Preparation, characterization and in vitro release study of a glutathione-dependent polymeric prodrug Cis-3-(9H-purin-6-ylthio)-acrylic acid-graft-carboxymethyl chitosan

In this work, an amphiphilic polymeric prodrug Cis -3-(9H-purin-6-ylthio)-acrylic acid-graft-carboxymethyl chitosan (PTA- g -CMCS) was designed and synthesized. In aqueous solution, this grafted polymer can self-assemble into spherical micelles with a size ranging from 104 to 285   nm and zeta potential ranging from −12.3 to −20.1   mV. For the release study, less than 24% of 6-Mercaptopurine (6-MP) was released from PTA- g -CMCS1 in the media containing 2 and 100   μM glutathione (GSH), whereas 37%, 54% and 75% of 6-MP was released from the media with GSH of 1, 2 and 10   mM, respectively. Besides, pH and drug content of the polymeric prodrug only presented slight influence on the 6-MP release. MTT assay demonstrated that this system had higher inhibition ratio on HL-60 cells (human promyelocytic leukemia cells) in the presence of GSH and lower cytotoxicity on mouse fibroblast cell line (L929). Therefore, this nano-sized system is glutathione-dependent, and it can be employed as a potential carrier for the controlled release of 6-MP.