Medicine and Pharmacy “Iuliu Hatieganu”Cluj-Napoca, Romania

Accepted for Publication August 21, 2008

ABSTRACT

The aim of this study is to investigate the ability of flavan-3-ols: catechin,epigallocatechin, epigallocatechin gallate, and epicatechin gallate to preventaflatoxin B1 (AB1)-induced cytotoxicity in A2780 cell line. The treatment withAB1 (0.35 mM) gives an increased level of cytotoxicity versus control (30–50%). Flavan-3-ols are more efficient against AB1 cytotoxicity at 24 h aftertreatment than after 48 h. AB1-induced dichlorofluorescin diacetate fluores-cence intensity was significantly reduced even after 1 h incubation withflavan-3-ols. Concerning the tumor necrosis factor-alpha (TNF-a) release,comparing with the control, AB1 induces a down-expression of this factor. Allthe flavan-3-ols induced a higher level of TNF-a release in the cellularsupernatant comparing with the AB1 group, but much lower than the controlgroup. The present study demonstrates the potent protective effect of flavan-3-ols against AB1 cytotoxicity in A2780 epithelial cell line. This protectiveeffect may be due to the inhibitory effect of flavan-3-ols on AB1-inducedreactive oxygen species formation and oxidative damage.

PRACTICAL APPLICATIONS

There is a delicate balance between antioxidants and pro-oxidants, gen-erally and specifically, in the cell. They are responsible for regulation of

4 Corresponding author. TEL: +0040-264-595825, 596384(5,6,7) ext. 213; FAX: +0040-264-593792;EMAIL: [email protected]

DOI: 10.1111/j.1745-4514.2009.00301.x

Journal of Food Biochemistry 34 (2010) 595–610.© 2010, The Author(s)Journal compilation © 2010, Wiley Periodicals, Inc.

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various metabolic pathways, immunosuppression, growth and developmentand protection against stress. Mycotoxins have negative impact on thisantioxidant/pro-oxidant balance. This balance can be regulated by dietaryantioxidants like flavan-3-ols.

There are various approaches to control or combat mycotoxin problems;one is by developing new oxidant strategies by improving the natural defensemechanism against mycotoxins at cellular level.

Considering the role of reactive oxygen species in chemically inducedcarcinogenesis, the ability of aflatoxins to induce cytotoxicity to cells may playan important role in aflatoxin-induced carcinogenicity. Chemopreventive strat-egies designed to limit the several toxic effects, caused by these mycotoxins,are important public health goals for reducing the incidence of aflatoxin-induced diseases. Flavan-3-ols, a class of phenolic compounds ubiquitous inplants and widely found in a number of fruits, vegetables and beverages, canbe a choice of preventing the mycotoxin-related toxicity as we reported in thisstudy.

INTRODUCTION

Aflatoxins are toxic secondary metabolites of Aspergillus sp., such A.parasiticus, and A. flavus. Aflatoxins have been shown to cause toxicity foranimals and humans (Eaton and Gallagher 1994; Yang et al. 2000; Bennett andKlich 2003). Due to their high-toxicity aflatoxins, special aflatoxin B1 (AB1)has received greater attention than other mycotoxins (Bennett and Klich 2003).

Aflatoxins in vitro/in vivo can generate free radicals decreasing the anti-oxidant protection, causing lipid peroxidation and damage to other biologicalmolecules including lipids, proteins and DNA (Wogan 1999; Verma 2004).This could lead to antioxidant/pro-oxidant imbalance causing oxidative stresswhich further leads to cytotoxic and genotoxic effects of aflatoxins.

The mechanism of action of aflatoxins involves their metabolism toreactive oxygen species (ROS) which bind to nucleic acids and proteins withconsequent disruption of transcriptional and translational processes (Wogan1999; Verma 2004). Although it has been well established that the formation ofAB1-8, 9-epoxide and its subsequent binding to DNA to form AB1-DNAadducts are critical steps to its carcinogenesis, the mechanism of AB1 has notbeen fully elucidated (Eaton and Gallagher 1994; Wogan 1999; Yang et al.2000; Verma 2004; Guerra et al. 2005). The immunotoxic potential of afla-toxins was reported in many species and in vitro models (Oswald and Comera1998; Bondy and Pestka 2000; Marin et al. 2002; Bouhet and Oswald 2005).Aflatoxins are immunosuppressive in a variety of animals, making them more

596 C. BRAICU ET AL.

susceptible to infection by various microorganisms (Jakab et al. 1994). Lowdoses of aflatoxins manifest their effects on other immune parameters such ascytokines.

