Synthesis of Poly(vinyl alcohol)-Doxorubicin Conjugates Containing cis-Aconityl Acid-Cleavable Bond and Its Isomer Dependent Doxorubicin Release

Abstract

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 1 H-and 13 C-NMR experiments. The yields of cis-ADOX and trans-ADOX were 36.3 and 44.8%, respectively. The free g g-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 [ 3 H]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.

Synthesis of a Covalent Epirubicin-(C3-amide)-Anti-HER2/neuImmunochemotherapeutic Utilizing a UV-Photoactivated Anthracycline Intermediate

“…The covalent bond-forming reagent, cis-aconitic anhydride 29,34,40,61,[94][95][96] promotes covalent acylation at the C 3 monoamine group found within the anthracycline carbohydrate moiety (daunosamine -NH 2 -3¢) whereby it creates cis-and trans-isomers of N-cis-aconityl-anthracycline. 37,40,61,95,97 In practice, cis-aconitic anhydride has been used to synthesize both doxobucin 29,35 and daunorubicin 34,35 covalent immunochemotherapeutics. Similar to dextran and glutaraldehyde, cis-aconitic anhydride forms covalent bonds with immunoglobulin fractions at the e-amine group (R-NH 2 ) of lysine amino acid residues 97 but is associated with several of the same disadvantages experienced with many other homobifunctional cross-linking agents.…”

Targeted delivery of doxorubicin-utilizing chitosan nanoparticles surface-functionalized with anti-Her2 trastuzumab

“…Although covalent conjugation of doxorubicin to chitosan weakens its anticancer activity, antibody-conjugated nanoparticles were shown to discriminate between Her2 + and Her2 − cells and thus have potential applications in active targeted drug delivery and reduction of drug side effects in Her2 + breast and ovarian cancers. However, substitution of succinic anhydride with a pH-sensitive crosslinker like cisaconityl anhydride [40][41][42] or hydrazone bonds 43,44 may be taken into consideration in future studies to achieve an actively targeted vector releasing its cargo drug at its site of action. …”

Inhibition of tetramethylpyrazine on P-gp, MRP2, MRP3 and MRP5 in multidrug resistant human hepatocellular carcinoma cells

“…The mobile phase consisted of acetonitrile-water with KH 2 PO 4 (pH 3.0 adjusted with H 3 PO 4 ) (75:25, v/v), with a flow rate of 0.8 ml·min -1 . The wavelength of ADM detected was 233 nm (20,21).…”