Effects of Curcumin on Alveolar Bone Loss in Experimental Periodontitis in Rats: A Morphometric and Histopathologic Study
Abstract
Abstract.Background: Curcumin is found in the rhizomes of the turmeric plant that has been showed antioxidant and anti-inflammatory effect. The aim of this study was to evaluate the effects of systemic curcumin therapy on alveolar bone loss in an experimental periodontitis model in rats. Material and Methods: Thirty-two male Wistar rats were randomly divided to 4 groups: 75 mg/kg/daily curcumin (C75; n =8), 150 mg/kg/daily curcumin (C150; n =8), Control (n =8), and Ligated (n =8). Curcumin was administrated using gastric gavage. After 12 days, the rats were sacrificed. Right mandibles samples were histopathologically examined. Alveolar bone loss was measured. Interleukin 1β (IL-1β) and interleukin 10 (IL-10) were evaluated in the serum samples and gingival homogenates. Results: The measurements of alveolar bone loss in the mandibular molars revealed significantly higher bone-loss values in the Ligated group than the Control, C75 and C150 groups. The IL-1β levels in the gingival homogenates were significantly increased in the Ligated group compared to those of the Control, C75 and C150 groups. The serum IL-1β levels in the Ligated group were significantly higher than the Control group. The mean osteoblast numbers in the Ligated group were lower than those of the Control, C75 and C150 groups. The C150 groups showed significantly more osteoblasts than the Control group. The osteoclast numbers in the Ligated group increased significantly compared to the C75, C150 and control groups. Conclusion: This study demonstrates that systemic administration of curcumin at the 75 and 150mg/kg doses reduced alveolar bone loss in the periodontal disease in rats.
Keywords: Alveolar bone loss, Antioxidant, Curcumin, Ligature-induced, Histomorphometric, Micronutrition
Literature
Hasturk, H., A. Kantarci, and T.E. Van Dyke (2012). Paradigm shift in the pharmacological management of periodontal diseases. Front Oral Biol, 15.p. 160 – 76.
Kinane, D.F. (2001). Causation and pathogenesis of periodontal disease. Periodontol 2000, 25.p. 8 – 20.
George, J.P., Shobha, R., Lazarus, F.J. (2013). Folic acid: A positive influence on periodontal tissues during health and disease. International Journal of Health & Allied Sciences, 2.3: p. 145 – 152.
Toker, H., H. Ozdemir, K. Eren, H. Ozer, and G. Sahin (2009). N-acetylcysteine, a thiol antioxidant, decreases alveolar bone loss in experimental periodontitis in rats. J Periodontol, 80.4: p. 672 – 8.
Tomofuji, T., D. Ekuni, K. Irie, T. Azuma, Y. Endo, N. Tamaki, T. Sanbe, J. Murakami, T. Yamamoto, and M. Morita (2009). Preventive effects of a cocoa-enriched diet on gingival oxidative stress in experimental periodontitis. J Periodontol, 80.11: p. 1799 – 808.
Toker, H., F. Ozan, H. Ozer, H. Ozdemir, K. Eren, and H. Yeler (2008). A morphometric and histopathologic evaluation of the effects of propolis on alveolar bone loss in experimental periodontitis in rats. J Periodontol, 79.6: p. 1089 – 94.
Chapple, I.L. and J.B. Matthews (2007). The role of reactive oxygen and antioxidant species in periodontal tissue destruction. Periodontol 2000, 43.p. 160 – 232.
Halliwell, B. (1991). Reactive oxygen species in living systems: source, biochemistry, and role in human disease. Am J Med, 91.3C: p. 14S-22S.
Wilken, R., M.S. Veena, M.B. Wang, and E.S. Srivatsan (2011). Curcumin: A review of anti-cancer properties and therapeutic activity in head and neck squamous cell carcinoma. Mol Cancer, 10.p. 12.
Manifar, S., Obwaller, A., Gharehgozloo, A., Kordi, H.R., Akhondzadeh, S. (2012). Curcumin gel in the treatment of minor aphthous ulcer: A randomized, placebo- controlled trial. J Med Plants, 11.p. 40 – 5.
Gottumukkala, S.N., S. Koneru, S. Mannem, and N. Mandalapu (2013). Effectiveness of sub gingival irrigation of an indigenous 1% curcumin solution on clinical and microbiological parameters in chronic periodontitis patients: A pilot randomized clinical trial. Contemp Clin Dent, 4.2: p. 186 – 91.
