Curcumin reduces the toxic effects of iron loading in rat liver epithelial cells.
OBJECTIVE
Iron overload can cause liver toxicity and increase the risk of liver failure or hepatocellular carcinoma in humans. Curcumin (diferuloylmethane), a component of the food spice turmeric, has antioxidant, iron binding and hepatoprotective properties. The aim of this study was to quantify its effects on iron overload and the resulting downstream toxic effects in cultured T51B rat liver epithelial cells.


METHODS
T51B cells were loaded with ferric ammonium citrate (FAC) with or without the iron delivery agent 8-hydroxyquinoline. Cytotoxicity was measured by methylthiazolyldiphenyl-tetrazolium bromide assay. Iron uptake and iron bioavailability were documented by chemical assay, quench of calcein fluorescence and ferritin induction. Reactive oxygen species (ROS) were measured by a fluorescence assay using 2',7'-dichlorodihydrofluorescein diacetate. Oxidative stress signalling to jnk, c-jun and p38 was measured by a Western blot with phospho-specific antibodies.


RESULTS
Curcumin bound iron, but did not block iron uptake or bioavailability in T51B cells given FAC. However, it reduced cytotoxicity, blocked the generation of ROS and eliminated signalling to cellular stress pathways caused by iron. Inhibition was observed over a wide range of FAC concentrations (50-500 microM), with an apparent IC(50) in all cases between 5 and 10 microM curcumin. In contrast, desferoxamine blocked both iron uptake and toxic effects of iron at concentrations that depended on the FAC concentration. The effects of curcumin also differed from those of alpha-tocopherol, which did not bind iron and was less effective at blocking iron-stimulated ROS generation.


CONCLUSIONS
Curcumin reduced iron-dependent oxidative stress and iron toxicity in T51B cells without blocking iron uptake.
Messner
Donald J
DJ
Bastyr University Research Center, Bastyr University, Kenmore, WA 98028, USA. dmessner@bastyr.edu
Sivam
Gowsala
G
Kowdley
Kris V
KV
D000818:Animals; D002478:Cells, Cultured; D003474:Curcumin / Q000378:metabolism / Q000494:pharmacology*; D003676:Deferoxamine / Q000378:metabolism / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005290:Ferric Compounds / Q000493:pharmacokinetics / Q000633:toxicity*; D020128:Inhibitory Concentration 50; D008099:Liver / Q000166:cytology / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects*; D000644:Quaternary Ammonium Compounds / Q000493:pharmacokinetics / Q000633:toxicity*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013778:Tetrazolium Salts; D013844:Thiazoles
D005290:Ferric Compounds; D000644:Quaternary Ammonium Compounds; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; C022616:thiazolyl blue; D003474:Curcumin; D003676:Deferoxamine; C013531:ferric ammonium citrate