New Peptidyl-Anthraquinones: Synthesis and DNA Binding

Deciphering the Binding Insights of Novel Disubstituted Anthraquinone Derivatives with G-Quadruplex DNA to Exhibit Selective Cancer Cell Cytotoxicity

Anthraquinone-based compounds are well-known as duplex DNA as well as G-quadruplex DNA binders. Implications of various anthraquinone derivatives for specific recognition of G-quadruplex DNA over duplex DNA is a 'challenging' research work that requires adequate experience with molecular design. To address this important issue, we designed and synthesized ten new 2,6-disubstituted anthraquinone-based derivatives with different functionalized piperazinyl side-chains. Among these, particular compounds with certain distant groups have shown selective and significant binding affinities toward the c-MYC and c-KIT G-quadruplex DNA over the duplex DNA, as noticed from various biophysical experiments. The structural difference of quadruplex and duplex DNA was utilized to probe these derivatives for the end-stacking mode of binding with G-quadruplex DNA. The ability of the ligands to halt DNA synthesis by stabilizing G-quadruplex structures is one of the crucial points to further apply them for quadruplex-mediated anti-cancer therapeutics. Interestingly, these ligands trigger apoptosis to exhibit selective cytotoxicity toward cancer cells over normal cells. This was further evidenced by ligand-induced cell cycle arrest as well as cellular apoptotic morphological changes. These blood-compatible ligands provided detailed structure-activity relationship approaches for the molecular design of anthraquinone-based G-quadruplex binders.

Synthesis and biological evaluation of some differently substituted 9,10-anthracenediones

9,10-Anthracenedione derivatives are known to exhibit a quite potent anticancer activity. It has also been reported that these compounds can be effectively employed in both antibacterial and antitrypanosomal therapy. Anthraquinones also exhibit some undesirable side effects, like cardiotoxicity. So many interactions seem to demonstrate that 9,10-anthracenediones strongly interact with a number of biological sites. In this paper we wish to report on the synthesis and the pharmaceutical activity of some newly synthesised derivatives containing the anthraquinone pharmacophore.

New 1,4-anthracene-9,10-dione derivatives as potential anticancer agents

The amino-substituted anthracene-9,10-dione (9,10-anthraquinone) derivatives represent one of the most important classes of potential anticancer agents. To better understand the basic rules governing DNA sequence specificity, we have recently synthesized a new class of D- and L-aminoacyl-anthraquinone derivatives. We have tested these new compounds as cytotoxic agents, and we have correlated their activity with the configuration of the chiral aminoacyl moiety. Molecular modeling studies have been performed to compare the test drugs in terms of steric overlapping.

Cleavage of abasic sites in DNA by intercalator-amines

Anthraquinone and naphthalene diimide intercalators with amine-containing side chains cleave plasmid DNA at abasic sites (apurinic or apyrimidinic (AP) sites). The intercalator-amine is substantially more effective than the amine itself; many intercalators with diamine side chains cleave most of the abasic sites at micromolar concentration (30 min at 37 degrees C). Intercalators with two amino moieties in the side chain are more efficient than those with one, arguing for a role for each of two amines in the cleavage mechanism. Side chains ending in tertiary amines are somewhat more effective than those ending in primary amines, indicating that imine formation is not required for cleavage at the abasic site. We also report a systematic study of abasic site cleavage by polyamines, including piperidine, spermine, spermidine and 12 other di-, tri- and tetra-amines. For polyamines as well as intercalator-amines, examples with three carbon atoms between neighboring nitrogens atoms cleave most efficiently. This may reflect a particularly favorable geometry for proton abstraction for these species. The effect of nitrogen-nitrogen spacing on the pKa values of the nitrogens may contribute as well. Overall, cleavage of plasmid DNA at adventitious abasic sites by intercalator-amines bearing two nitrogens in a single side chain occurs readily.