Comparative evaluation of antioxidant potential of alaternin (2-hydroxyemodin) and emodin

The antioxidant activities of alaternin (2-hydroxyemodin) and emodin were c ompared for their respective potentials to inhibit lipid peroxidation in th e linoleic acid system by the thiocyanate method, to inhibit total reactive oxygen species generation in kidney homogenates using 2',7'-dichlorodihydr ofluorescein diacetate, to inhibit peroxynitrite formation by the 3-morphol inosydnonimine system, which generates superoxide radical and nitrogen mono oxide, and to scavenge authentic peroxynitrites. Both alaternin and emodin were found to inhibit the peroxidation of linoleic acid by the thiocyanate method in a dose-dependent manner. Whereas the former shows inhibitory acti vities in reactive oxygen- and nitogen-mediated reactions, the latter does not. These results indicate that alaternin is a potentially effective and v ersatile antioxidant and can be used to protect biological systems and func tions against various oxidative stresses.