Flavan-3-ols and its derivatives are a class of phenolic compounds presentin green tea leaves, chocolate, grape and grape seeds. They have shown severalhealthy properties. Among them are anticancer properties (Cooper et al. 2005;Yang et al. 2005) and a protective capacity against oxidative stress-relateddiseases (Erba et al. 2005; Hsu 2005). Antioxidative properties of flavan-3-olsare manifested particularly by their abilities to upregulate the antioxidantenzymes (Khan et al. 1988), and to scavenge the ROS (Rice-Evans et al.1996). An antioxidant supplementation may protect against cytotoxic effect oftheir aflatoxins by interfering in one of the several steps of their mechanism ofaction. The aim of this study is to evaluate the ameliorative effect of flavan-3-ols on AB1-induced cytotoxicity, the ability of flavan-3-ols to scavenge freeradicals generated by AB1 and evaluating tumor necrosis factor-alpha (TNF-arelease in the presence of flavan-3-ols and/or AB1.

Studies in our laboratory have shown that AB1 caused an increased levelof cytotoxicity in different in vitro models, and also an increased level of ROS(Braicu et al. 2009a,b). The capacity of catechin (C), epigallocatechin (EGC),epigallocatechin gallate (EGCG), and epicatechin gallate (ECG) to preventAB1-induced cytotoxicity was tested on A2780 cell line. A2780 is a humanovarian cancer cell line from epithelial origin widely used for toxicology tests(Bellarosa et al. 2001; Messori et al. 2004). Cytotoxicity was studied using the3-(4, 5) dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay(Otoguro et al. 1991; Neradil et al. 2003; Lindl et al. 2005), detection of ROSwas done using a fluorimetric method (Yang et al. 2000) and TNF-a releasewas determined using an immunoassay method.

MATERIALS AND METHODS

Chemicals

(-) C, (-) EGC, (-) EGCG, (-)ECG, 2′7′-dichlorofluorescin diacetate(DCFH-DA), AB1 and MTT ((3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetra-zolium bromide) and AB1 were purchased from Sigma-Aldrich, Bucuresti,Romania, while Quantikine TNF-a Immunoassay kit was purchase fromRedox, Cluj-Napoca, Romania.

Cell Culture

A2780 cells (epithelial human ovarian cancer cell line), were routinelyincubated in a humidified 5% CO2–95% air mixture at 37C. Cells were culti-

597PROTECTIVE EFFECT OF FLAVAN-3-OLS AGAINST AFLATOXINS CYTOTOXICITY

vated in RPMI 1640 (Sigma-Aldrich) supplemented with 10% fetal bovineserum (Sigma-Aldrich), 2 mM glutamine, 100 UI/mL penicillin and100 mg/mL streptomycin (Sigma-Aldrich).

Cell Treatment

The effect of flavan-3-ols on AB1-induced oxidative damage was testedby treating cells with 0.35 mM AB1 and different concentrations (12.5, 25, 50,125 mM) of flavan-3-ols (C, EGC, EGCG, ECG), doses that have no significanteffect on cell proliferation and viability at 24 and 48 h. TNF-a release wasmeasured after 24 h of treatment. The effect of AB1-induced ROS was testedin the presence or absence of flavan-3-ols up to 4 h.

Determination of Cell Viability

The cytotoxicity of AB1 on A2780 cells was evaluated by MTT assay,using suspension of 2 ¥ 103 cells per well in 96 well plates. After 24 h, whilein logarithmic growth cell phase, cells were treated with AB1 with/withoutflavan-3-ols. MTT assay was performed after 24 and 48 h, respectively, aftertreatment (Otoguro et al. 1991; Lindl et al. 2005).

In order to perform the MTT assay, the culture medium was removed;cells were washed with phosphate buffered saline and 150 mL Hanks saltcontaining MTT (Sigma) at the final concentration of 455 mg of MTT permilliliter of Hanks salt were added into each well. After 2 h incubation understandard conditions, the MTT solution was removed and 20 mL of dimethylsulfoxide were added into each well. Absorbance was measured at 490 nmusing a Biotek Synergy HT Microplate Plate Reader (BioTek Instruments,Bucharest, Romania; Otoguro et al. 1991; Neradil et al. 2003; Lindl et al.2005).

