Modulation of Nrf2/Keap1 pathway by dietary phytochemicals

Ahmed E. Atia, Azman bin Abdullah


Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), also known as NFE2L2, has emerged as a transcription factor that plays a crucial role in cellular protection against free radical damage and reduce the incidence of the radical derived degenerative diseases such as cancer. Nrf2 is a basic leucine zipper transcription factor that binds to ARE leading to induction of a verity of ARE driven detoxification and antioxidant genes. In basal conditions, Nrf2 is sequestered in the cytoplasm by an inhibitory partner the cytoskeletal anchoring protein Kelch-like ECH associated protein-1 (Keap1) through extensive hydrogen bonds. Inducers dissociate this complex, allowing Nrf2 to translocate to the nucleus. A number of studies have elucidated that nutritional compounds can modulate the activation of Nrf2/Keap1 system. This review aims to discuss some of the key nutritional compounds that enhance the activation of Nrf2, with consequent antioxidant and anti-inflammatory defensive effects.


Nrf2, Keap1, Phytochemicals

Full Text:



Surh Y. J. Cancer chemoprevention with dietary phytochemicals. Nat Rev Cancer. 2003;3:768-80.

Finley J. W., Kong A. N., Hintze, K. J. et al. Antioxidants in foods: state of the science important to the food industry. J Agric Food Chem. 2011;59:6837-46.

Li Y, Paonessa JD, Zhang Y. Mechanism of Chemical Activation of Nrf2. P Los One. 2012;7(4):e35122.

Wattenberg L. W. Chemoprophylaxis of carcinogenesis: a review. Cancer Res. 1966;26:1520-6.

Itoh K, Wakabayashi N, Katoh Y, Ishii T, Igarashi K, Engel J. D., Yamamoto M. Keap1 represses nuclear activation of antioxidant responsive elements by Nrf2 through binding to the amino-terminal Neh2 domain. Genes & development. 1999;13(1):76-86.

Motohashi H, O’Connor T, Katsuoka F, Engel J. D., Yamamoto M. Integration and diversity of the regulatory network composed of Maf and CNC families of transcription factors. Gene. 2002;294:1-12.

Bae S. H., Sung S. H., Oh S. Y., Lim J. M., Lee S. K., Park Y. N. et al. Sestrins activate Nrf2 by promoting p62-dependent autophagic degradation of Keap1 and prevent oxidative liver damage. Cell Metab. 2013;17:73-84.

Malloy M. T., McIntosh D. J., Walters T. S., Flores A, Goodwin J. S., Arinze I. J. Trafficking of the transcription factor Nrf2 to promyelocytic leukemia-nuclear bodies: implications for degradation of Nrf2 in the nucleus. J Biol Chem. 2013;288(20):14569-83.

Kilic U, Kilic E, Tuzcu Z, Tuzcu M, Ozercan I. H., Yilmaz O et al. Melatonin suppresses cisplatin-induced nephrotoxicity via activation of Nrf-2/HO-1 pathway. Nutr Metab. 2013;10:7.

Zhang J, Hosoya T, Maruyama A, Nishikawa K, Maher JM, Ohta T et al. Nrf2 Neh5 domain is differentially utilized in the transactivation of cytoprotective genes. Biochem J. 2007;404:459-66.

Baird L, Dinkova-Kostova A. T. The cytoprotective role of the Keap1-Nrf2 pathway. Archives of Toxicol. 2011;85:241-72.

McMahon M, Thomas N, Itoh K, Yamamoto M, Hayes J. D. Redox-regulated turnover of Nrf2 is determined by at least two separate protein domains, the redox-sensitive Neh2 degron and the redox-insensitive Neh6 degron. J Biol Chem. 2004;279:31556-67.

Nioi P, Nguyen T, Sherratt P. J., Pickett C. B. The carboxy-terminal Neh3 domain of Nrf2 is required for transcriptional activation. Mol Cell Biol 2005;25:10895-906.

Katoh Y, Itoh K, Yoshida E, Miyagishi M, Fukamizu A, Yamamoto M. Two domains of Nrf2 cooperatively bind CBP, a CREB binding protein, and synergistically activate transcription. Genes Cells. 2001;6:857-68.

Tong K. I., Padmanabhan B, Kobayashi A, Shang C, Hirotsu Y, Yokoyama S, Yamamoto M. Different electrostatic potentials define ETGE and DLG motifs as hinge and latch in oxidative stress response. Mol Cell Biol. 2007;27:7511-21.

Tong K. I., Katoh Y, Kusunoki H, Itoh K, Tanaka T, Yamamoto M. Keap1 recruits Neh2 through binding to ETGE and DLG motifs: characterization of the two-site molecular recognition model. Mol Cell Biol. 2006;26:2887-2900.

Zhang M, An C, Gao Y, Leak RK, Chen J, Zhang F. Emerging roles of Nrf2 and phase II antioxidant enzymes in neuroprotection. Prog Neurobiol. 2013;100:30-47.

Xiaoqing He and Qiang Ma. Nrf2 cysteine residues are critical for oxidant/electrophile- sensing, kelch-like ECH-associated protein-1-dependent ubiquitination-proteasomal degradation, and transcription activation. Mol Pharmacol. 2009;76:1265-78.

Dinkova-Kostova AT, Holtzclaw WD, Kensler TW. The role of Keap1 in cellular protective responses. Chem Res Toxicol. 2005;18:1779-91.

Prestera T, Zhang Y, Spencer SR et al. The electrophile counterattack response: protection against neoplasia and toxicity. Adv Enzyme Regul. 1993;33:281-96.

Nguyen T, Sherratt P. J., Pickett C. B. Regulatory mechanisms controlling gene expression mediated by the antioxidant response element. Annu Rev Pharmacol Toxicol. 2003;43:233-60.

Surh Y. J., Kundu J. K., Na H. K. Nrf2 as a master redox switch in turning on the cellular signaling involved in the induction of cytoprotective genes by some chemopreventive phytochemicals. Planta Med. 2008;74:1526-39.

Rong Yu, Tse-Hua Tan, and A. N. Tony Kong. Butylated hydroxyanisole and its metabolite tert-butylhydroquinone differentially regulate mitogen-activated protein kinases. J Biol Chem. 1997;272(46):28962-70.

Rong yu, Sandhya Mandlekar, A. N. Tony Kong. Molecular Mechanisms of Butylated Hydroxylanisole-Induced Toxicity: Induction of Apoptosis through Direct Release of Cytochrome C. MOL. 2000;58:431-7.

McCormick, D. L. et al. Inhibition of 7,12-dimethylbenz(a)anthracene- induced rat mammary carcinogenesis by concomitant or postcarcinogen antioxidant exposure. Cancer Res. 1984;44:2858-63.

Kahl R. Synthetic antioxidants: biochemical action and interference with radiation, toxic compounds, chemical mutagens and chemical carcinogens. Toxicol. 1984;59:179-94.

Benson AM, Hunkeler MJ, Talalay P. Increase of NAD(P)H: quinine reductase by dietary antioxidants: possible role in protection against carcinogenesis and toxicity. Proc Natl Acad Sci USA. 1980;77:5216-20.

Cummings SW, Prough RA. Butylated hydroxyanisole-stimulated NADPH-oxidase activity in rat microsomal fractions. J Biol Chem. 1983;258:12315-9.

Ito N, Fukushima S, Hagiwara A, Shibata M, Ogiso T. Carcinogenicity of butylated hydroxyanisole in F344 rats. J Natl Cancer Inst. 1983;70:343-52.

Clayson DB, Iverson F, Nera EA, Lok E. Early indicators of potential neoplasia produced in the rat forestomach by non-genotoxic agents: the importance of induced cellular proliferation. Mutat Res. 1991;248(2):321-31.

Venugopal, R., Jaiswal, A. K. Nrf1 and Nrf2 positively and c-Fos and Fra1 negatively regulate the human antioxidant response element-mediated expression of NAD(P)H: quinone oxidoreductase1 gene. Proc Natl Acad Sci USA. 1996;93:14960-5.

Wattenberg L. W., Coccia J. B., Lam L. K. Inhibitory effects of phenolic compounds on benzo(a)pyrene- induced neoplasia. Cancer Res. 1980;40:2820-3.

Sharma R, Sharma A, Chaudhary P, Pearce V, Vatsyayan R, Singh S.V. et al. Role of lipid peroxidation in cellular responses to D,L-sulforaphane, a promising cancer chemopreventive agent. Biochem. 2010;49:3191-3202.

Dandan Han, Kyung Ho Row. Separation and Purification of Sulforaphane from Broccoli by Solid Phase Extraction. Mol Sci. 2011;1422–0067.

Brooks JD, Paton VG, Vidanes G. Potent induction of phase 2 enzymes in human prostate cells by sulforaphane. Cancer Epidemiol Biomarkers Prev. 2001;10:949-54.

Chen YR, Wang W, Kong AN, Tan TH. Molecular mechanisms of c-Jun N-terminal kinase-mediated apoptosis induced by anticarcinogenic isothiocyanates. J Biol Chem. 1998;273:1769-75.

Thimmulappa R. K., Mai K. H., Srisuma S, Kensler T, Yamamoto M, Biswal S. Identification of Nrf2-regulated genes induced by the chemopreventive agent sulforaphane by oligonucleotide microarray. Cancer Res. 2002;62(18):5196-5203.

Kivela A. M., Makinen P. I., Jyrkkanen H. K., Mella-Aho E, Xia Y, Kansanen E et al. Sulforaphane inhibits endothelial lipase expression through NF kappa B in endothelial cells. Atherosclerosis. 2010;213(1):122-8.

Zhang C, Su Z. Y., Khor T. O., Shu L, Kong A. N. Sulforaphane enhances Nrf2 expression in prostate cancer TRAMP C1 cells through epigenetic regulation. Biochm. Pharmacol. 2013;85(9):1398-1404.

Hong F, Freeman M. L., Liebler D. C. Identification of sensor cysteines in human Keap1 modified by the cancer chemopreventive agent sulforaphane, Chemical Research in Toxicology 2005;18:1917-26.

Hu C, Eggler A. L., Mesecar A. D., van Breemen R. B. Modification of Keap1 cysteine residues by sulforaphane. Chem Res Toxicol. 2011;24:515-21.

Keum Y. S. Regulation of the Keap1/Nrf2 system by chemopreventive sulforaphane: implications of posttranslational modifications. Annals New York Academy Sci. 2011;1229:184-9.

Xiao D, Singh SV. Phenethyl isothiocyanate-induced apoptosis in p53-deficient PC-3 human prostate cancer cell line is mediated by extracellular signal-regulated kinases. Cancer Res. 2002;62:3615-9.

Fimognari C, Nusse M, Cesari R, Iori R, Cantelli-Forti G, Hrelia P. Growth inhibition, cell-cycle arrest and apoptosis in human T-cell leukemia by the isothiocyanate sulforaphane. Carcinogenesis. 2002;23:581-6.

Zhang Y, Munday R. Dithiolethiones for cancer chemoprevention: where do we stand? Mol Cancer Ther. 2008;7:3470-9.

Tran QT, Xu L, Phan V, Goodwin SB, Rahman M, Jin VX et al. Chemical genomics of cancer chemopreventive dithiolethiones. Carcinogenesis. 2009;30(3):480-6.

Bhattacharyya S, Zhou H, Seiner DR, Gates KS. Inactivation of protein tyrosine phosphatases by oltipraz and other cancer chemopreventive 1,2-dithiole-3-thiones. Bioorg Med Chem. 2010;18:5945-9.

Kensler T. W., Groopman J. D., Sutter T. R., Curphey T. J., Roebuck B. D. Development of cancer chemopreventive agents: oltipraz as a paradigm. Chem Res Toxicol. 1999;12:113-26.

Leiro J, Alvarez E, Arranz J. A., Laguna R, Uriarte E, Orallo F. Effects of cis-resveratrol on inflammatory murine macrophages: antioxidant activity and down-regulation of inflammatory genes. J Leukoc Biol. 2004;75:1156-65.

Lopez-Velez M, Martinez-Martinez F, Del Valle-Ribes C. The study of phenolic compounds as natural antioxidants in wine. Crit Rev Food Sci Nutr. 2003;43:233-44.

Rubiolo J. A., Mithieux G, Vega F. V. Resveratrol protects primary rat hepatocytes against oxidative stress damage: activation of the Nrf2 transcription factor and augmented activities of antioxidant enzymes. Eur J Pharmacol. 2008;591:66-72.

Palsamy P, Subramanian S. Resveratrol protects diabetic kidney by attenuating hyperglycemia-mediated oxidative stress and renal inflammatory cytokines via Nrf2eKeap1 signalling, Biochem Biophys Acta. 2011;1812:719-31.

Seve M, Chimienti F, Devergnas S et al. Resveratrol enhances UVA-induced DNA damage in HaCaT human keratinocytes. Med Chem. 2005;1:629-33.

Bishayee A. Cancer prevention and treatment with resveratrol: from rodent studies to clinical trials. Cancer Prev Res. 2009;2:409-18.

Jang M, Cai L, Udeani GO et al. Cancer chemopreventive activity of resveratrol, a natural product derived from grapes. Sci. 1997;275:218-20.

Banerjee S, Bueso Ramos C, Aggarwal BB. Suppression of 7,12-dimethylbenz(a)anthracene-induced mammary carcinogenesis in rats by resveratrol: role of nuclear factor-κB, cycloxygenase 2, and matrix metalloprotease 9. Cancer Res. 2002;62:4945-54.

Harper CE, patel BB, Wang J et al. Resveratrol suppresses prostate cancer progression in transgenic mice. Carcinogenesis. 2007;28:1946-53.

Zhou HB, Chen JJ, Wang WX, Cai JT, Du Q. Anticancer activity of resveratrol on implanted human primary gastric carcinoma cells in nude mice. World J Gastroenterol. 2005;11:280-4.

