Trypanocidal activity of arsonoliposomes: effect of vesicle lipid composition.

Sonicated arsonoliposomes were prepared using an arsonolipid with palmitic acid acyl chain (C16), mixed with phosphatidylcholine (PC-based) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC-based), and cholesterol (Chol) with a molar ratio C16 /PC or DSPC/ Chol 8:12:10. PEG-lipid (1,2-distearoyl-sn-glycero-3-phosphoethanolamine conjugated to polyethylenoglycol 2000) containing vesicles (pegylated-arsonoliposomes) were also prepared. The in vitro and in vivo trypanocidal activity of the various types of arsonoliposomes was evaluated. Although PC-based arsonoliposomes exhibited in vivo activity on an acute trypanosomiasis animal model, no evidence of activity was demonstrated for DSPC-based or pegylated-arsonoliposomes on a chronic model. Despite the fact that DSPC-based and pegylated-arsonoliposomes have better bioavailability compared to PC-based ones, their in vitro activity is lower than that of PC-based arsonoliposomes, indicating the importance of arsonoliposome lipid composition on their trypanocidal activity and suggesting that further arsonoliposome structure design is required to overcome these disadvantages.