In vitro binding studies of the peroxisomicine A1-BSA and -HSA interactions

Peroxisomicine Al (PA1) is a dimeric hydroxyanthracenone isolated from fruits of plants belonging to the genus Karwinskia. Showing selective toxicity between malignant and benign cell lines, it is currently under screening as an antineoplastic agent. Very little is known about its mechanism of action. In the present work the extent of binding of this substance with Bovine Serum Albumin (BSA) and Human Serum Albumin (HSA) at pH 7.2 and 7.4 has been evaluated using the spectrophotometric method. Absorbance of PAI was altered by the presence of albumin and this property was used to generate binding isotherms. The investigation was carried out at four different temperatures. The data were analyzed by assuming two types of binding sites. Results indicated that PAI binds to both albumins at physiological pH, which is reflected by the affinity constants of the order of 10(5). There are two types of binding sites in the albumin for PAI; with the electrostatic forces being discarded, the hydrophobic and hydrogen bond are more probable. Binding with HSA is stronger than with BSA. (C) 2001 Elsevier Science B.V. All rights reserved.