Preparation, Characteristics and Toxicity of Ricin-containing Galactosyl Ceramide Liposomes.

Ricin-containing galactosyl ceramide liposomes (ricin-GCLs) lyophilized product was made by the dehydration-rehydration vesicles(DRV) method and its toxicity to human heptocarcinoma cell line 7721 and to mice was investigated. The results indicated that the maximum encapsulation efficiency of ricin was 74.1%. The distribution of ricin-GCLs' sizes accords with intravenous injection standard and changes little in half a year at 4 degrees. In the cytotoxicity assay, the ratio of ricin-GCLs' to free ricin's IC50 was 1.00:3.89, which indicated that the ricin entrapped in GCLs was more effective than the free one in killing human heptocarcinoma cell line 7721. In vivo, the mice's LD(50) of ricin-GCLs ((41.8+/-9.33) &mgr;g/kg)is more than that of free ricin ((30.6+/-8.49) &mgr;g/kg) by 36.29%. So, ricin entrapped in GCLs promotes its cytotoxicity and reduces its toxic side-effect.