Effects of alpha-tocopherol analogs on lysosome membranes and fatty acid monolayers.

The surface pressures of alpha-tocopherol analogs, fatty acids, and their mixtures were measured in their spread monolayers at an air--water interface. The surface pressure--area isotherms for the mixed monolayers of alpha-tocopherol and either stearic acid, oleic acid or linoleic acid deviated positively from those calculated on the basis of the additivity rule, and the magnitude depended on the length of the phytyl side chain in alpha-tocopherol and on the degree of unsaturation of the fatty acid chains. Lysosome membranes of mouse liver were stabilized by addition of alpha-tocopherol. A decrease in the length of the phytyl side chain in alpha-tocopherol reduced its ability to stabilize lysosome membranes. A good correlation was obtained between the extent of stabilizing activity of alpha-tocopherol analogs on lysosome membranes and the degree of positive deviation of the surface pressure for their mixtures with fatty acids.