Liao, S., J. Xia, Z. Chen, S. Zhang, A. Ahmad, L. Miele, F.H. Sarkar, and Z. Wang (2011). Inhibitory effect of curcumin on oral carcinoma CAL-27 cells via suppression of Notch-1 and NF-kappaB signaling pathways. J Cell Biochem, 112.4: p. 1055 – 65.
Dickinson, D.A., K.E. Iles, H. Zhang, V. Blank, and H.J. Forman (2003). Curcumin alters EpRE and AP-1 binding complexes and elevates glutamate-cysteine ligase gene expression. FASEB J, 17.3: p. 473 – 5.
Lin, S.S., K.C. Lai, S.C. Hsu, J.S. Yang, C.L. Kuo, J.P. Lin, Y.S. Ma, C.C. Wu, and J.G. Chung (2009). Curcumin inhibits the migration and invasion of human A549 lung cancer cells through the inhibition of matrix metalloproteinase-2 and -9 and Vascular Endothelial Growth Factor (VEGF). Cancer Lett, 285.2: p. 127 – 33.
Strimpakos, A.S. and R.A. Sharma (2008). Curcumin: preventive and therapeutic properties in laboratory studies and clinical trials. Antioxid Redox Signal, 10.3: p. 511 – 45.
Kunnumakkara, A.B., S. Guha, S. Krishnan, P. Diagaradjane, J. Gelovani, and B.B. Aggarwal (2007). Curcumin potentiates antitumor activity of gemcitabine in an orthotopic model of pancreatic cancer through suppression of proliferation, angiogenesis, and inhibition of nuclear factor-kappaB-regulated gene products. Cancer Res, 67.8: p. 3853 – 61.
Camacho-Barquero, L., I. Villegas, J.M. Sanchez-Calvo, E. Talero, S. Sanchez-Fidalgo, V. Motilva, and C. Alarcon de la Lastra (2007). Curcumin, a Curcuma longa constituent, acts on MAPK p38 pathway modulating COX-2 and iNOS expression in chronic experimental colitis. Int Immunopharmacol, 7.3: p. 333 – 42.
Mun, S.H., H.S. Kim, J.W. Kim, N.Y. Ko, K. Kim do, B.Y. Lee, B. Kim, H.S. Won, H.S. Shin, J.W. Han, H.Y. Lee, Y.M. Kim, and W.S. Choi (2009). Oral administration of curcumin suppresses production of matrix metalloproteinase (MMP)-1 and MMP-3 to ameliorate collagen-induced arthritis: inhibition of the PKCdelta/JNK/c-Jun pathway. J Pharmacol Sci, 111.1: p. 13 – 21.
Swarnakar, S. and S. Paul (2009). Curcumin arrests endometriosis by downregulation of matrix metalloproteinase-9 activity. Indian J Biochem Biophys, 46.1: p. 59 – 65.
Chen, D., M. Nie, M.W. Fan, and Z. Bian (2008). Anti-inflammatory activity of curcumin in macrophages stimulated by lipopolysaccharides from Porphyromonas gingivalis. Pharmacology, 82.4: p. 264 – 9.
Srimal, R.C. and B.N. Dhawan (1973). Pharmacology of diferuloyl methane (curcumin), a non-steroidal anti-inflammatory agent. J Pharm Pharmacol, 25.6: p. 447 – 52.
Verma, S.P., B.R. Goldin, and P.S. Lin (1998). The inhibition of the estrogenic effects of pesticides and environmental chemicals by curcumin and isoflavonoids. Environ Health Perspect, 106.12: p. 807 – 12.
Kim, G.Y., K.H. Kim, S.H. Lee, M.S. Yoon, H.J. Lee, D.O. Moon, C.M. Lee, S.C. Ahn, Y.C. Park, and Y.M. Park (2005). Curcumin inhibits immunostimulatory function of dendritic cells: MAPKs and translocation of NF-kappa B as potential targets. J Immunol, 174.12: p. 8116 – 24.
Binion, D.G., J. Heidemann, M.S. Li, V.M. Nelson, M.F. Otterson, and P. Rafiee (2009). Vascular cell adhesion molecule-1 expression in human intestinal microvascular endothelial cells is regulated by PI 3-kinase/Akt/MAPK/NF-kappaB: inhibitory role of curcumin. Am J Physiol Gastrointest Liver Physiol, 297.2: p. G259 – 68.
Kumar, A., S. Dhawan, N.J. Hardegen, and B.B. Aggarwal (1998). Curcumin (Diferuloylmethane) inhibition of tumor necrosis factor (TNF)-mediated adhesion of monocytes to endothelial cells by suppression of cell surface expression of adhesion molecules and of nuclear factor-kappaB activation. Biochem Pharmacol, 55.6: p. 775 – 83.
Cekici, A., A. Kantarci, H. Hasturk, and T.E. Van Dyke (2014). Inflammatory and immune pathways in the pathogenesis of periodontal disease. Periodontol 2000, 64.1: p. 57 – 80.
Reyes-Gordillo, K., J. Segovia, M. Shibayama, P. Vergara, M.G. Moreno, and P. Muriel (2007). Curcumin protects against acute liver damage in the rat by inhibiting NF- kappaB, proinflammatory cytokines production and oxidative stress. Biochim Biophys Acta, 1770.6: p. 989 – 96.
Fu, Y., S. Zheng, J. Lin, J. Ryerse, and A. Chen (2008). Curcumin protects the rat liver from CCl4-caused injury and fibrogenesis by attenuating oxidative stress and suppressing inflammation. Mol Pharmacol, 73.2: p. 399 – 409.
Yu, J.J., L.B. Pei, Y. Zhang, Z.Y. Wen, and J.L. Yang (2015). Chronic Supplementation of Curcumin Enhances the Efficacy of Antidepressants in Major Depressive Disorder: A Randomized, Double-Blind, Placebo-Controlled Pilot Study. J Clin Psychopharmacol, 35.4: p. 406 – 10.
Evans, K.E. and S.W. Fox (2007). Interleukin-10 inhibits osteoclastogenesis by reducing NFATc1 expression and preventing its translocation to the nucleus. BMC Cell Biol, 8.p. 4.
Zhang, Q., B. Chen, F. Yan, J. Guo, X. Zhu, S. Ma, and W. Yang (2014). Interleukin-10 inhibits bone resorption: a potential therapeutic strategy in periodontitis and other bone loss diseases. Biomed Res Int, 2014.p. 284836.
Sun, J., Y. Zhao, and J. Hu (2013). Curcumin inhibits imiquimod-induced psoriasis-like inflammation by inhibiting IL-1beta and IL-6 production in mice. PLoS One, 8.6: p. e67078.
Wu, S.J., K.W. Tam, Y.H. Tsai, C.C. Chang, and J.C. Chao (2010). Curcumin and saikosaponin a inhibit chemical-induced liver inflammation and fibrosis in rats. Am J Chin Med, 38.1: p. 99 – 111.
Ma, C., Z. Ma, Q. Fu, and S. Ma (2013). Curcumin attenuates allergic airway inflammation by regulation of CD4+CD25+ regulatory T cells (Tregs)/Th17 balance in ovalbumin-sensitized mice. Fitoterapia, 87.p. 57 – 64.
Epstein, J., G. Docena, T.T. MacDonald, and I.R. Sanderson (2010). Curcumin suppresses p38 mitogen-activated protein kinase activation, reduces IL-1beta and matrix metalloproteinase-3 and enhances IL-10 in the mucosa of children and adults with inflammatory bowel disease. Br J Nutr, 103.6: p. 824 – 32.
McCann, M.J., S. Johnston, K. Reilly, X. Men, E.J. Burgess, N.B. Perry, and N.C. Roy (2014). The effect of turmeric (Curcuma longa) extract on the functionality of the solute carrier protein 22 A4 (SLC22A4) and interleukin-10 (IL-10) variants associated with inflammatory bowel disease. Nutrients, 6.10: p. 4178 – 90.
Zhong, K. (2015). Curcumin Mediates a Protective Effect Via TLR-4/NF-kappaB Signaling Pathway in Rat Model of Severe Acute Pancreatitis. Cell Biochem Biophys.
Sciberras, J.N., S.D. Galloway, A. Fenech, G. Grech, C. Farrugia, D. Duca, and J. Mifsud (2015). The effect of turmeric (Curcumin) supplementation on cytokine and inflammatory marker responses following 2 hours of endurance cycling. J Int Soc Sports Nutr, 12.1: p. 5.
