Search results for "Anti-Bacterial Agents"
showing 10 items of 661 documents
Azacoccones F-H, new flavipin-derived alkaloids from an endophytic fungus Epicoccum nigrum MK214079.
2020
Abstract Three new flavipin-derived alkaloids, azacoccones F-H (1–3), along with six known compounds (4–9) were isolated from the endophytic fungus Epicoccum nigrum MK214079 associated with leaves of Salix sp. The structures of the new compounds were established by analysis of their 1D/2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS) data. The absolute configuration of azacoccones F-H (1–3) was determined by comparison of experimental electronic circular dichroism (ECD) data with reported ones and biogenetic considerations. Epicocconigrone A (4), epipyrone A (5), and epicoccolide B (6) exhibited moderate antibacterial activity again…
Size-exclusion high-performance liquid chromatography in the study of the autoassociating antibiotic gramicidin A in micellar milieu.
2003
Gramicidin A (gA) is a polypeptide antibiotic which forms dimeric channels specific for monovalent cations in biological membranes. It is a polymorphic molecule that adopts several different conformations, double-stranded (ds) helical dimers (pore conformation) and single-stranded beta-helical dimers (channel conformation). This study investigated the conformational adaptability of gramicidin A when incorporated into micelles as membrane-mimetic model system. Taking advantage of our reported, versatile, size-exclusion high-performance liquid chromatography (SE-HPLC) strategy that allows the separation of double-stranded dimers and monomers, we have quantitatively characterized the conformat…
Lemon Oils Attenuate the Pathogenicity of Pseudomonas aeruginosa by Quorum Sensing Inhibition
2021
The chemical composition of three Citrus limon oils: lemon essential oil (LEO), lemon terpenes (LT) and lemon essence (LE), and their influence in the virulence factors production and motility (swarming and swimming) of two Pseudomonas aeruginosa strains (ATCC 27853 and a multidrug-resistant HT5) were investigated. The main compound, limonene, was also tested in biological assays. Eighty-four compounds, accounting for a relative peak area of 99.23%, 98.58% and 99.64%, were identified by GC/MS. Limonene (59–60%), γ-terpinene (10–11%) and β-pinene (7–15%) were the main compounds. All lemon oils inhibited specific biofilm production and bacterial metabolic activities into biofilm in a dose-dep…
Superior Antibacterial Activity of Integral Lemon Pectin Extracted via Hydrodynamic Cavitation
2020
Abstract Pectin extracted via hydrodynamic cavitation in water only from waste lemon peel and further isolated via freeze drying displays significant antibacterial activity against Staphylococcus aureus, a Gram positive pathogen which easily contaminates food. The antibacterial effect of the new IntegroPectin is largely superior to that of commercial citrus pectin, opening the way to advanced applications of a new bioproduct now obtainable in large amounts and at low cost from citrus juice industry's waste.
The application of phospholipid removal columns and ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry for quantificati…
2016
In this study a robust and sensitive method based on a proposed sample purification procedure, using zirconia-coated Phree™ columns and analysis by ultra-high performance liquid chromatography with triple quadrupole tandem mass spectrometry are presented for the assessment of multi-class antibiotics in farmed fish species. The sample preparation procedure benefited from combined precipitation of proteins and selective removal of phospholipids by Phree™ columns, resulting in a high sensitivity of the method (LOQ 0.3-9mgkg(-1)). The in-house validation results (precision, repeatability, decision limit CCα, detection capability CCβ, etc.) indicate that the elaborated method is fully suitable f…
The Mucus of Actinia equina (Anthozoa, Cnidaria): An Unexplored Resource for Potential Applicative Purposes
2015
The mucus produced by many marine organisms is a complex mixture of proteins and polysaccharides forming a weak watery gel. It is essential for vital processes including locomotion, navigation, structural support, heterotrophic feeding and defence against a multitude of environmental stresses, predators, parasites, and pathogens. In the present study we focused on mucus produced by a benthic cnidarian, the sea anemone Actinia equina (Linnaeus, 1758) for preventing burial by excess sedimentation and for protection. We investigated some of the physico-chemical properties of this matrix such as viscosity, osmolarity, electrical conductivity, protein, carbohydrate, and total lipid contents. Som…
Synergistic effect of recombinant CD4-immunoglobulin in combination with azidothymidine, dideoxyinosine and 0.5 beta-monoclonal antibody on human imm…
1994
Data are presented which indicate that combinations of rCD4 immunoglobulin with azidothymidine, dideoxyinosine or 0.5 beta mouse monoclonal antibodies directed against the V3 region of HIV-1, were more effective in treatment of acute HIV infection in vitro than each compound alone. It is suggested that combination therapy with these compounds is more beneficial in treatment of HIV-infected patients than monotherapy, especially with respect to a reduction of the known side effects and the formation of resistant HIV strains after treatment with nucleoside analogues.
Zn(II)-alloferon complexes - Similar sequence, different coordination modes, no antibacterial activity.
2020
Often, in the search for a highly defined scientific phenomenon, a different one becomes apparent. This was also the case of this work, in the scope of which we planned to search for metal-enhanced, novel antibacterial/ antifungal compounds. Instead, we denied the existence of such and revealed the details of the bioinorganic chemistry of Zn(II)-alloferon complexes. Zinc(II) complexes of alloferon 1 and 2, ligands with a sequential difference of one amino acid only, show a substantially different coordination pattern at physiological pH. In the case of Zn(II)-alloferon 1 species, a histamine-like binding mode is observed (N-terminal amine and imidazole of His-1) and the coordination sphere …
Identification of Gip as a novel phage‐encoded gyrase inhibitor protein of Corynebacterium glutamicum
2021
By targeting key regulatory hubs of their host, bacteriophages represent a powerful source for the identification of novel antimicrobial proteins. Here, a screening of small cytoplasmic proteins encoded by the CGP3 prophage of Corynebacterium glutamicum resulted in the identification of the gyrase-inhibiting protein Cg1978, termed Gip. Pull-down assays and surface plasmon resonance revealed a direct interaction of Gip with the gyrase subunit A (GyrA). The inhibitory activity of Gip was shown to be specific to the DNA gyrase of its bacterial host C. glutamicum. Overproduction of Gip in C. glutamicum resulted in a severe growth defect as well as an induction of the SOS response. Furthermore, …
Mechanisms of quinolone resistance in Aeromonas species isolated from humans, water and eels.
2009
Mechanisms of resistance were determined in 33 quinolone-resistant isolates of the species Aeromonas hydrophila, Aeromonas caviae, Aeromonas media, Aeromonas salmonicida, Aeromonas popoffii and Aeromonas veronii, recovered from humans, freshwater and eels. The quinolone resistance-determining regions (QRDRs) of gyrA and parC genes were sequenced in these resistant strains, as well as in 8 quinolone-sensitive Aeromonas used as controls. All quinolone-resistant Aeromonas carried point mutations in the gyrA QRDR at codon 83, respectively giving rise to substitutions Ser(83)-->Ile (32 strains) or Ser(83)-->Val (1 strain). Almost half of these isolates (48%) carried additional point mutations in…