Natural RNA dependent RNA polymerase inhibitors: Molecular docking studies of some biologically active alkaloids of Argemone mexicana.

COVID-19 has become disastrous for world and spread all over. Researchers all around the globe are working to discover a drug to cure from COVID-19. RNA dependent RNA polymerase plays a key role in SARS-CoV-2 replication and thus it could be a potential target for SARS-CoV-2. This study revealed that Protopine, Allocryptopine and (±) 6- Acetonyldihydrochelerythrine could be potential RdRp inhibitors of SARS-CoV-2.

Paramagnetic resonance in imidazolate-bridged homobinuclear (copper-copper) and heterobinuclear (copper-zinc) complexes.

Bridged homobinuclear (copper-copper) and heterobinuclear (copper-zinc) complexes of diethylenetriamine have been prepared with 2-methyl-imidazole as bridging ligand. EPR spectra of the polycrystalline complexes have been studied at room temperature and also at liquid nitrogen temperature. Low temperature EPR and electronic spectroscopic studies of 50% aqueous DMSO of [(dien)Cu-(Melm)-Zn(dien)]3+ solutions show the imidazolate bridged complex to exist mainly over the pH range approximately 7.0 < pH < 10.0. At low pH the 2-MelmH+ ion and mononuclear copper and zinc complexes are formed. Above pH > 10.0 hydroxide ion splits the imidazolate bridge.

E.s.r., visible and SOD studies of imidazolate bridged Cu(2)(II,II), Cu(II)Zn(II) and Cu(II)Ni(II) complexes with pentamethyldiethylenetriamine as capping ligand: a plausible model for superoxide dismutase.

X-band e.s.r. and electronic spectra of imidazolate bridged homobinuclear Cu-Cu complex, [(PMDT)Cu-Im-Cu(PMDT)](ClO(4))(3) and heterobinuclear Cu-Zn and Cu-Ni complexes, viz. [(PMDT)Cu-Im-Zn(PMDT)](ClO(4))(3), [(PMDT)Cu-Im-Ni(PMDT)] (ClO(4))(3), where PMDT=pentamethyldiethylenetriamine, Im=Imidazolate ion and related mononuclear complexes, [(PMDT)Cu(OH(2))](2+) and [(PMDT)Cu(ImH)](2+) have been described. Superoxide dismutase activities of these complexes have also been measured.

Paramagnetic resonance and visible spectroscopic properties of binuclear Cu-Cu and Cu-Zn imidazolate-bridged complexes: effective model for active site of superoxide dismutase.

Syntheses of the imidazolate-bridged heterometallic binuclear copper-zinc complex [(glyala)Cu-im Zn(g-lyala)]Na, where H2glyala = glycylalanine, and im = imidazolate ion, has been achieved. X-band e.p.r and visible absorption spectra of the complex [(glyala)Cu-im-Zn(glyala)]Na at different pH values in frozen solution (50% aqueous DMSO, 77K) show that the imidazolate-bridged complex is stable in the pH range 7.15-10.50.

Coordination of copperpolyamine complex with imidazoles potentiates it superoxide dismutase mimicking activity and abolishes its interaction with albumin.

Mixed ligand complexes of copper polyamine with biomolecules such as imidazole, substituted imidazoles or pyridine have been synthesized and characterized. These molecules were used because of their low toxicity and high activity. These complexes were found to possess a distorted octahedral microenvironment with a potential SOD mimicking activity. The IC50 values for these complexes were of the order of 2-90 microM. Pyridine and imidazole complexes were most effective as they possess the lowest IC50 values of 2.1 and 6 microM respectively which are higher than the IC50 value of polyamine copper complex. Based on the uric acid estimations, it has also been ascertained that these complexes dismute O2- without inhibiting xanthine oxidase activity. The presence of increasing concentrations of albumin had no effect on the SOD mimicking activity of mixed ligand complexes. Polyamine complex, however lost approximately 80% of SOD mimicking activity in the presence of albumin (1 mg). These results suggest that coordination of polyamine copper complex with imidazoles/pyridine may abolish their binding affinity for albumin while potentiating their SOD mimicking activity.

X-band electron paramagnetic resonance spectra of bovine serum albumin-copper(II) and bovine serum albumin-copper(II)-aminoacid systems.

X-band electron paramagnetic resonance (epr) spectra of the binary systems, BSA-copper(II) (1:1 and 2:1), and the ternary systems, BSA-Cu(II)-aminoacid (1:1:1), are described. In the binary system, two distinct epr features have been observed. One of the features (towards the low pH), showing broad and overlapping epr signals, has been attributed to non-specific bonding of copper(II) to the albumin and other feature (towards higher pH), showing sharp intense epr signals, has been attributed to the specific bonding. The change from non-specific to specific binding is favoured by increase in pH as well as by increase in protein concentration. Specific binding of copper(II) in BSA-Cu(II) has been suggested to be similar to that in HSA-Cu(II). Spectra of BSA-Cu(II)-aminoacid (1:1:1) show simultaneous presence of binary BSA-Cu(II) and ternary BSA-Cu(II)-aminoacid.

The organic cofactor in plasma amine oxidase: evidence for pyrroloquinoline quinone and against pyridoxal phosphate.

Plasma amine oxidases (EC 1.4.3.6) are classified as containing the organic cofactor pyridoxal phosphate. Biochemical and bioassays on the pig plasma amine oxidase fail to reveal the presence of pyridoxal phosphate and 31P n.m.r. evidence is also inconsistent with pyridoxal phosphate in the enzyme. Resonance Raman spectral studies on phenylhydrazone derivatives of the pig and bovine plasma enzymes have been carried out and comparisons made with the corresponding derivatives of pyridoxal phosphate and pyrroloquinoline quinone (PQQ). The resonance Raman evidence indicates that the cofactor in both plasma amine oxidases is PQQ or a closely related species and not pyridoxal phosphate. The results substantiate earlier reports concerning the identity of the organic cofactor.

Electron nuclear double-resonance (ENDOR) spectroscopy of amine oxidase from pig plasma.

Electron nuclear double-resonance ('ENDOR') spectroscopic studies on pig plasma amine oxidase have been carried out at 15 K. Deuterium-exchange studies show the presence of two sets of exchangeable protons, probably from two water molecules; from the magnitude of their hyperfine couplings, one is assigned to be equatorially, and the other axially, co-ordinated. Only one 14N hyperfine coupling is observed, suggesting that the bonding of all amino acid (histidine) or organic cofactor ligands is similar. Upon addition of azide, a further hyperfine coupling to nitrogen is observed which is smaller than that observed for the native enzyme; the hyperfine couplings to the remaining nitrogens are slightly altered.

Polarographic behaviour of some o-hydroxyketoximes.

The polarographic behaviour of three o-hydroxyketoximes, CH(3)C(6)H(3)(OH)CRNOH, where R CH(3), C(2)H(5) and C(3)H(7), has been studied in 5% ethanolic medium, with potassium chloride as supporting electrolyte. A single four-electron reduction wave is obtained which diminishes with increase in pH, being replaced by a new wave in alkaline media. A trough is formed on the limiting-current plateau at higher negative potentials. A mechanism has been proposed for the reduction at the dropping mercury electrode.