Toxicity Study of a Novel Oral Iron Chelator: 1-(N-Acetyl-6-Aminohexyl)-3 Hydroxy-2-Methylpyridin-4-One (CM1) in Transgenic b-Thalassemia Mice

Abstract

Deferiprone (DFP) (MW=139 Da, Kpart=0.11) is an effective iron chelator used for the treatment of iron overload in thalassemia patients, but the drug is not free from side effects. We have synthesized a novel oral bidentate iron chelator, 1-(N-acetyl-6-aminohexyl)-3-hydroxypyridin-4-one (CM1) (MW=256 Da, Kpart=0.53), which is an analogue of DFP. This compound is more lipophilic than DFP and can bind iron efficiently. Our current results have demonstrated that CM1 reduced iron-induced redox damage and decreased levels of the intracellular iron pool (LIP) in cultured hepatocytes, effectively. However, the toxicity of CM1 remains largely unknown. The aim of this study was to therefore examine the toxicity of CM1 treatment in an animal model under normal and iron overload conditions. To induce iron overload, transgenic ß-thalassemia (BKO) mice were fed with a 0.2% (w/w) ferrocene-supplemented diet (Fe diet) for 240 days. The mice received three doses of CM1 orally (50,100 and 200 mg/kg), every day for 180 days. Blood was collected from the tail vein every 45 days during treatment for the measurement of hemoglobin (Hb) levels, white blood cells (WBC) and platelet numbers. We also determined the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP), which are markers of liver damage. Treatment with CM1 at the assigned doses did not markedly alter the numbers of WBC and the platelets, and the Hb level in BKO mice fed with either N diet or Fe diet. Importantly, all the treatments slightly increased the activities of plasma AST, ALT and ALP in BKO mice after 150 days. Nonetheless, hematoxylin and eosin staining results did not show abnormal morphological changes of the spleen, liver and heart tissues. The results imply that CM1 may not be toxic to bone marrow cells and liver cell function in BKO mice under normal and iron overload conditions.