Synthesis, Characterization And Primary In Vitro And In Vivo Anti-tumor Evaluation Of Nctd-pva And Nctd-cs

Norcantharidin (NCTD), a derivative of cantharidin (CTD), remains theprototypic anticancer activity and alleviates the toxicity to urinary system.However, its low targeting efficiency and short circulation time limit itsapplication in clinic greatly. In this paper, two novel polymer-drug conjugatesnorcantharidin-poly (vinyl alcohol) and norcantharidin-chitosan (NCTD-PVAand NCTD-CS) were synthesized and their primary in vitro and in vivoantitumor activity was evaluated. The purpose is to deliver NCTD to tumorissue and remain there for a longer time via the enhanced permeability andretention (EPR) effect so as to enhance the tumor targeting efficiency andlessen the toxicity to normal tissues. The polymer-drug conjugates could alsoincrease the elimination period of NCTD in vivo, which provides the sustainedrelease possibility.Firstly, the NCTD-PVA and NCTD-CS were synthesized via alcoholysisreaction under appropriate reaction conditions. The1H NMR and FT-IR spectraindicated that NCTD-PVA and NCTD-CS were synthesized successfully. Thedegree of NCTD substitution (mol/monomer mol) of NCTD-PVA andNCTD-CS were10.4%and89.6%, respectively. Next, the release behavior ofNCTD-PVA and NCTD-CS was performed in PBS (pH7.4and5.0)respectively. The results showed that the lower the pH, the larger thehydrolysis rate, but NCTD-PVA could release NCTD much faster thanNCTD-CS did under the same conditions. Secondly, the in vitro evaluation of NCTD-PVA and NCTD-CS on humanesophageal carcinoma ECA-109cell was conducted. The evaluation mainlyincluded the MTT assay, cell cycle distribution assay, cell apoptosis assay andthe caspase3and caspase8activity assay. The data indicated that the twoconjugates both inhibited the proliferation of ECA-109cell, arrested cell at theS phase, induced cell apoptosis, up-regulated the activity of caspase3andcaspase8.Lastly, the in vivo evaluation of NCTD-PVA and NCTD-CS ontumor-bearing mice was performed. The results turned out that the tumorinhibition rates of the two conjugates were larger than that of free NCTD.However, the histologic sections showed that NCTD-PVA and NCTD-CS mayhave negative effects on spleen and kidney. So the safety evaluation of the twoconjugates still needs further investigation.