Aggarwal, B.B., S. Banerjee, U. Bharadwaj, B. Sung, S. Shishodia, and G. Sethi (2007). Curcumin induces the degradation of cyclin E expression through ubiquitin- dependent pathway and up-regulates cyclin-dependent kinase inhibitors p21 and p27 in multiple human tumor cell lines. Biochem Pharmacol, 73.7: p. 1024 – 32.
Folwarczna, J., M. Zych, and H.I. Trzeciak (2010). Effects of curcumin on the skeletal system in rats. Pharmacol Rep, 62.5: p. 900 – 9.
Yanagisawa, D., H. Taguchi, A. Yamamoto, N. Shirai, K. Hirao, and I. Tooyama (2011). Curcuminoid binds to amyloid-beta1 – 42 oligomer and fibril. J Alzheimers Dis, 24 Suppl 2.p. 33 – 42.
Sanmukhani, J., V. Satodia, J. Trivedi, T. Patel, D. Tiwari, B. Panchal, A. Goel, and C.B. Tripathi (2014). Efficacy and safety of curcumin in major depressive disorder: a randomized controlled trial. Phytother Res, 28.4: p. 579 – 85.
Jiao, Y., J.t. Wilkinson, X. Di, W. Wang, H. Hatcher, N.D. Kock, R. D›Agostino, Jr., M.A. Knovich, F.M. Torti, and S.V. Torti (2009). Curcumin, a cancer chemopreventive and chemotherapeutic agent, is a biologically active iron chelator. Blood, 113.2: p. 462 – 9.
Aggarwal, S., Y. Takada, S. Singh, J.N. Myers, and B.B. Aggarwal (2004). Inhibition of growth and survival of human head and neck squamous cell carcinoma cells by curcumin via modulation of nuclear factor-kappaB signaling. Int J Cancer, 111.5: p. 679 – 92.
Abe, Y., S. Hashimoto, and T. Horie (1999). Curcumin inhibition of inflammatory cytokine production by human peripheral blood monocytes and alveolar macrophages. Pharmacol Res, 39.1: p. 41 – 7.
Safieh-Garabedian, B., S. Poole, A. Allchorne, J. Winter, and C.J. Woolf (1995). Contribution of interleukin-1 beta to the inflammation-induced increase in nerve growth factor levels and inflammatory hyperalgesia. Br J Pharmacol, 115.7: p. 1265 – 75.
Toker, H., H. Ozdemir, H. Balci, and H. Ozer (2012). N-acetylcysteine decreases alveolar bone loss on experimental periodontitis in streptozotocin-induced diabetic rats. J Periodontal Res, 47.6: p. 793 – 9.
Miley, D.D., M.N. Garcia, C.F. Hildebolt, W.D. Shannon, R.A. Couture, C.L. Anderson Spearie, D.A. Dixon, E.M. Langenwalter, C. Mueller, and R. Civitelli (2009). Cross- sectional study of vitamin D and calcium supplementation effects on chronic periodontitis. J Periodontol, 80.9: p. 1433 – 9.
Munoz, C.A., R.D. Kiger, J.A. Stephens, J. Kim, and A.C. Wilson (2001). Effects of a nutritional supplement on periodontal status. Compend Contin Educ Dent, 22.5: p. 425 – 8, 430, 432 passim; quiz 440.
Neiva, R.F., K. Al-Shammari, F.H. Nociti, Jr., S. Soehren, and H.L. Wang (2005). Effects of vitamin-B complex supplementation on periodontal wound healing. J Periodontol, 76.7: p. 1084 – 91.
Kaye, E.K. (2012). Nutrition, dietary guidelines and optimal periodontal health. Periodontol 2000, 58.1: p. 93 – 111.
Nabavi, S.F., Daglia, M., Moghaddam, A. H., Habtemariam, S., Nabavi, S.M. (2014). Curcumin and liver disease: from chemistry to medicine. Comprehensive Reviews in Food Science and Food Safety, 13.1: p. 62 – 77.
Anand, P., S.G. Thomas, A.B. Kunnumakkara, C. Sundaram, K.B. Harikumar, B. Sung, S.T. Tharakan, K. Misra, I.K. Priyadarsini, K.N. Rajasekharan, and B.B. Aggarwal (2008). Biological activities of curcumin and its analogues (Congeners) made by man and Mother Nature. Biochem Pharmacol, 76.11: p. 1590 – 611.
