Delivery systems for DNA-binding drugs as gene expression modulators

New poly(ester-amide) copolymers modified with polyether (PEAE) for anticancer drug encapsulation

New poly(ester-amide) copolymers modified with polyethers were developed for carboplatin encapsulation. These new copolymers contain hydrophobic blocks made of tyrosine derivative and dimer fatty acid, and poly(ethylene glycol) (PEG) as hydrophilic blocks. Short-term hydrolytic degradation revealed high water absorption, slight increase of pH of simulated body fluid and change of sample shape, which indicated the erosive mechanism of polymers degradation. Poly(ester-amide)-PEG copolymers were used for microspheres preparation and carboplatin encapsulation. A double emulsification process was used to produce microspheres with an average diameter of 20-30 μm. It was found that the amount of drug released was controlled by the molecular mass of PEG used for microspheres preparation. Mathematical models were used to elucidate the release mechanism of the carboplatin from the microspheres. The results demonstrate that poly(ester-amide)-PEG copolymers may be used for targeted carboplatin encapsulation and release.

Antiproliferative activity of novel thiopyran analogs on MCF-7 breast and HCT-15 colon cancer cells: synthesis, cytotoxicity, cell cycle analysis, and DNA-binding

A series of 6H-thiopyran-2,3-dicarboxylate derivatives 4a-d were synthesized and evaluated for their cytotoxic effect against HCT-15 colon and MCF-7 breast cancer cell lines using Sulforhodamine B (SRB) assay. The results showed that these compounds could exhibit a good cytotoxicity to both cell lines. In addition, these compounds were found to exhibit significant DNA-binding affinity. Ultraviolet-visible light (UV-Vis) spectroscopy was conducted to determine the ability of the ligand under analysis. The effect of ligand complexation on DNA structure led to overall affinity constants of K(4a)=3.5×10(4) M(-1), K(4b)=6.4×10(4) M(-1), K(4c)=3.2×10(4) M(-1), and K(4d)=2.4×10(4) M(-1). Our findings could provide new evidence showing the relationship between the chemical structure and biological activity and may be useful for the discovery of new anti-cancer drugs.

Mixed self-assembly of poly(ethylene oxide)-b-poly(epsilon-caprolactone) copolymers and sodium dodecyl sulfate in aqueous solution

Interaction of amphiphilic poly(ethylene oxide)-b-poly(epsilon-caprolactone) copolymers with anionic sodium dodecyl sulfate (SDS) has been investigated in aqueous solution. Formation of mixed micelles has been confirmed by surface tension measurements, whereas the influence of the surfactant on the copolymer self-assembling has been studied by measurement of the 1H NMR self-diffusion coefficients and by small-angle neutron scattering. As a rule, the surfactant decreases the heterogeneity of the micellar structures formed by the copolymer in water. Moreover, increasing the content of SDS results in the increasingly more important extension of the poly(ethylene oxide) (PEO) corona chains and the copolymer micelle deaggregation. The stability of the micelles against SDS increases with the length of the hydrophobic block. Preliminary two-dimensional NMR measurements with nuclear Overhauser enhancement have confirmed the spatial vicinity between SDS and the constitutive blocks of the copolymer.