In vitro cytogenetic and genotoxic effects of curcumin on human peripheral blood lymphocytes

Abstract

Curcumin has shown a wide range of properties such as anti-inflammatory and anti-carcinogenic properties. Many of these effects, mainly the anti-carcinogenic effect, could be linked to its anti-oxidant effects. Nevertheless, some studies suggest that this natural compound possesses both pro- and anti-oxidative effects and that curcumin could be a genotoxic agent for some cell lines. We evaluated the genetic damage induced by curcumin to human lymphocytes exposed to increasing concentrations (0–50 μg/ml) of curcumin. Biomarkers such as chromosome aberrations (CAs) and sister chromatid exchange (SCE) were analyzed. In addition to the cytogenetic analysis, the effect of curcumin in the cell proliferation kinetics (CPK) by the proliferation index (PI) was also analyzed. The results indicated that high concentrations of curcumin induced CAs, mainly acentric fragments. SCEs rate was not statistically different from the control group in any curcumin treated cell group. The PI of cells treated with 2 and 5 μg/ml of curcumin were statistically significant from the control group and finally, the MI showed a tendency to increase in all the concentrations of curcumin tested. In conclusion, it can be assumed that the higher concentrations of curcumin evaluated have a cyto and genotoxic effect, in vitro, for human peripheral lymphocytes.

Introduction

Curcumin (1,7-bis (4-hydroxy-3-methoxyphenol)-1,6-heptadiene-3,5-dione) is a major polyphenolic compound isolated from the rhizomes of turmeric (Curcuma longa) (Aftab and Vieira, 2010). Since the time of the old Asian medicine curcumin has been used in the practice for the treatment of common cold, skin diseases, wound healing, inflammation etc. (Sebastià et al., 2012, Kunwar et al., 2008). In the last half century hundreds of scientific publications have confirmed its anti-oxidant, anti-inflammatory, antibacterial, antiparasitary or antiamyloid properties. Related to its anti-inflammatory properties, curcumin has been classified as a natural agent with strong therapeutic potential against a variety of cancers showing the suppression of the transformation, proliferation, and metastasis of tumours (Shishodia et al., 2007). In contrast to these studies some reports suggest that curcumin, among others polyphenols, shows DNA damaging properties in cells suggesting that curcumin exhibits both anti-oxidant and pro-oxidant activities in different cell lines (Banerjee et al., 2008). This ability of some plant-derived polyphenols is due to the fact that they can also act as pro-oxidants catalyzing cellular DNA degradation in the presence of transition metal ions such as copper (Bhat et al., 2007). Some studies have proposed that the pro-oxidant action of plant polyphenolics may be an important mechanism of their anticancer and apoptosis inducing properties (Hadi et al., 2007). This pro-oxidant action should also be considered in normal cells lines, i.e. in the study of Cao et al. (2006) it was observed that curcumin, at high doses, imposed oxidative stress and damaged the DNA of HepG2 cells. This study and others suggest that the pro-oxidant/anti-oxidants activities of many compounds still remain unclear (Cemeli et al., 2009) and that before a substance is claimed to have antigenotoxic/antimutagenic effects, it should also be evaluated for genotoxicity and rigorously tested with appropriate protocols (Mendonça et al., 2009).

Cytogenetic alterations in peripheral blood lymphocytes, such as chromosomal aberrations (CAs) and sister chromatid exchanges (SCE) have long been applied in surveillance of human genotoxic exposure and early effects of genotoxic carcinogens. The use of these biomarker assays is based on the fact that most established human carcinogens are genotoxic in short-term tests and capable of inducing chromosomal damage. On the one hand, chromosomal aberrations have been used as important cytogenetic biomarkers to study the mutagenic effects of different chemicals in vivo and in vitro (Sutiaková et al., 2012). The relevance of CAs as a biomarker has been further emphasized by epidemiological studies suggesting that a high frequency of chromosomal aberrations is predictive of an increased risk of cancer, (Bonassi et al., 2008). On the other hand, SCE is a highly sensitive parameter for evaluating human occupational and environmental exposure to mutagenic and carcinogenic agents (Norppa et al., 2006). Moreover, parameters such as Mitotic Index (MI) and Cell Proliferation kinetics (CPK) have been proposed as useful biomarkers for the pre-screening of the potential cytostatic activity of new drugs (Rojas et al., 1993). The use of the cell proliferation kinetics and the mitotic index are recognized biomarkers in biological monitoring to evaluate lymphocyte proliferation in population as well as to evaluate normal or tumour cells (Rojas et al., 1993).

Using the cytogenetic parameters mentioned, the aim of this study was to evaluate the possible cytogenetic and genotoxic effects of curcumin on cultured human peripheral lymphocytes in vitro.