Evaluation of the effects of curcumin on the hepatotoxicity induced by mercury in human HepG2 cells

Author(s)

Fabio Henrique Villa Pinto

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2015-06-10

Examining board members

Lusania Maria Greggi Antunes; Cátia Lira do Amaral; Maria Sol Brassesco Annichini

• Advisor: Lusania Maria Greggi Antunes

Abstract

Mercury is one of the most harmful metals present in the environment arising from both natural and anthropogenic sources. The individuals are exposed to different forms of mercury through various sources, such as food, especially in the case of methylmercury in fish, with this organic forms being very significant from a toxicological point of view, considering the exposure of the population and its pro-oxidant and genotoxic effects, involved in the origin of many diseases. On the other hand it is assumed that polyphenolic compounds and other dietary antioxidants can have protective activity against the harmful effects of mercury. Curcumin is a polyphenol extracted from the rhizome of Curcuma longa Linn. (Zingiberaceae). Several evidences show its ability to act as an antioxidant, modulate cell signaling and gene expression, and the possibility of its use in chemoprevention of the deleterious effects of metals. Therefore, this study aimed to evaluate the effects of the association between mercury and curcumin, investigating the cytotoxicity of two organic compounds of mercury, methylmercury and ethylmercury, and curcumin, alone and in combination, in HepG2 cells using the the MTT assay, the genotoxicity of these same compounds through the comet assay, the changes in oxidative state of the cells by the concentration of glutathione and GSH/GSSG ratio and the changes in the expression of 84 genes related to DNA damage anda repair pathways by PCR-Array. Organic mercury compounds showed cytotoxicity at concentrations equal to or greater than 16 uM. Curcumin only showed cytotoxicity at the concentration of 128 ?M. There was an increase in cytotoxicity when mercury (8 ?M) was associated with curcumin (64 ?M). In the genotoxicity assay there was a significant genotoxic of methyl mercury at concentrations of 8, 16 and 32 ?M while ethyl mercury whas genotoxic only at 32 ?M. Curcumin was not genotoxic. There was no anti-genotoxic activity in the association of compounds and there was an increase in genotoxicity of MeHg in association with 32 ?M of curcumin. The quantification of glutathione (GSH/GSSG) showed a significant increase in the GSH/GSSG ratio in cells treated with MeHg, however this was not observed when MeHg was associated with curcumin. Gene expression analysis showed changes in the expression of 26 genes, 3 of them were upregulated, DDIT3, GADD45A and PPP1R15A, mainly related to the cell cycle blockage and apoptosis, and 23 genes were down-regulated, related with DNA repair, cell cycle checkpoints and apoptosis. These results indicate that the combination of curcumin with mercury increased the deleterious effects of the metal, causing an increase in cytotoxicity and genotoxicity of mercury, and do not represent a possible strategy to prevent the harmful effects of mercury. (AU)

• FAPESP's process: 13/02922-2 - Evaluation of the effects of curcumin on mercury-induced hepatotoxicity in human cells HepG2
• Grantee: Fabio Henrique Villa Pinto
• Support Opportunities: Scholarships in Brazil - Master