SUBSTITUTED ANTHRAQUINONES IN G4-DNA DRUG DESIGN: A CONCISE REVIEW

Abstract DNA in the human telomere in the form of G-quadruplex (G4) has become an interesting target in cancer therapy since it plays a regulatory role in keeping the telomeres stable and regulating telomerase activity. Compounds consisting of anthraquinone-based structure and that have shown a high affinity to DNA due to the planar aromatic scaffold and the potentiality of binding G-quadruplex structures, have extensively been drawn as potent starting points to selectively stabilize G-quadruplex structures that occur in telomeres. The review indicates the latest achievements in the design, synthesis, and biological testing of the anthraquinone derivatives specifically oriented to act against human telomeric G4 DNA. A number of changes-amino-alkyl side chain, dimeric structures, and sugar conjugates- have enhanced their binding affinity and selectivity to duplex DNA and ability to kill cancer cells considerably. The derivatives, including 2,6-disubstituted-amino alkyl-amido, anthraquinones with neomycin-anthraquinone conjugates, can be mentioned as the derivatives capable of nanomolar to micromolar affinities toward G4-DNA and the capability to inhibit telomerase in vitro. Strong binding interactions and thermal stability of G4 structures, in particular, with the monovalent salt ions, such as Na+ and K+, are likewise well-documented by biophysical methods, including UV-Vis’s spectroscopy, circular dichroism and fluorescence titrations. Cellular assays also show high therapeutic potentials of these compounds, which show reactive oxygen species (ROS), DNA damage and apoptosis in cancer cell lines. In addition to telomeric sequences, a few anthraquinone derivatives inhibit oncogene promoter G-quadruplexes extending the scope of their utility. Although the in vitro findings are encouraging, there are issues with regard to improved selectivity, toxicity and effective in vivo delivery. This review sums up the recent developments and provides future prospects of possible development of clinically useful G-quadruplex targeting anthraquinone therapeutics.