Synthesis, Characterization and DNA-Binding Affinity of a New Zinc(II) Bis(5-methoxy-indol-3-yl)propane-1,3-dione Complex

Abstract

The novel zinc(II) µ-oxo-bridged-dimeric complex [Zn2(µ-O)2(BMIP)2] (BMIP = 1,3-bis(5-methoxy-1-methyl-1H-indol-3-yl)propane-1,3-dione), 1, was synthetized and fully characterized. The spectral data indicate a zincoxane molecular structure, with the BMIP ligand coordinating in its neutral form via its oxygen atoms. Structural changes in 1 in dimethylsulfoxide (DMSO) were evidenced by means of spectroscopic techniques including infrared absorption and nuclear magnetic resonance, showing DMSO entrance in the coordination sphere of the metal ion. The resulting complex [Zn2(µ-O)2(BMIP)2(DMSO)], 2, readily reacts in the presence of N-methyl-imidazole (NMI), a liquid-phase nucleoside mimic, to form [Zn2(µ-O)2(BMIP)2(NMI)], 3, through DMSO displacement. The three complexes show high thermal stability, demonstrating that 1 has high affinity for hard nucleophiles. Finally, with the aim of probing the suitability of this system as model scaffold for new potential anticancer metallodrugs, the interactions of 1 with calf thymus DNA were investigated in vitro in pseudo-physiological environment through UV-Vis absorption and fluorescence emission spectroscopy, as well as time-resolved fluorescence studies. The latter analyses revealed that [Zn2(µ-O)2(BMIP)2(DMSO)] binds to DNA with high affinity upon DMSO displacement, opening new perspectives for the development of optimized drug substances.

New Xanthone Derivatives as Potent G-Quadruplex Binders for Developing Anti-Cancer Therapeutics

“…UV–vis experiments are well established for assessing DNA–drug interactions. − There are many previous reports where this method has been used to screen small molecules to check their capabilities of nucleic acid binding. − ,,, The large π-surface of the xanthone core provides an opportunity to perform UV–vis titration where the changes (hypochromism, spectral band maximum shifts, etc.) noticed in the absorption band of the compound upon addition of various DNA forms can be followed and the resulting observations can be compared to discern the nature of the ligand–DNA interactions.…”

Asymmetric Phenyl Substitution: An Effective Strategy to Enhance the Photosensitizing Potential of Curcuminoids

“…The absorption spectrum consists of a single broad band peaking at around 420 nm, with a shoulder at longer wavelengths. This suggests, by comparison with 1 as well as other curcuminoids and β-diketones [36][37][38][39][40][41][42][43][44]52], that the keto-enol equilibrium is notably shifted towards the enol tautomers, with the diketo tautomers appearing at most in traces. The NMR spectroscopy and in silico calculations support the above conclusion (vide infra).…”

Synthesis, Characterization, Fluorescence Properties, and DFT Modeling of Difluoroboron Biindolediketonates

“…We recently reported on the chemistry of indoles [ 15 , 16 ] and the use of biindole diketones (bdks) as ligands in the synthesis and characterization of biindole diketone coordination complexes [ 17 ]. Metalloorganic complexes of these bdks have been proposed as possible next-generation chemotherapeutic drugs to replace cis-platinum derivatives [ 17 ].…”

“…We recently reported on the chemistry of indoles [ 15 , 16 ] and the use of biindole diketones (bdks) as ligands in the synthesis and characterization of biindole diketone coordination complexes [ 17 ]. Metalloorganic complexes of these bdks have been proposed as possible next-generation chemotherapeutic drugs to replace cis-platinum derivatives [ 17 ]. In this work, we present synthesis and spectroscopic characterization studies of BF 2 bdks having 5,5′-disubstituted 3,3′-biindole-1,3-propanedione (BIP) ligands (see Scheme 1 ).…”