Synthesis and in Vitro Evaluation of Novel 5-Nitroindole Derivatives as c-Myc G-Quadruplex Binders with Anticancer Activity

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.

New Bioactive Aromatic Heterocyclic Macromolecules with Monosaccharide Core

1,1,2-trimethyl-1H-benzo[e]indole is an important heterocyclic compound, its available in reasonable price and can easily modified to make a good intermediate for other derivatives. That is quite enough reasons to use as starting material for a new series of compounds with other biomolecules such as monosaccharides after simple modification. The target molecules show biological activity. So, the current work is aiming to improve the activity and the properties of the benzo indole by attaching with a naturally occurring, and biodegradable compounds represented by 2-deoxy-2-amino -d-glucose and 6-deoxy-6-amino-d-glucose to synthesis both mono and di-saccharides derivatives of benzo indole. Two steps synthesis were used for mono-saccharide derivatives and three steps for di-saccharide derivatives, the first is the functionalization of 1,1,2-trimethyl-1H-benzo[e]indole [1] via the reaction with POCl3 to produce 2-(1,1-dimethyl-1H-benzo[e]indol-2(3H)-ylidene) malonaldehyde [2] with two aldehydes reaction centers, while in the second step the latter was coupled with sugar via amino groups to get the two monosaccharide derivatives [3,5], while the disaccharides molecules [4,6] taken one more step with harder conditions to overcome the steric hindrance at the other reaction center. The purity and characterization of the target molecules was confirmed using spectroscopy methods including 1H NMR and 13 NMR. The synthesized compound shows a good biological activity as antibacterial antifungal.

Synthesis and in Vitro Evaluation of Novel 5-Nitroindole Derivatives as c-Myc G-Quadruplex Binders with Anticancer Activity

Lead-optimization strategies for compounds targeting c-Myc G-quadruplex (G4) DNA are being pursued to develop anticancer drugs. Here, we investigate the structure-activity- relationship (SAR) of a newly synthesized series of molecules based on the pyrrolidine-substituted 5-nitro indole scaffold to target G4 DNA. Our synthesized series allows modulation of flexible elements with a structurally preserved scaffold. Biological and biophysical analyses illustrate that substituted 5-nitroindole scaffolds bind to the c-Myc promoter G-quadruplex. These compounds downregulate c-Myc expression and induce cell-cycle arrest in the sub-G1/G1 phase in cancer cells. They further increase the concentration of intracellular reactive oxygen species. NMR spectra show that three of the newly synthesized compounds interact with the terminal G-quartets (5'- and 3'-ends) in a 2 : 1 stoichiometry.