Relation of the Characteristic Action of Biscoclaurine Alkaloids on the Erythrocyte Membrane and Their Incorporation into the Membrane

Abstract

In vitro effects of biscoclaurine alkaloids [antitumor, antihemolytic and membrane stabilizing compounds] on cell morphology and the osmotic resistance of human erythrocyte membranes were examined in relationship to their incorporation into the membrane. All alkaloids tested induced invaginational type of transformation and a change in resistance against hypotonic hemolysis as a function of the concentration, within a range of 10-5 M to 2 .times. 10-4 M, in the medium. Alkaloids were incorporated dose-dependently into cells in the same concentration range; the major part of the incorporation was in the membrane fraction. The effects of the alkaloids on the membrane and their affinity for the membrane, judged by the amount incorporated, decrease as follows: tetrandrine > cepharanthine > berbamine. Fangchinoline and isotetrandrine had an invaginating effect similar to that of cepharanthine. The shape-transforming effect of cepharanthine was antagonistic to that of snake venom phospholipase A2 which induced crenation of the cells by hydrolyzing the outer layer phospholipids of the lipid bilayer of the membrane. This alkaloid did not inhibit the hydrolytic action of the enzyme on the membrane. The biological action of the alkaloids on the erythrocyte membrane may be due to their interaction with the lipid bilayer of the membrane.