Antitumor SOD Compounds

Abstract

Many studies have been recently performed on the activity of the enzyme superoxide dismutase (SOD) in tumor cells. This enzyme catalyzes the reaction $\\{20_2}^{\bar .}\; + \;2H\; \to {H_2}{0_2}\; + \;{0_2}\;(1)$. SOD is thought to be a protective enzyme necessary for life in all oxygen metabolizing cells (2). All normal eukaryotic cells (except the red blood cell) have both copper-zinc containing superoxide dismutase activity (Cu-ZnSOD) and manganese containing superoxide dismutase activity (MnSOD) (3). A typical pattern has emerged from the studies of SOD in tumor cells. Cancer cells have in general lowered activities of both Cu-ZnSOD and MnSOD when compared to their differentiated normal cell counterparts. Exceptions have been found to this pattern of low Cu-ZnSOD activity, but no exceptions have been found in the case of MnSOD activity. MnSOD activity has been found to be greatly reduced in over 50 human, rat, mouse, spontaneous, transplanted, virallyinduced, chemically-induced, in vivo, and in vitro tumors. This work has been the subject of a recent review (4).