Lecithin and linoleate were used as models for membranes and erythrocyte ghosts from rats as an example of real membranes. In a series of experiments, it was observed that organic and inorganic Se compounds, can scavenge peroxy radicals, which is preliminary in vitro evidence for A. L. Tappel's (1984) proposal. It is suggested that 2/3 of the Se may exert its biol. functions by directly acting as a scavenger of peroxy radicals. The scavenging effect of organic Se is greater than that of inorganic Se. Some of the organic forms exhibit the odd-even regularities. CNDO/2 calcns. indicated that it was quite possible for Se compounds to scavenge lipid peroxy radicals through Se radicals.

Key words: LIPOSOME, LINOLEIC ACID, CNDO APPROXIMATION, BIOMEMBRANE, ELECTRON SPIN RESONANCE, ULTRAVIOLET RADIATION, SELENIUM COMPOUNDS, PEROXIDE, RADICAL SCAVENGER, LECITHIN