Somparn, P., C. Phisalaphong, S. Nakornchai, S. Unchern, and N.P. Morales (2007). Comparative antioxidant activities of curcumin and its demethoxy and hydrogenated derivatives. Biol Pharm Bull, 30.1: p. 74 – 8.
Shishodia, S., H.M. Amin, R. Lai, and B.B. Aggarwal (2005). Curcumin (diferuloylmethane) inhibits constitutive NF-kappaB activation, induces G1/S arrest, suppresses proliferation, and induces apoptosis in mantle cell lymphoma. Biochem Pharmacol, 70.5: p. 700 – 13.
Anand, P., B. Sung, A.B. Kunnumakkara, K.N. Rajasekharan, and B.B. Aggarwal (2011). Suppression of pro-inflammatory and proliferative pathways by diferuloylmethane (curcumin) and its analogues dibenzoylmethane, dibenzoylpropane, and dibenzylideneacetone: role of Michael acceptors and Michael donors. Biochem Pharmacol, 82.12: p. 1901 – 9.
Zhou, T., D. Chen, Q. Li, X. Sun, Y. Song, and C. Wang (2013). Curcumin inhibits inflammatory response and bone loss during experimental periodontitis in rats. Acta Odontol Scand, 71.2: p. 349 – 56.
Elburki, M.S., C. Rossa, M.R. Guimaraes, M. Goodenough, H.M. Lee, F.A. Curylofo, Y. Zhang, F. Johnson, and L.M. Golub (2014). A novel chemically modified curcumin reduces severity of experimental periodontal disease in rats: initial observations. Mediators Inflamm, 2014.p. 959471.
Moon, H.J., W.K. Ko, S.W. Han, D.S. Kim, Y.S. Hwang, H.K. Park, and I.K. Kwon (2012). Antioxidants, like coenzyme Q10, selenite, and curcumin, inhibited osteoclast differentiation by suppressing reactive oxygen species generation. Biochem Biophys Res Commun, 418.2: p. 247 – 53.
Kim, H.J., E.J. Chang, H.M. Kim, S.B. Lee, H.D. Kim, G. Su Kim, and H.H. Kim (2006). Antioxidant alpha-lipoic acid inhibits osteoclast differentiation by reducing nuclear factor-kappaB DNA binding and prevents in vivo bone resorption induced by receptor activator of nuclear factor-kappaB ligand and tumor necrosis factor-alpha. Free Radic Biol Med, 40.9: p. 1483 – 93.
Srinivasan, S., A. Koenigstein, J. Joseph, L. Sun, B. Kalyanaraman, M. Zaidi, and N.G. Avadhani (2010). Role of mitochondrial reactive oxygen species in osteoclast differentiation. Ann N Y Acad Sci, 1192.p. 245 – 52.
von Metzler, I., H. Krebbel, U. Kuckelkorn, U. Heider, C. Jakob, M. Kaiser, C. Fleissner, E. Terpos, and O. Sezer (2009). Curcumin diminishes human osteoclastogenesis by inhibition of the signalosome-associated I kappaB kinase. J Cancer Res Clin Oncol, 135.2: p. 173 – 9.
Kim, W.K., K. Ke, O.J. Sul, H.J. Kim, S.H. Kim, M.H. Lee, S.Y. Kim, H.T. Chung, and H.S. Choi (2011). Curcumin protects against ovariectomy-induced bone loss and decreases osteoclastogenesis. J Cell Biochem, 112.11: p. 3159 – 66.
D›Aiuto, F., L. Nibali, M. Parkar, K. Patel, J. Suvan, and N. Donos (2010). Oxidative stress, systemic inflammation, and severe periodontitis. J Dent Res, 89.11: p. 1241 – 6.
Nabavi, S.F., Daglia, M., Moghaddam, A.H., Moghaddam, S., Nabavi, S.M. (2014). Curcumin and Liver Disease: from Chemistry to Medicine. Comprehensive Reviews in Food Science and Food Safety, 13.p. 62 – 77.
Guimaraes, M.R., L.S. Coimbra, S.G. de Aquino, L.C. Spolidorio, K.L. Kirkwood, and C. Rossa, Jr. (2011). Potent anti-inflammatory effects of systemically administered curcumin modulate periodontal disease in vivo. J Periodontal Res, 46.2: p. 269 – 79.
