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Ochratoxin A (OTA) is one of the most abundant food-contaminating mycotoxins world wide, and is detrimental to human and animal health. This study evaluated the protective effect of quercetin against OTA-induced cytotoxicity, genotoxicity, and inflammatory response in lymphocytes. Cytotoxicity determined by MTT assay revealed IC20 value of OTA to be 20 µM, which was restored to near control values by pretreatment with quercetin. Oxidative stress parameters such as antioxidant enzymes, LPO and PCC levels indicated that quercetin exerted a protective effect on OTA-induced oxidative stress. Quercetin exerted an antigenotoxic effect on OTA-induced genotoxicity, by significantly reducing the number of structural aberrations in chromosomes and comet parameters like, % olive tail moment from 2.76 ± 0.02 to 0.56 ± 0.02 and % tail DNA from 56.23 ± 2.56 to 12.36 ± 0.56 as determined by comet assay. OTA-induced NO, TNF-α, IL-6, and IL-8 were significantly reduced in the quercetin pretreated samples indicating its anti-inflammatory role. Our results demonstrate for the first time that quercetin exerts a cytoprotective effect against OTA-induced oxidative stress, genotoxicity, and inflammation in lymphocytes. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 855-865, 2016.

BACKGROUND AND PURPOSEOxidative stress and subsequent activation of inflammatory responses is a widely accepted consequence of exposure to environmental toxins. TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), a well-known environmental toxin, exerts its toxicity through many signalling mechanisms, with liver being the principal organ affected. However, an effective antidote to TCDD-induced toxicity is unknown. The present study evaluated the effect of eicosapentaenoic acid (EPA), an n3 fatty acid, on TCDD-induced toxicity. EXPERIMENTAL APPROACHIn cultures of HepG2 cells, the EPA/AA ratio was determined using gas chromatography, oxidative stress and inflammatory responses through reactive oxygen species (ROS) levels, antioxidant status, [Ca 2+ ]i, nuclear migration of two redox-sensitive transcription factors, NF-κB p65 and Nrf-2, expression of MAP kinase (p-Erk, p-p38), NF-κB p65, COX-2 and Nrf-2. Cellular changes in ΔΨm, acidic vesicular organelle formation, cell cycle analysis and scanning electron microscopy analysis were performed. KEY RESULTSEPA offered significant cytoprotection by increasing EPA/AA ratios in cell membranes, inhibiting ROS generation, enhancing antioxidant status and modulating nuclear translocation of redox-sensitive transcription factors (NF-κB p65 and Nrf-2) and expression of NF-κB p65, COX-2 and Nrf-2. Furthermore, TCDD-induced upstream events of MAPK phosphorylation, the increase in [Ca 2+ ]i levels and cell surface changes in microvilli were significantly inhibited by EPA. EPA treatment maintained ΔΨm and prevented formation of acidic vesicular organelles. CONCLUSION AND IMPLICATIONSThe present study demonstrates for the first time some underlying molecular mechanisms of cytoprotection exerted by EPA against TCDD-induced oxidative stress and inflammatory responses. AbbreviationsAA, arachidonic acid; AEBSF, 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride; AhR, aryl hydrocarbon receptor; AVO, acidic vesicular organelles; CCCP, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone; DAB, diaminobenzidine; DCF-DA, 2′,7′-dichlorodihydrofluoresceindiacetate; DiOC6, 3,3′-dihexyloxacarbocyanine iodide; EPA, eicosapentaenoic acid; FITC, fluorescein isothiocyanate; Fura-2 AM, Fura-2-acetoxymethyl ester; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NQO1, NAD(P)H dehydrogenase quinone1; Nrf-2, nuclear factor erythroid 2-related factor 2; OPT, ortho-phthalaldehyde; ROS, reactive oxygen species; TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin