curcumin and naphthalene

Naphthalene is a bicyclic aromatic compound that has wide industrial and commercial applications. It is used as the starting material for the synthesis of other compounds, as a moth repellent, soil fumigant and lavatory deodorant. Most exposure occurs through low dose chronic inhalation, dermal contact or ingestion through the food chain. The lungs and eyes appear to be most susceptible to toxicity, although biochemical markers of toxicity can be demonstrated in other tissues, such as the kidney, brain and liver. In addition to lens opacification (cataracts) and histological changes associated with pneumotoxicity, other biomarkers of toxic effects include glutathione depletion, lipid peroxidation, DNA fragmentation and the production of the active oxygen species as superoxide anion and hydroxyl radical. In addition, the urinary excretion of lipid metabolites occurs. A role for the tumor suppressor gene p53 has been demonstrated. Toxic manifestations of naphthalene are associated with its oxidative metabolism to various products including quinones. The ability to protect against the toxic effects of naphthalene by using various antioxidants and free radical scavengers has been demonstrated. Studies have been conducted with vitamin E, vitamin E succinate, melatonin, curcumin, various L-cysteine prodrugs, several aldose reductase inhibitors and spin-trapping agents. The ability to prevent the toxic manifestations of naphthalene is dependent on the pharmacokinetic properties of the agents, which have been studied. The appropriate selection of chemoprotectants can be useful in preventing naphthalene toxicity.

Topics: Animals; Antioxidants; CHO Cells; Cricetinae; Curcumin; Glutathione; Humans; Inhalation Exposure; Melatonin; Mice; Mice, Inbred C57BL; Naphthalenes; Oxidative Stress; Prodrugs; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Tocopherols; Vitamin E

Administration of naphthalene is known to cause cataract formation in rats and rabbits and naphthalene-initiated cataract is frequently used as a model for studies on senile cataract in humans. Oxidative stress has been implicated in the mechanism of naphthalene-induced cataract. Curcumin, a constituent of turmeric, a spice used in Indian curry dishes, is an effective antioxidant and is known to induce the enzymes of glutathione-linked detoxification pathways in rats. During the present studies, we have examined whether low levels of dietary curcumin could prevent naphthalene-induced opacification of rat lens. The presence of apoptotic cells in lens epithelial cells was also examined by catalytically incorporating labeled nucleotide to DNA with either Klenow fragment of DNA polymerase or by terminal deoxynucleotidyl transferase (TdT), which forms polymeric tail using the principle of TUNEL assay. The results of these studies demonstrated that the rats treated with naphthalene and kept on a diet supplemented with only 0.005% (w/w) curcumin had significantly less opacification of lenses as compared to that observed in rats treated only with naphthalene. Our studies also demonstrate, for the first time, that naphthalene-initiated cataract in lens is accompanied and perhaps preceded by apoptosis of lens epithelial cells and that curcumin attenuates this apoptotic effect of naphthalene.

Topics: Administration, Oral; Animals; Apoptosis; Cataract; Curcumin; Dietary Supplements; Epithelial Cells; Fluorescein; Lens, Crystalline; Male; Naphthalenes; Rats; Rats, Sprague-Dawley