ENHANCEMENT BY TAMOXIFEN OF THE MEMBRANE ANTIOXIDANT ACTION OF THE YEAST MEMBRANE STEROL ERGOSTEROL - RELEVANCE TO THE ANTIYEAST AND ANTICANCER ACTION OF TAMOXIFEN

The anticancer drug tamoxifen inhibits lipid peroxidation in ox-brain phospholipid liposomes, and is a good antiyeast agent, with clinical p otential. We now report that the ergosterol-containing lipid fraction derived from yeast microsomal membranes (and the ergosterol separated from it) inhibited lipid peroxidation when introduced into ox-brain ph ospholipid liposomes. Inhibition of lipid peroxidation by the lipid fr action was greatly enhanced when yeast cell growth was inhibited with tamoxifen prior to lipid extraction. The ability of tamoxifen to enhan ce the membrane antioxidant ability of ergosterol is expressed in term s of a tamoxifen enhancement coefficient. Enhancement by tamoxifen of the membrane antioxidant action of ergosterol is discussed in relation to the antifungal and anticancer actions of tamoxifen.