The echinocytogenic and stomatocytogenic action on erythrocytes, the structure-modifying effect on erythrocyte membranes, and the hemolytic activity of IKhFAN antioxidants were established as functions of their hydrophobicity. The functions are nonlinear. The echinocytogenic, stomatocytogenic, and hemolytic activities first increase, pass through a maximum, and then decrease as the hydrophobicity parameter increases whereas the microviscosity of erythrocyte membranes varies in the opposite manner. These results may be useful in developing approaches to the synthesis of hybrid biologically active compounds including drugs with controlled and targeted delivery to the corresponding cell membrane structures.