Synthesis, characterization, and pharmacological evaluation of some metal complexes of quercetin as P-gp inhibitors

Molecular dynamics, molecular docking, DFT, and ADMET investigations of the Co(II), Cu(II), and Zn(II) chelating on the antioxidant activity and SARS-CoV-2 main protease inhibition of quercetin

The natural flavonol quercetin (Q) is found in many vegetables, fruits, and beverages, and it is known as a strong antioxidant. Its metal ion chelation may increase its antioxidant activity. The present study aims to explore the Co(II), Cu(II), and Zn(II) chelating on the antioxidant effectiveness and severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) main protease (Mpro) inhibitory of quercetin using Density-functional theory (DFT), molecular docking, and molecular dynamics simulations (MD). DFT calculations at the B3LYP/LanL2DZ reveal that the high antioxidant activity of the metal-chelated quercetin complexes is mainly returned to their lower ionization potentials (IPs) compared with the one of the free quercetin. Molecular docking of quercetin and its Co(II), Cu(II), and Zn(II) chelates into the active binding sites of peroxiredoxin 5 and SARS-CoV-2 main protease (Mpro) were performed using Lamarckian Genetic Algorithm method. The docked quercetin and its metal chelates fit well into the binding site of the target proteins, and their binding affinity is strongly influenced by the type of the chelated metals Co(II), Cu(II), and Zn(II), and molar ratio metal: ligand, i.e. 1:2 and 2:1. Further, the binding stability of QZn2 and QCu2 in peroxiredoxin 5 and SARS-CoV-2 main protease targets is evaluated using MD simulation conducted for 100 ns simulations at natural room temperature conditions, and the obtained results showed that all chelates remain bound to the ligand binding groove of protein except for 1HD2_QZn2 complex. Finally, the adsorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of quercetin and cobalt(II)-quercetin (QCo2(II)) were investigated.Communicated by Ramaswamy H. Sarma.

Synthesis and Characterization of Quercetin-Iron Complex Nanoparticles for Overcoming Drug Resistance

Quercetin, one of the major natural flavonoids, has demonstrated great pharmacological potential as an antioxidant and in overcoming drug resistance. However, its low aqueous solubility and poor stability limit its potential applications. Previous studies suggest that the formation of quercetin-metal complexes could increase quercetin stability and biological activity. In this paper, we systematically investigated the formation of quercetin-iron complex nanoparticles by varying the ligand-to-metal ratios with the goal of increasing the aqueous solubility and stability of quercetin. It was found that quercetin-iron complex nanoparticles could be reproducibly synthesized with several ligand-to-iron ratios at room temperature. The UV-Vis spectra of the nanoparticles indicated that nanoparticle formation greatly increased the stability and solubility of quercetin. Compared to free quercetin, the quercetin-iron complex nanoparticles exhibited enhanced antioxidant activities and elongated effects. Our preliminary cellular evaluation suggests that these nanoparticles had minimal cytotoxicity and could effectively block the efflux pump of cells, indicating their potential for cancer treatment.