Detection of Intracellular ROS

Intracellular ROS were quantified by using a fluorescent probe 2′7′-dichlorofluorescin diacetate (DCFH-DA) (Yang et al. 2000). DCFH-DA dif-fuses thought the cell membrane readily and is enzymatically hydrolyzed byintracellular esterases to nonfluorescent dichlorofluorescin diacetate (DCFH-DA), which is rapidly oxidized to highly dichlorofluorescin (DCF) in thepresence of reactive species formed intracellular (Yang et al. 2000).

Cells were seeded in 96 well black plates, 2 ¥ 103 cells per well, andallowed to grow for 24 h. After that, the cells were treated with variousconcentrations of flavan-3-ols in the presence of AB1 and of DCFH-DA (finalconcentration 0.1 mM). DCF fluorescence intensity was detected at different


time intervals using a Biotek Synergy HT Microplate Plate Reader with anexcitation wavelength measured at 485 nm and emission wavelength at530 nm.

Enzyme-linked Immunosorbent Assay for Human TNF-a

The TNF-a immunoassay analysis was performed according to the manu-facturer’s recommended protocol. Cells were seeded at 2 ¥ 103 cells per wellin 96 well plates. Immunoassay for TNF-a was performed after 24 h oftreatment. The supernatant was centrifuged to remove cell debris and stored at-70C until assayed. Preliminary assays were performed to determine theoptimal dilution of supernatant; each determination was made in triplicate andis expressed as average of three determinations.

Statistical Analysis

Data are presented as means � standard deviation. The differencesamong different groups were analyzed using one-way analysis of variancewith t-test. A P value of less than 0.05 was considered statistically significant.

RESULTS

The evaluation of mycotoxins on epithelial cells may explain the patholo-gies observed at animals and human, especially to see the relation betweentoxicity and innate and adaptive components of immunity (Bouhet and Oswald2005). We already tested the effect of AB1 on cell cultures and the results fromour preliminary experiments demonstrated that AB1 was able to induce dose-dependently cell injury in A2780 cell line (Braicu et al. 2008). As a result ofprevious experiments, we have chosen the concentration of 0.35 mM AB1 forall subsequent tests presented in this article.

Effect of Flavan-3-Ols on AB1 by Measuring Cell Viability UsingMTT Assay

The effect of concentration of different flavan-3-ols (C, EGC, EGCG,ECG) (12.5, 25, 50, 125 mM) on AB1 (0.35 mM)-induced cytotoxicity at 24 and48 h is presented in Fig. 1. The treatment with AB1 gives an increased level ofcytotoxicity versus control (untreated cells) (30–50%).

EGCG and ECG were the most efficient in protecting cells from AB1-induced cell toxicity, at 24 h after treatment. For all flavan-3-ols tested, weobserved a good relationship dose–effect; the cytotoxicity caused by AB1 wasreduced by all the tested flavan-3-ols and at all doses. At 48 h, the protective


effect of ECGC, ECG and EGC is lower compared with the value observed at24 h; for C, the values observed for MTT remain relatively constant at 24 and48 h. Loss of cell viability was time dependent; after 48 h of exposure to AB1,the MTT values were lower than after 24 h.

From Fig. 1, it can be observed that at 24 h, EGCG and EGC have the bestanticytotoxicity action, and at 48 h, only EGC has the highest MTT value. Thisfact can be explained by the structural features of the different flavan-3-olstaken for this study. EGCG and ECG contain both gallate groups at position 3(Fig. 2). EGCG contains an –OH group more ECG at position 5′not presentedin the case of ECG. As a difference between ECG and EGCG on one side andthe C and EGC on the other side, it is given by the gallate group that we can

FIG. 1. EFFECT OF FLAVAN-3-OLS ON AFLATOXIN B1 (AB1)-INDUCED CYTOTOXICITYUSING MTT ASSAY AT 24 H EXPOSURES AND 48 H EXPOSURES

