Biologically Relevant Macrocyclic Complexes of Copper Spectral, Magnetic, Thermal and Antibacterial Approach

Copper(II) macrocyclic complexes have been synthesized with five novel ligands: L¹-1,7,10,16-tetraaza-2,6,11,15-tetraone-4,13-dithiacycloocta-decane, L²-1,7,11,17-tetraaza-2,6,12,16-tetraone-4,14-dithia-cyclocosane, L³-1,7,10, 13,19,22-hexaaza-2,6,14,18-tetraone-4,16-dithiacyclo-tetracosane, L⁴-1,7,14,20,tetraaza-2,6,15,19-tetraone-4,17,di- thiatricyclo [22, 4, O^21,26, O^8,13] hexacosa-8,10,12,21,23,25-hexene, L⁵- 1,7,13,19,25,26-hexaaza-2,6,14,18 tetraone-4,16 dithia tricyclo [23, 3, 1, I^8,12] hexacosa [8(26), 10, 12, 20(25), 22, 24] hexane and characterized by elemental analysis, molar conductance, magnetic susceptibility, i.r, u.v.–vis, EPR spectral studies, thermal studies and electrochemical properties. The molar conductance measurements of the complexes in DMSO correspond to 1:2 electrolytes. g-Values are calculated for all of the complexes in the polycrystalline form as well as in DMSO solution. On the basis of i.r, electronic and EPR spectral studies a square planar geometry has been assigned to these complexes. Cyclic voltammograms for all the complexes are similar to quasi-reversible redox processes Cu^IICu^II⇆Cu^IICu^I⇆Cu^ICu^I. The complexes were also evaluated against the growth of bacteria (S. fecalis and E.coli) in vitro. An erratum to this article is available at .     

Facile conversion of lactols to lactones using IBX

Lactols, which are insoluble or only sparingly soluble in most of the organic solvents that are generally employed for oxidation, are converted to lactones using o-iodoxybenzoic acid (IBX) in a facile manner under modified experimental conditions [EtOAc-DMSO (9:1) mixture at reflux] in good to excellent isolated yields (66-91%).     

Deciphering the Potential of Pre and Pro-Vitamin D of Mushrooms against Mpro and PLpro Proteases of COVID-19: An In Silico Approach

Vitamin D’s role in combating the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus causing COVID-19, has been established in unveiling viable inhibitors of COVID-19. The current study investigated the role of pre and pro-vitamin D bioactives from edible mushrooms against Mpro and PLpro proteases of SARS-CoV-2 by computational experiments. The bioactives of mushrooms, specifically ergosterol (provitamin D₂), 7-dehydrocholesterol (provitamin-D₃), 22,23-dihydroergocalciferol (provitamin-D₄), cholecalciferol (vitamin-D₃), and ergocalciferol (vitamin D₂) were screened against Mpro and PLpro. Molecular docking analyses of the generated bioactive protease complexes unravelled the differential docking energies, which ranged from −7.5 kcal/mol to −4.5 kcal/mol. Ergosterol exhibited the lowest binding energy (−7.5 kcal/mol) against Mpro and PLpro (−5.9 kcal/mol). The Molecular Mechanics Poisson–Boltzmann Surface Area (MMPBSA) and MD simulation analyses indicated that the generated complexes were stable, thus affirming the putative binding of the bioactives to viral proteases. Considering the pivotal role of vitamin D bioactives, their direct interactions against SARS-CoV-2 proteases highlight the promising role of bioactives present in mushrooms as potent nutraceuticals against COVID-19.     

Efficient Replication Bypass of Size‐Expanded DNA Base Pairs in Bacterial Cells

Supersize me! Size‐expanded DNA bases (xDNA) are able to encode natural DNA sequences in replication. In vitro experiments with a DNA polymerase show nucleotide incorporation opposite the xDNA bases with correct pairing. In vivo experiments using E. coli show that two xDNA bases (xA and xC, see picture) encode the correct replication partners.

     

Nanoscale ripples in self-assembled lipid tubules

Self-assembled cylindrical tubules of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine (DC(8,9)PC) have been studied by atomic force microscopy in both the height and amplitude modes. Nanoscale ripple structures in the cylindrical lipid tubules are clearly resolved in amplitude mode images. The periodicity of the ripples is found to be 200 +/- 30 nm for tubules with diameters in the range from 200 to 650 nm. The angle of the ripples with respect to the equator of the tubules shows a bimodal distribution with centers at approximately 28 degrees and approximately 5 degrees.     

The preparation of 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides from the condensation‐cyclization of dilithiated β‐ketoesters with methyl 2‐(aminosulfonyl)benzoate or 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide

Several β‐ketoesters were dilithiated with an excess of lithium diisopropylamide, followed by condensation with methyl 2‐(aminosulfonyl)benzoate to give intermediates that were not isolated but cyclized to 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides. In most instances involving the ester‐sulfonamide, a single β‐ketoester tautomer is usually formed after recrystallization from ethanol. The same dilithiated β‐ketoesters generally condense less well with 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide (saccharin) under the same conditions to afford the same products usually in the same or lower yields. The use of N,N,N',N'‐tetramethylethylenediamine during these syntheses has sometimes resulted in improved yields of products.     

Novel copper(II) homobinuclear macrocyclic complexes: cyclic voltammetry, biological properties and spectral studies

A series of five new copper(II) macrocyclic complexes have been synthesized by template condensation. The bonding and stereochemistry of the complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility, IR, UV-visible, EPR spectral studies and electrochemical properties. g-Values are calculated for all of the complexes in polycrystalline form as well as in DMSO solution. The magnetic and spectral data indicate square planar geometry for all the complexes. Cyclic voltammograms for all the complexes are similar and involve two quasi-reversible redox processes. Cu(II)Cu(II)<=>Cu(II)Cu(I)<=>Cu(I)Cu(I). Their biological properties have also been studied. The macrocyclic complexes show more anti-bacterial than controlled one. The anti-bacterial activities of the compounds were tested against Streptococcus fecalis and Escherichia coli with different concentrations.     

Micromorphology of pure and PbI2‐doped CdI2 dendritic single crystals

Undoped and PbI₂‐doped dendritic single crystals were grown by vapour growth technique. The basal surfaces of the as grown crystals were examined by optical and electron microscopy to observe wide variety of growth and defect features. Apart from typical features of dendritic growth, features of overgrowth, slip bands, growth steps and their bunching, etc. were observed. The basal surfaces of the crystals were then etched by controlled condensation of water vapour, after optimizing the etching condition, and the microscopic studies were repeated. Etch pits of hexagonal and triangular shape, both symmetric and asymmetric, and of different density, were observed in the case of undoped and doped crystals, respectively. In some cases, crystallographic hillocks were also observed. The crystals were also examined by X‐ray diffraction for their polytypism and related behaviour. The results are analyzed to elicit information on the correlation of structure, defects and surface features of the crystals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)