Effects of peroxides on permeability and their modification by indoles, vitamin E, and other substances

Hydroperoxides can cause obvious injury, mutation, and death to cells and multicellular organisms (1, 19). At sufficiently low concentrations, their effects like that of ozone can be manifested in germination or growth rather than in obvious necrosis (7,20). The effects on germination of such active oxidants c;an be in part reversed by antioxidants such as indoles or cobaltous salts. Some of the effects of peroxides may be related to their facile attack upon thiol groups in simple molecules or proteins (5). Obviously, a gap exists between chemical effects and overall growth responses. Hence an effort was made to fill the gap at the cellular level. Some observations made on the permeability of beet root tissues, namely A) th;at thermal damage to the membrane is in fact oxidative in character (11) ; B) that exposure of plants to elevated Po, causes membrane breakdown and exudation even of protein (16); and C) that substantial increases in permeability induced by chem.ical means are correlated with loss in viability (13), suggested the following hypothesis: Peroxides at growth-inhibiting concentrations (10-5 10-3 M) should increase beet root membrane permeability; the relative effectiveness of various peroxides on permeability and loss in viability should be similar; and peroxidic damage to the membrane should be reversed, in part at least, by antioxidants. The results presented in this paper largely support this hypothesis.