Fluorescence Spectroscopy in Camptothecins Studies

The application of fluorescence spectroscopy methods to determining the properties of analogues of camptothecin, promising anticancer agents, are described in this paper. The fluorescence anisotropy measurements provide useful information about the binding of camptothecin and its analogues to cell membranes and human serum albumin (HSA) that is important for potential clinical applications of these agents, and permit the selection from many camptothecin analogues those ones exhibiting desirable biomedical properties. Fluorescence anisotropy measurements prove that 3 new camptothecin analogues: 7-tert-butyldimethylsilyl-10-hydroxy-campthothecin, 7-trimethyl-silylethyl-10-hydroxy-camptothecin and 7-trimethyl-silyl-ethyl-10-amino-camptothecin exhibit high affinity of their lactone forms to membranes and low affinity of their carboxylate forms to HSA. Such properties should ensure high stability of these agents in physiological fluids, including blood.