Biol. Pharm. Bull. 28(7) 1165—1171 (2005)

to treat a variety of malignacies, such as leukemias, breast and ovarian cancer, and Hodgkin and non-Hodgkin lymphoma. The major limitation of clinical use is the development of cardiotoxicity. The adverse effects are dose dependent and can vary from transient electrocardiographic abnormalities to cardiomyopathy and heart failure. Recent studies have suggested that the mechanism of DOX-induced cardiotoxicity involves the generation of reactive oxygen species (ROS), especially superoxide anion and hydrogen peroxide. The main cellular damage caused by ROS includes lipid peroxidation, protein cross-linking, and DNA fragmentation. These may lead to cardiac dysfunction, apoptosis, and development of cardiomyopathy. Although protection or alleviation of DOX toxicity can be achieved by administration of antioxidant vitamins such as ascorbic acid and vitamin E, their cardioprotective effects remain controversial. It is well established that there is no universal “best” antioxidant. For example, ascorbic acid efficiently protects against lipid damage but not against protein damage. Thus alternative naturally occurring antioxidants may potentially be candidates for antioxidant therapy. It has been shown in many studies that traditionally used plant extracts protect against oxidative damage caused by a wide array of insults including DOX. Among traditional herbs, Phyllanthus spp. (Euphorbiaceae) has been used in Aryuvedic medicine for more than 2000 years and in Thai folk medicine for the treatment of many diseases, such as diarrhea, hepatitis, diabetes, abdominal pain, and kidney disease. The antioxidant effects of plant species in the genus Phyllanthus have been reported. For example, Phyllanthus amarus (synonym: Phyllanthus niruri) reduced oxidative damage from radiation and protected against hepatotoxicity induced by CCl4. 20) Phyllanthus emblica protected rat hearts from oxidative stress induced by ischemic-reperfusion injury. Phyllanthus urinaria L. is another medicinal plant that has attracted research attention in the treatment of several diseases. Substantial progress in determining its phytochemical and pharmacologic properties has been made. Several potential antioxidant compounds (e.g., polyphenols, lignans, flavonoids, gallic acid, ellagic acid, etc.) have been isolated from this plant. However, to the best of our knowledge, there has been no report on the potential antioxidant effects of Phyllanthus urinaria. Therefore the purpose of this study was to investigate the antioxidant effects of Phyllanthus urinaria for the protection of cardiac cells from DOX cardiotoxicity.