Combination of porphyrins and DNA-alkylation agents: Synthesis and tumor cell apoptosis induction

Some cationic porphyrins: synthesis, stabilization of G-quadruplexes, and down-regulation of c-myc in Hep G2 cells

The stabilization of G-quadruplex DNA represents an attractive strategy for the design and development of novel antitumor drugs. In the present work, we have designed and synthesized nine cationic porphyrins, each with four side arms at their meso positions. The interactions of these porphyrins with both human telomeric DNA and NHE III1 G-quadruplexes were measured by various DNA binding assays, including polymerase stop assay, circular dichroism (CD) and CD melting assay. We then proceeded to investigate their effects on the expression of c-myc oncogene in the Hep G2 cell line. The experimental results indicate that these porphyrins are capable of effectively inducing or stabilizing both human telomeric and NHE III1 G-quadruplexes in the presence or absence of metal ions. Furthermore, we have discovered that porphyrins with a stronger stabilizing effect on c-myc G-quadruplexes lead to more pronounced down-regulation of the c-myc oncogene in the Hep G2 cell line.

Porphyrin-cyclodextrin conjugates as a nanosystem for versatile drug delivery and multimodal cancer therapy

The porphyrin-cyclodextrin conjugates were prepared and tested for selective and effective multifunctional drug delivery and therapy. The porphyrin receptor system combines efficient binding of the selected drug to the cyclodextrin cavity and photosensitizing properties of the porphyrin moiety with high accumulation of the whole complex in cancer tissue. The combined effect of chemotherapy and photodynamic therapy is demonstrated by in vitro and in vivo studies.

Quinone methides tethered to naphthalene diimides as selective G-quadruplex alkylating agents

We have developed novel G-quadruplex (G-4) ligand/alkylating hybrid structures, tethering the naphthalene diimide moiety to quaternary ammonium salts of Mannich bases, as quinone-methide precursors, activatable by mild thermal digestion (40 degrees C). The bis-substituted naphthalene diimides were efficiently synthesized, and their reactivity as activatable bis-alkylating agents was investigated in the presence of thiols and amines in aqueous buffered solutions. The electrophilic intermediate, quinone-methide, involved in the alkylation process was trapped, in the presence of ethyl vinyl ether, in a hetero Diels-Alder [4 + 2] cycloaddition reaction, yielding a substituted 2-ethoxychroman. The DNA recognition and alkylation properties of these new derivatives were investigated by gel electrophoresis, circular dichroism, and enzymatic assays. The alkylation process occurred preferentially on the G-4 structure in comparison to other DNA conformations. By dissecting reversible recognition and alkylation events, we found that the reversible process is a prerequisite to DNA alkylation, which in turn reinforces the G-quadruplex structural rearrangement.

Glycosyl bis-porphyrin conjugates: Synthesis and potential application in PDT

Syntheses of new glycosylated neutral and cationic porphyrin dimers linked at the meso-position via a flexible hydrocarbon chain are described. A detailed 1H and 13C NMR study allows their complete structural elucidation. The UV-visible, fluorescence and MALDI mass spectra are also presented. Photocytotoxicities of these compounds against K562 leukaemia cell line are compared to those of Photofrin II.