Structure and genetics of the O-antigen of Enterobacter cloacae K7 containing di-N-acetylpseudaminic acid

The O-antigen (O-polysaccharide) is an essential component of lipopolysaccharide on the surface of Gram-negative bacteria and plays an important role in interaction with host organisms. In this study, we investigated the chemical structure and characterized the gene cluster of Enterobacter cloacae K7 O-antigen. As judged by sugar analyses along with NMR spectroscopy data, E. cloacae K7 antigen has a tetrasaccharide O-unit with the following structure: →8)-β-Psep5Ac7Ac-(2 → 2)-β-L-Rhap-(1 → 4)-α-L-Rhap-(1 → 3)-α-D-Galp-(1→ The O-antigen gene cluster of E. cloacae K7 between conserved genes galF and gnd was sequenced. Most genes necessary for the O-antigen synthesis were found in the cluster and their functions were tentatively assigned by comparison with sequences in the available databases

Unsymmetrical trifluoromethyl methoxyphenyl β-diketones: Effect of the position of methoxy group and coordination at cu(ii) on biological activity

Copper(II) complexes with 1,1,1-trifluoro-4-(4-methoxyphenyl)butan-2,4-dione (HL1) were synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single crystal X-ray diffraction. The biological properties of HL1 and cis-[Cu(L1)2 (DMSO)] (3) were examined against Gram-positive and Gram-negative bacteria and opportunistic unicellular fungi. The cytotoxicity was estimated towards the HeLa and Vero cell lines. Complex 3 demonstrated antibacterial activity towards S. aureus comparable to that of streptomycin, lower antifungal activity than the ligand HL1 and moderate cytotoxicity. The bioactivity was compared with the activity of compounds of similar structures. The effect of changing the position of the methoxy group at the aromatic ring in the ligand moiety of the complexes on their antimicrobial and cytotoxic activity was explored. We propose that complex 3 has lower bioavailability and reduced bioactivity than expected due to strong intermolecular contacts. In addition, molecular docking studies provided theoretical information on the interactions of tested compounds with ribonucleotide reductase subunit R2, as well as the chaperones Hsp70 and Hsp90, which are important biomolecular targets for antitumor and antimicrobial drug search and design. The obtained results revealed that the complexes displayed enhanced affinity over organic ligands. Taken together, the copper(II) complexes with the trifluoromethyl methoxyphenyl-substituted β-diketones could be considered as promising anticancer agents with antibacterial properties. © 2021, MDPI. All rights reserved