Protective role of curcumin against nicotine-induced genotoxicity on rat liver under restricted dietary protein

Nicotine, the well known addictive chemical of tobacco and active medication for several diseases, has proven to be a potential genotoxic compound. Although it is absorbed through lungs with smoking and mainly metabolized in liver, its effect on liver injuries is not clear. This study was designed to evaluate the genotoxicity of nicotine and corresponding the protective role of curcumin against nicotine on liver of female populations particularly who used tobacco but deprived of healthy diet. The effects were investigated by measurement of total DNA concentration of liver tissues and Comet assay of liver tissue DNA damage of female rats maintained under normal and restricted protein diets. Total DNA contents in the liver tissues were observed to decrease more significantly (P<0.001) by nicotine in both dietary conditions. Significant (P<0.01) increase of total DNA content in normal dietary condition and more significant (P<0.001) increase of total DNA content in protein restricted condition of the liver tissues were observed due to curcumin supplementations. Highly significant (P<0.001) DNA damages (37% in normal diet and 56% in protein restricted diet) of the liver tissues were observed due to nicotine treatment. Curcumin reduced the nicotine-induced DNA damage percentage of the liver tissues more significantly (P<0.001) in protein restricted condition. Curcumin proved its potential to function against genotoxic effect by reducing the DNA damage activity of nicotine and minimized the percentage of DNA damage (50-60%) in protein restricted dietary condition. The degree of nicotine-induced genotoxicity therefore can be effectively compensated by the protective effect of curcumin in protein stress condition.