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

Background

Six different metal complexes of quercetin (Cu, Zn, Co, Vd, Mo, Ni) were synthesized, purified, and characterized by their physical and spectral (UV, IR) data. They were evaluated for their P-gp (permeability glycoprotein) inhibitory activity by in vitro everted sac method in rats. The apparent permeability of atorvastatin (P-gp substrate) from everted sac of the rat intestine was determined in control, standard (verapamil), and groups treated with quercetin-metal complexes. The drug contents were analyzed by validated RP-HPLC method using a mixture of acetonitrile and water (60:40 v/v) adjusted to pH 2.8 with phosphate buffer as mobile phase.

Results

In vitro studies revealed that the apparent permeability of atorvastatin (P-gp substrate) across the small intestine is much affected by the treatment with Cu/Co/Ni complexes of quercetin. The mean ± SD and apparent permeability of atorvastatin decreased after pre-treatment with these metal complexes.

Conclusions

The quercetin Cu/Co/Ni complexes could inhibit P-gp and increase the atorvastatin absorption. Hence, they could be considered P-gp inhibitors.

Spectroscopic, SOD, anticancer, antimicrobial, molecular docking and DNA binding properties of bioactive VO(IV), Cu(II), Zn(II), Co(II), Mn(II) and Ni(II) complexes obtained from 3-(2-hydroxy-3-methoxybenzylidene)pentane-2,4-dione

Novel macrocyclic Schiff base complexes [[ML]X; where M = Cu(II), Co(II), Ni(II), Zn(II), Mn(II) and VO(IV)^; L = macrocyclic ligand; X = Cl₂ and SO₄^2-] have been synthesized and characterized by microanalytical, ¹H, ¹³C NMR, IR, Mass, UV-Vis, EPR spectral studies, as well as conductivity data. All the complexes exhibit square-planar geometry except vanadium complex. Magnetic susceptibility measurements and high conductance data reveal the monomeric and electrolytic nature of the complexes. Electronic absorption, cyclic voltammetry, viscosity measurements have been carried out on the interaction of the complexes with DNA. The results suggest that the complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA. Using gel electrophoresis experiment in the presence and absence of oxidant (H₂O₂) the nuclease cleavage activity of the complexes has been performed on plasmid DNA. The results demonstrate that most of the complexes have promising superoxide dismutase (SOD)-mimetic activity. The in vitro cytotoxicity of ligand and its complexes has also been evaluated against human breast and colon carcinoma cells. Binding interactions and energies of ligand and its metal complexes [ML]²⁺ (M = VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II)) against the receptors EGFR and HER2 are performed using the Auto dock module. Consequently, it is found that the ligand is strong inhibitor for EGFR and HER2 while [VOL]SO₄ is good inhibitor for EGFR and [ZnL]Cl₂ is moderate inhibitor for HER2. The antimicrobial activity of the ligand and its complexes against bacteria Salmonella typhi, Staphylococcus aureus, Escherichia coli and Bacillus subtilis and fungi Aspergillus niger, Aspergillus flavus, Candida Albicans and Rhizoctonia bataicola. The complexes have higher activities than the macrocyclic free Schiff base. Interaction of [VOL]SO₄ to the binding sites of target protein EGFR (PDB ID: 4HJ0). Research HighlightsMacrocyclic Schiff base and its metal complexes were synthesized.Complexes bind to DNA by intercalation via the aromatic ring of the macrocycle into the base pairs of DNA.Vanadyl complex is a good inhibitor for EGFR.The complexes of copper, zinc and vanadium show efficient antitumor activity.Copper and vanadium complexes have superior antimicrobial activity than the standards.

Synthesis and photophysical properties of pyridyl conjugated triazole appended naphthalenediimide derivatives

Pyridyl substituted triazole appended NDI-derivatives displayed two reduction potentials corresponding to the formation of stable anionic radicals. NDI-PyTzs have promising fluorescence and electrochemical properties.

EGFR, HER2 target based molecular docking analysis, in vitro screening of 2, 4, 5-trisubstituted imidazole derivatives as potential anti-oxidant and cytotoxic agents

In our endeavor towards the development of potent molecules for cancer diseases, we have designed and synthesized a series of 2,4,5-trisubstituted imidazole derivatives (B1-B24) and characterized by using various spectroscopic techniques. All these compounds are further evaluated for their in vitro anti-cancer, anti-oxidant activities and molecular docking studies against EGFR, HER2 protein receptors. The in vitro anti-cancer activity analysis reveals that compounds B11 and B16 were found to be effective scaffolds against the tested human cancer cell lines IMR-32, A549 and HeLa. Particularly, B16 and B11 showed effective cytotoxicity against A549 and IMR-32 with IC₅₀ values of 09.521±0.54μM and 10.294±0.43μM, respectively. Moreover, compounds B17, B18 and B23 showed potent activity towards the anti-oxidant screening with IC₅₀ values of 5.87±1.73μM, 6.29±1.27μM and 4.95±1.81μM, respectively compared to standard ascorbic acid. Molecular docking was performed against the EGFR, HER2 protein receptors to provide more insight into their mechanism of interaction by comparing with standard EGFR, HER2 inhibitors like Gefitinib (EFGR), Lapatanib (EGFR), Afitinib (HER2) and Canertinib (HER2). Compounds B15, B16, B11 and B10 were exhibiting their minimum binding energies. Out of the aforementioned docked molecules, B15 and B16 showed the best binding energies of -11.15kcalmol^-1, -10.70kcalmol^-1 and -10.49kcalmol^-1, -10.12kcalmol^-1 against EGFR and HER2 protein receptors, respectively. The molecular docking results are well corroborated with the in vitro anti-cancer activity finding.