Cells were incubated with AB1 (0.35 mM) and or/flavan-3-ols (12.5–125 mM) on A2780 cell line;(A) at 24 h, (B) at 48 h, MTT assay was performed. Data are presented as mean � standard

deviation (n = 6), (*P < 0.05 compared to the control and #P < 0.05 compared to the group treatedwith aflatoxin B1 using one-way analysis of variance with t-test).


suppose that at 24 h, the treated cells with EGCG and ECG give the bestprotective effect against AB1 cytotoxicity activity due to this gallate. At 48 h,only ECG maintains its highest protective effect against AB1 cytotoxicity,although lower than at 24 h. Here, we can assume that in 48 h, EGCG isoxidized at the –OH group from position 5′. This is transformed in ECG, solevels of this flavan-3-ol are registered for the MTT test at 48 h.

The protective effects of flavan-3-ols on AB1 levels of cytotoxicity areevident especially after 24 h of incubation with AB1. This may be due to theirantioxidants properties. Such antioxidants are particularly known to be effec-tive in scavenging peroxyl and alkoxyl radicals, thus preventing the propaga-tion of lipoperoxidation (Luczay and Skrzydlewska 2005; Costa et al. 2007).Consequently, oxidation of other important macromolecules as enzymes, andDNA, are reduced. Cell apoptosis is reduced as shown in cytotoxicity data(Fig. 1) directly by flavan-3-ols or indirectly by their metabolic products.

These results demonstrate that flavan-3-ols may have significant inhibi-tory effects on metabolic transformation of AB1 to their toxic or carcinogenicderivatives. Alternatively, they may promote their transformation into lesstoxic or even nontoxic products. Flavan-3-ols are acting efficient on reducingAB1 cytotoxicity at 24 h, but at 48 h, flavan-3-ols are less efficient than at 24 h.This may suggest that metabolites involved in detoxification processes mayplay an important role on AB1 toxicity.

FIG. 2. CHEMICAL STRUCTURES OF FLAVAN-3-OLS TAKEN IN THIS STUDY


Effect of Flavan-3-Ols on AB1-induced Intracellular ROS

The effect of various concentration of flavan-3-ols (C, EGC, EGCG,ECG) in the presence of AB1-induced ROS formation on A2780 cell line arepresented in Fig. 2. A single dose of AB1 (0.35 mM) was able to induce asignificant increase of ROS concentration compared with control group(P < 0.05); this dose was used to analyze the protective effect of EGCG, EGC,ECG and C on AB1-induced ROS production. In particular, the production ofROS was decreased, compared with the cells treated with AB1 alone. AB1-induced DCF fluorescence intensity was significantly reduced even for 1 h ofincubation with flavan-3-ols. Observations showed that control group for thefluorescence intensity increased steadily (Fig. 2), suggesting that ROS areformed spontaneously on A2780 cell line. Nevertheless, a significant inhibi-tory effect, with a dose–effect relationship, was noted in the case of treatmentwith flavan-3-ols; no pro-oxidant effect was observed.

It is well recognized that oxidative stress generates ROS that are capableof damaging mammalian cells. The stronger inhibitory action of EGCG andECG than EGC and C on AB1-induced toxicity is likely to be attributed to theirhigher antioxidant power. Less efficient was EGC and C on AB1-inducedtoxicity due to their lower antioxidant capacity as determined by Rugina et al.(2007).

A possible mechanism of cytotoxicity prevention might be the inhibitionof enzymes, which activate the aflatoxins and the activation of detoxificationenzymes (Hockenbery et al. 1993; Luczay and Skrzydlewska 2005). The roleof flavan-3-ols in producing a coordinate modulation of multiple-enzymecarcinogen detoxification should not be underestimated. It was also shown thatregulation of both basal and inducible expression of cytoprotective genes ismediated in part by the antioxidant response element (Costa et al. 2007).

Intracellular ROS generation was detected in the case of AB1 and wasrepressed by the flavan-3-ols. The presented results strongly indicated thatflavan-3-ols protect cells from AB1 toxicity. Higher concentrations of C inhibitthe intracellular ROS formation. After 4 h of incubation, the DCF fluorescenceintensity dropped for the C and ECG, and had decreased for ECGC and ECG.This situation may be explained by the fact that the protection enzymes areactivated faster in the case of C and ECG in the presence of AB1 and are lessefficient in the case of EGCC and EGC.

