Trypanocidal activity of free and carrier bound daunorubicin

Activities of a range of macromolecular conjugates of daunorubicin against Trypanosoma brucei rhodesiense in vitro and in vivo are described and compared to those of free daunorubicin. Conjugates tested were daunorubicin attached to bovine serum albumin by (i) a labile 'glutaraldehyde' linkage (D-BSAG), and (ii) a stable succinyl linkage (D-BSAS), daunorubicin covalently linked to agarose beads (D-AG), and daunorubicin adsorbed onto polyisobutylcyanoacrylate nanoparticles (D-PICA). Trypanocidal activity in vitro was retained in all except D-BSAS, whereas in vivo only D-BSAG had any activity. The results indicate that daunorubicin must be released from the conjugate before it can exert its activity.