Antitumor activity and pharmacokinetics of podophyllotoxin incorporated into solid lipid nanoparticles

Manipulation of pH-Sensitive interactions between podophyllotoxin-chitosan for enhanced controlled drug release

Podophyllotoxin (PPT) offers a broad-spectrum of anticancer activities, but little has been reported for its controlled release. This work shows that by manipulating molecular interactions between PPT and Chitosan, efficient nanoscale capsulation of PPT can be realized. The drug encapsulation efficiency is as high as 52%, with a final particle drug loading in the order of 10% (wt/wt). It further demonstrates that changes in pH can also significantly affect the rate of drug release from the Chitosan nanoparticles. Upon contact with cancer cells, chitosan nanoparticles enable efficient internalization and drug release. In vitro evaluations with HepG-2 and MCF-7 cells indicate that the chitosan nanoparticle carriers can improve drug efficacy in comparison to free PPT, most likely by regulating the intrinsic apoptotic signaling pathway to induce apoptosis. Overall, PPT chitosan nanoparticles promise a safe and efficient drug delivery system for PPT.

pH-responsive polymer-drug conjugates as multifunctional micelles for cancer-drug delivery

We developed a novel linear pH-sensitive conjugate methoxy poly(ethylene glycol)-4β-aminopodophyllotoxin (mPEG-NPOD-I) by a covalently linked 4β-aminopodophyllotoxin (NPOD) and PEG via imine bond, which was amphiphilic and self-assembled to micelles in an aqueous solution. The mPEG-NPOD-I micelles simultaneously served as an anticancer drug conjugate and as drug carriers. As a drug conjugate, mPEG-NPOD-I showed a significantly faster NPOD release at a mildly acidic pH of 5.0 and 4.0 than a physiological pH of 7.4. Notably, it was confirmed that this drug conjugate could efficiently deliver NPOD to the nuclei of the tumor cells and led to much more cytotoxic effects to A549, Hela, and HepG2 cancer cells than the parent NPOD. The half maximal inhibitory concentration (IC₅₀) of mPEG-NPOD-I was about one order magnitude lower than that of the NPOD. In vivo, mPEG-NPOD-I reduced the size of the tumors significantly, and the biodistribution studies indicated that this drug conjugate could selectively accumulate in tumor tissues. As drug carriers, the mPEG-NPOD-I micelles encapsulated hydrophobic PTX with drug-loading efficiencies of 57% and drug-loading content of 16%. The loaded PTX also showed pH-triggered fast release behavior, and good additive cytotoxicity effect was observed for the PEG-NPOD-I/PTX. We are convinced that these multifunctional drug conjugate micelles have tremendous potential for targeted cancer therapy.