ROS are thought to play a major role in apoptosis (Hockenbery et al.1993; Ratan et al. 1994). For example, in the case of AB1 treatment ROS frommitochondria; it can cause apoptosis GSH by depletion (Zucker et al. 1997;Meki et al. 2001). Therefore, apoptosis is induced by oxidative damage(caused by AB1) either from reactive species that generate in cells or by AB1

as an injury agent. Intracellular induction of apoptosis by intrinsic mechanism


can be efficiently blocked by antioxidants (Yang et al. 2000). This may also bea possible explanation of a higher cellular viability in the case of treatmentwith flavan-3-ols.

AB1-induced ROS was partially inhibited by flavan-3-ols treatments(Fig. 3). The protective effect against the cytotoxicity was not so efficient,especially at 48 h (Fig. 1), suggesting that the aflatoxins and flavan-3-olsmetabolites products may also play an important role in cytotoxicity. This wasalso suggested also by Yang et al. (2005) in a similar study focused on theevaluation of the protective effect of a synthetic seleno-organo compoundagainst AB1 cytotoxicity.

Stimulating Effect of Flavan-3-ols on AB1 on TNF-a Expression

TNF-a release was measured after 24 h of treatment in the presence offlavan-3-ols: EGCG, EGC, ECG and C at the following mM doses, 12.5, 25.0,50.0, 125 and/or AB1. The effect of flavan-3-ols on AB1 to modulate TNF-asecretion is presented in Fig. 4.

Differences of TNF-a levels were observed; in the case of AB1, we havedown-expression of TNF-a (98.9 pg/mL) compared with the control group(127.5 pg/mL). All the flavan-3-ols induced a higher level of TNF-a secretionin the cellular supernatant compared with the AB1 group, but much lower thanthe control group.

The concentration of 12.5 mM of EGCG and EGC was observed at thehigher level of TNF-a (115 and 108.3 pg/mL, respectively), which is higherthan the other flavan-3-ols doses tested. Our results concerning the TNF-aexpression are in agreement with Marin et al. (2002) who sustain thatAB1 induced a decreased level of pro-inflammatory and increasedanti-inflammatory cytokine mRNA expression in weanling piglets. TNF-asignaling pathways suggest its involvement on toxicity mechanism. Aflatoxin-induced apoptosis pathways associated with an increased level of caspase-3activity (Meki et al. 2001) and with down-expression of effectors like TNF-a(Gopee and Sharma 2004). An increased level of TNF-a in the case of flavan-3-ols treatment may be a result of interference in cellular regulatory mecha-nism of translation and transcription.

AB1 is transformed in vivo into active metabolites that bind to DNA andRNA and inhibit RNA and protein synthesis. Inhibition of DNA, RNA andprotein synthesis directly and indirectly impairs the continual proliferation anddifferentiation of cell and the synthesis of cytokines that regulate the commu-nication network of the immune system (Bellarosa et al. 2001; Marin et al.2002; Gopee and Sharma 2004). TNF-a exists as a membrane-anchored andsoluble form, both of which show biological activity. Down-expression ofTNF-a plays an important role in the pathophysiological processes such as


A

B

C

D

FIG. 3. TIME-RELATED AND DOSE-RELATED EFFECT OF FLAVAN-3-OLS (12.5–125 mM),(A) EPIGALLOCATECHIN GALLATE (EGCG); (B) EPIGALLOCATECHIN (EGC); (C)

CATECHIN (C); (D) EPICATECHIN GALLATE (ECG); IN THE PRESENCE OF AFLATOXINB1 (AB1) (0.35 mM) ON REACTIVE OXYGEN SPECIES AS MEASURED BY FLUORESCENCE

2′7′-DICHLOROFLUORESCIN DIACETATE INTENSITYData are presented as mean � standard deviation, (n = 6), (P < 0.05 compared to the control but

also compared to the group treated with AB1 only using one-way analysis of variance with t-test).


susceptibility to infection by intracellular pathogens induced by aflatoxins andother mycotoxins. Flavan-3-ols, by increasing the level of TNF-a, can reducethe immunosuppressive effect caused by aflatoxins.