Sengottuvelan M, Viswanathan P, Nalini N. Chemopreventive effect of trans-resveratrol - a phytoalexin against colonic aberrant crypt foci and cell proliferation in 1,2-dimethylhydrazine induced colon carcinogenesis. Carcinogenesis. 2006;27:1038-46.

Bishayee A, Dhir N. Resveratrol-mediated chemoprevention of diethylnitrosamine-initiated hepatocarcinogenesis: inhibition of cell proliferation and induction of apoptosis. Chem Biol Interact. 2009;179:131-44.

Athar M, Back JH, Kopelovich L, Bickers DR, Kim Al. Multiple molecular targets of resveratrol: anti-carcinogenic mechanisms. Arch Biochem Biophys. 2009;486:95-102.

Stakleff KS, Sloan T, Blanco D, Marcanthony S, Booth TD, Bishayee A. Resveratrol exerts differential effects in vitro and in vivo against ovarian cancer cells. Asian Pacific J Cancer Prev. 2012;13(4):1333-40.

Tapia E, Soto V, Ortiz-Vega KM, Zarco-Márquez G, Molina-Jijón E, Cristóbal-García M et al. Curcumin induces Nrf2 nuclear translocation and prevents glomerular hypertension, hyperfiltration, oxidant stress, and the decrease in antioxidant enzymes in 5/6 nephrectomised rats. Oxid Med Cell Longev. 2012;2012:269039.

Singh S, Khar A. Biological effects of curcumin and its role in cancer chemoprevention and therapy. Anticancer Agents Med Chem. 2006;6(3):259-70.

Sreejayan M. N. Nitric oxide scavenging by curcuminoids. J Pharm Pharmacol. 1997;49(1):105-7.

Balogun E., Hoque M., Gong P. et al. Curcumin activates the haem oxygenase-1 gene via regulation of Nrf2 and the antioxidant-responsive element. Biochem J. 2003;371(3):887-95.

Garg R, Gupta S, Maru G.B. Dietary curcumin modulates transcriptional regulators of phase I and phase II enzymes in benzoa. pyrene-treated mice: mechanism of its anti-initiating action. Carcinogenesis. 2008;29:1022-32.

Iqbal M, Sharma S.D, Okazaki Y, Fujisawa M, Okada S. Dietary supplementation of curcumin enhances antioxidant and phase II metabolizing enzymes in ddY male mice: possible role in protection against chemical carcinogenesis and toxicity. Pharmacol Toxicol. 2003;A92:33-8.

Nesaretnam K, Guthrie N, Chambers AF, Carroll KK. Effects of tocotrienols on the growth of a human breast cancer cell line in culture. Lipids. 1995;30:1139-43.

Sylvester PW, Theriault A. Role of tocotrienols in the prevention of cardiovascular disease and breast cancer. Curr Top Nutraceutical Res. 2003;1:121-36.

Brigelius-Flohe R, Traber M. G. Vitamin E: function and metabolism. Federation of American Societies Experiment Biol J. 1999;13:1145-55.

Pruthi S, Allison TG, Hensrud DD. Vitamin E supplementation in the prevention of coronary heart disease. Mayo Clinic Proceedings. 2001;76(11):1131-6.

Inokuchi H, Hirokane H, Tsuzuki T, Nakagawa K, Igarashi M, Miyazawa T. Anti-angiogenic activity of tocotrienol. Biosci Biotechnol Biochem. 2003;67(7):1623-7.

Barve A, Khor T. O., Nair S, Reuhl K, Suh N, Reddy B. Newmark H., Kong A. N. Gamma-tocopherol-enriched mixed tocopherol diet inhibits prostate carcinogenesis in TRAMP mice. Int J Cancer. 2009;124:1693-9.

Hsieh TC, Elangovan S, Wu JM. Differential suppression of proliferation in MCF-7 and MDA-MB-231 breast cancer cells exposed to alpha-, gamma- and delta-tocotrienols is accompanied by altered expression of oxidative stress modulatory enzymes. Anticancer Res. 2010;30:4169-76.

Iqbal J, Minhajuddin M, Beg ZH. Suppression of 7,12-dimethylbenz[alpha]anthracene induced carcinogenesis and hypercholesterolaemia in rats by tocotrienol- rich fraction isolated from rice bran oil. Eur J Cancer Prev. 2003;B12:447-53.

Ngah WZ, Jarien Z, San MM, Marzuki A, Top GM, Shamaan NA et al. Effect of tocotrienols on hepatocarcinogenesis induced by 2-acetylaminofluorene in rats. Am J Clin Nutr. 1991;53:1076S-81S.

Li G, Lee M. J., Liu A. B., Yang Z, Lin Y, Shih W. J., Yang C. S. The antioxidant and anti-inflammatory activities of tocopherols are independent of Nrf2 in mice. Free Radical Biol Med. 2012;52:1151-8.