Sugimoto, H., K. Watanabe, T. Toyama, S.S. Takahashi, S. Sugiyama, M.C. Lee, and N. Hamada (2014). Inhibitory Effects of French Pine Bark Extract, Pycnogenol, on Alveolar Bone Resorption and on the Osteoclast Differentiation. Phytother Res.
de Lima, V., M.M. Bezerra, V.B. de Menezes Alencar, F.D. Vidal, F.A. da Rocha, G.A. de Castro Brito, and R. de Albuquerque Ribeiro (2000). Effects of chlorpromazine on alveolar bone loss in experimental periodontal disease in rats. Eur J Oral Sci, 108.2: p. 123 – 9.
Goes, P., I.M. Melo, C.S. Dutra, A.P. Lima, and V. Lima (2012). Effect of alendronate on bone-specific alkaline phosphatase on periodontal bone loss in rats. Arch Oral Biol, 57.11: p. 1537 – 44.
Preiss, D.S. and J. Meyle (1994). Interleukin-1 beta concentration of gingival crevicular fluid. J Periodontol, 65.5: p. 423 – 8.
Cavanaugh, P.F., Jr., M.P. Meredith, W. Buchanan, M.J. Doyle, M.S. Reddy, and M.K. Jeffcoat (1998). Coordinate production of PGE2 and IL-1 beta in the gingival crevicular fluid of adults with periodontitis: its relationship to alveolar bone loss and disruption by twice daily treatment with ketorolac tromethamine oral rinse. J Periodontal Res, 33.2: p. 75 – 82.
Ouyang, W., S. Rutz, N.K. Crellin, P.A. Valdez, and S.G. Hymowitz (2011). Regulation and functions of the IL-10 family of cytokines in inflammation and disease. Annu Rev Immunol, 29.p. 71 – 109.
Gaddipati, J.P., S.V. Sundar, J. Calemine, P. Seth, G.S. Sidhu, and R.K. Maheshwari (2003). Differential regulation of cytokines and transcription factors in liver by curcumin following hemorrhage/resuscitation. Shock, 19.2: p. 150 – 6.
Sunagawa, Y., S. Sono, Y. Katanasaka, M. Funamoto, S. Hirano, Y. Miyazaki, Y. Hojo, H. Suzuki, E. Morimoto, A. Marui, R. Sakata, M. Ueno, H. Kakeya, H. Wada, K. Hasegawa, and T. Morimoto (2014). Optimal Dose-Setting Study of Curcumin for Improvement of Left Ventricular Systolic Function After Myocardial Infarction in Rats. J Pharmacol Sci.
Gukovsky, I., C.N. Reyes, E.C. Vaquero, A.S. Gukovskaya, and S.J. Pandol (2003). Curcumin ameliorates ethanol and nonethanol experimental pancreatitis. Am J Physiol Gastrointest Liver Physiol, 284.1: p. G85 – 95.
Morimoto, T., Y. Sunagawa, Y. Katanasaka, S. Hirano, M. Namiki, Y. Watanabe, H. Suzuki, O. Doi, K. Suzuki, M. Yamauchi, T. Yokoji, E. Miyoshi-Morimoto, Y. Otsuka, T. Hamada, A. Imaizumi, Y. Nonaka, T. Fuwa, T. Teramoto, H. Kakeya, H. Wada, and K. Hasegawa (2013). Drinkable preparation of Theracurmin exhibits high absorption efficiency--a single-dose, double-blind, 4-way crossover study. Biol Pharm Bull, 36.11: p. 1708 – 14.
Shishodia, S., G. Sethi, and B.B. Aggarwal (2005). Curcumin: getting back to the roots. Ann N Y Acad Sci, 1056.p. 206 – 17.
Cheng, A.L., C.H. Hsu, J.K. Lin, M.M. Hsu, Y.F. Ho, T.S. Shen, J.Y. Ko, J.T. Lin, B.R. Lin, W. Ming-Shiang, H.S. Yu, S.H. Jee, G.S. Chen, T.M. Chen, C.A. Chen, M.K. Lai, Y.S. Pu, M.H. Pan, Y.J. Wang, C.C. Tsai, and C.Y. Hsieh (2001). Phase I clinical trial of curcumin, a chemopreventive agent, in patients with high-risk or pre-malignant lesions. Anticancer Res, 21.4B: p. 2895 – 900.
Hsu, C.H. and A.L. Cheng (2007). Clinical studies with curcumin. Adv Exp Med Biol, 595.p. 471 – 80.