TNF-a is known as a survival factor and its synthesis can be regulatedby dual mechanism: (1) due NF-kB that sustain cellular growth; and (2)thought caspase pathways that induce apoptosis (Russo and Polosa 2005). Asshown in Fig. 4, low doses of flavan-3-ols were proven to be an activator ofTNF-a signal transduction and transcription when higher doses of flavan-3-ols were less efficient. Suganuma et al. suggested that EGCG may be thetranscription factor critically involved in the action of various growth factorsand cytokine. From our knowledge, there are no other similar studies thatpresent the expression of TNF-a in the presence of different standards offlavan-3-ols and AB1.

More studies are needed to understand mechanisms and signaling path-ways of upregulation of TNF-a in the case of treatment of flavan-3-ols in thepresence of AB1. A possible signaling pathway in the upregulation of TNF-aseems to be directly linked to regulation of NF-kB and may play an importantrole on mediating release of TNF-a in the presence of flavan-3-ols, sincereducing the level of ROS seems to be related to the mitochondrial pathwaysand apoptosis.

In a recent study, it has been reported that EGCG exerted a biphasic modeof action as a function of concentration (Costa et al. 2007). The low concen-trations are responsible for the anti-apoptotic actions of EGCG (Levites et al.

FIG. 4. QUANTIFICATION OF TUMOR NECROSIS FACTOR-ALPHA (TNF-a) PRODUCTIONFROM CELLULAR SUPERNATANT, IN THE PRESENCE OF FLAVAN-3-OLS

(EPIGALLOCATECHIN GALLATE [EGCG], EPIGALLOCATECHIN [EGC], EPICATECHINGALLATE [ECG] and CATECHIN [C], 12.5–125 mM) AND/OR AFLATOXIN B1 (AB1)

*P < 0.05 compared to the control and #P < 0.05 compared to the group treated with aflatoxin B1

only using one-way analysis of variance with t-test.


2002; Mande et al. 2005). This receives further recognition from an experi-ment employing customized cDNA microarray designed to clarify the molecu-lar mechanisms involved in the cell survival action of EGCG (Levites et al.2002; Mande et al. 2005). Similar results were obtained also in our case; thismay explain the higher level of TNF-a obtained at low concentration of EGCGand EGC. At the same time, higher doses of flavan-3-ols may induce apoptosisacting in a synergistic manner with the aflatoxins triggering the apoptoticcascade. The same idea was presented in another study focused on the effectsof red wine on ochratoxin A using as in vitro model epithelial cells (Ranaldiet al. 2007).

CONCLUSIONS

Because the occurrence of aflatoxins in food and feed is frequent, sub-stances able to reduce effects could be of great interest. Therefore, naturalantioxidant supplements seem to be an attractive strategy to protect humansand animals from the risk of liver and kidney cancer caused by mycotoxins(Storz et al. 2000; Suganuma et al. 2000; Guerra et al. 2005; Hundhausenet al. 2005).

In summary, the present studies demonstrate the potent protective effectof flavan-3-ols against AB1 cytotoxicity in A2780 epithelial cell line. Thisprotective effect may be due to the inhibitory effect of flavan-3-ols on AB1-induced ROS formation and oxidative damage. This may be due to the pre-vention of the alteration of cellular e redox state by flavan-3-ols, and this alsotriggers changes in signaling pathways and subsequent gene expression. Thepresent study using as end points the MTT assay, ROS inhibition and TNF-arelease suggests that different metabolic pathways are triggered by the flavan-3-ols acting as protective agents against AB1-induced cytotoxicity. Furtherstudies should be done in order to evaluate the effect of flavan-3-ols on thegenotoxicity of AB1.

Development of new oxidant strategies by improving the natural defensemechanism may be an important method for inhibiting AB1/mycotoxins tox-icity. Because the early activation signaling pathways as response to aflatoxinsmay be involved in the inflammatory reactions, ROS generation, cytotoxicity,genotoxicity and carcinogenicity, the use of flavan-3-ols as antioxidants mayprove to be beneficial for protecting against mycotoxins contamination in thehuman population.

ACKNOWLEDGMENT

This work was partially supported by a grant from Romania NationalUniversity Research Council, project TD 233/2007.


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PROTECTIVE ACTION OF DIFFERENT NATURAL FLAVAN3OLS AGAINST AFLATOXIN B 1 RELATED CYTOTOXICITY

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