摘要：Aconityl-doxorubicin (ADOX) was synthesized by the modified method of Shen and Ryser. Two isomers of cis -ADOX ( cis -configuration) and trans -ADOX ( trans -configuration) were generated in the reaction of DOX and cis -aconitic anhydride. These products were separated completely by using HPLC and analyzed by TOF-MS spectroscopy and 1H- and 13C-NMR experiments. The yields of cis -ADOX and trans -ADOX were 36.3 and 44.8%, respectively. The free γ-carboxylic group of ADOX molecule was coupled to poly(vinyl alcohol) (PVA) via ethylenediamine spacer, resulting the macromolecular conjugates of PVA– cis -ADOX and PVA– trans -ADOX, respectively. The DOX content of the conjugates estimated by the hydrolysis method detected the aglycone of DOX which can be estimated as the PVA-bound DOX selectively was 4.4 w/w% which was similar to 4.6 w/w% by the ordinary UV method. Both PVA– cis -ADOX and PVA– trans -ADOX were very stable at neutral pH, but the release of DOX was increased markedly under acidic conditions. Half-life of the release of DOX from PVA– cis -ADOX at pH 5.0 was 3 h which was 4.7-fold shorter than that from PVA– trans -ADOX (14 h). The cytotoxicities of PVA– cis -ADOX and PVA– trans -ADOX were evaluated by using J774.1 cells employing a [3H]uridine incorporation assay as a measure of RNA synthesis. A significant difference in antitumor activity between PVA– cis -ADOX and PVA– trans -ADOX was observed where the former was much active than the later. It was suggested that the conjugate enters the cells and reaches the lysosomal/endosomal compartment, and that the aconityl spacer releases DOX from the conjugate in the acidic compartment of lysosomes/endosomes due to the participation of a free carboxylic group.
