Protein binding of anthraquinone glycosides, with special reference to adriamycin

The binding of anthraquinone glycosides (adriamycin, adriamycinol, daunorubicin, daunorubicinol, and 4'epiadriamycin) to human serum albumin and human plasma has been studied by equilibrium dialysis. About 62% of adriamycin was bound to human serum albumin (45 g/l). Only minor variations in the degree of binding were observed between the anthraquinone glycosides. The binding degree of adriamycin in plasma from cancer patients was not significantly different from that observed in healthy volunteers, the fraction of free adriamycin being 24.56% +/- 4.51%, and 27.67% +/- 2.78%, respectively. The plasma albumin concentration was significantly lower in cancer patients than in the healthy volunteers (26.90% +/- 5.88% and 39.24% +/- 1.74%, respectively). In cancer patients the fraction of free adriamycin decreased with increasing plasma albumin concentration.