scholarly journals Mersaquinone, A New Tetracene Derivative from the Marine-Derived Streptomyces sp. EG1 Exhibiting Activity against Methicillin-Resistant Staphylococcus aureus (MRSA)

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 252 ◽  
Author(s):  
Min Cheol Kim ◽  
Reiko Cullum ◽  
Ali M. S. Hebishy ◽  
Hala A. Mohamed ◽  
Ahmed H. I. Faraag ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
2D Nmr ◽  
North Coast ◽  
Spectroscopic Techniques ◽  
Methicillin Resistant ◽  
Streptomyces Sp ◽  
The North ◽  
Societal Challenges ◽  
New Antibiotics

New antibiotics are desperately needed to overcome the societal challenges being encountered with methicillin-resistant Staphylococcus aureus (MRSA). In this study, a new tetracene derivative, named Mersaquinone (1), and the known Tetracenomycin D (2), Resistoflavin (3) and Resistomycin (4) have been isolated from the organic extract of the marine Streptomyces sp. EG1. The strain was isolated from a sediment sample collected from the North Coast of the Mediterranean Sea of Egypt. The chemical structure of Mersaquinone (1) was assigned based upon data from a diversity of spectroscopic techniques including HRESIMS, IR, 1D and 2D NMR measurements. Mersaquinone (1) showed antibacterial activity against methicillin-resistant Staphylococcus aureus with a minimum inhibitory concentration of 3.36 μg/mL.

scholarly journals Isoflavonoids from an Egyptian Collection of Colutea Istria

2008 ◽  
Vol 3 (9) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Mohamed M. Radwan
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
2D Nmr ◽  
Cytotoxic Activities ◽  
Spectroscopic Techniques ◽  
Methicillin Resistant ◽  
Aerial Parts ◽  
Selective Antimicrobial Activity

Two new isoflavonoids have been isolated from the aerial parts of Colutea istria Lam. of Egyptian origin and identified as (3 R)-7-hydroxy-3′,4′-dimethoxyisoflavan-2′,5′-quinone (1) and 6,3′-dihydroxy-7,4′-dimethoxyisoflavone (2). Their structures were determined by various 1D and 2D NMR spectroscopic techniques. The antibacterial, antifungal, antimalarial and cytotoxic activities of 1 and 2 were evaluated. Compound 1 displayed selective antimicrobial activity against Methicillin-resistant Staphylococcus aureus with an IC50 value of 20 μg/mL.

scholarly journals Evolutionary GEM: The Evolution of Methicillin-resistant Staphylococcus aureus

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Jaiden Tu ◽  
Patricia M. Gray
Keyword(s):  
Public Health ◽  
Staphylococcus Aureus ◽  
Horizontal Gene Transfer ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Rapid Evolution ◽  
Public Health Issue ◽  
Major Public Health Issue ◽  
Methicillin Resistant ◽  
Gene Variation ◽  
New Antibiotics

Since 1961, methicillin-resistant Staphylococcus aureus (MRSA) has evolved through both single locus gene variation and horizontal gene transfer. By the late 1970s, the emergence of new SCCmec allotypes marked the beginning of a worldwide MRSA pandemic. The continuous and rapid evolution of MRSA, in response to new antibiotics, remains a major public health issue worldwide.

scholarly journals Synthesis of Antibacterial Nisin-Peptoid Hybrids Using Click Methodology

2018 ◽  
Author(s):  
Hannah L. Bolt ◽  
Laurens H.J. Kleijn ◽  
Nathaniel I. Martin ◽  
Steven L. Cobb
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Peptides ◽  
Antibacterial Agents ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Methicillin Resistant ◽  
Lipid Ii ◽  
New Antibiotics

Antimicrobial peptides and structurally related peptoids offer potential for the development of new antibiotics. However, progress has been hindered by challenges presented by poor in vivo stability (peptides) or lack of selectivity (peptoids). Herein, we have developed a process to prepare novel hybrid antibacterial agents that combine both linear peptoids (increased in vivo stability compared to peptides) and a nisin fragment (lipid II targeting domain). The hybrid nisin-peptoids prepared were shown to have low µM activity (comparable to natural nisin) against methicillin-resistant Staphylococcus aureus.

Antibacterial and synergic effects of gallic acid-grafted-chitosan with β-lactams against methicillin-resistant Staphylococcus aureus (MRSA)

2014 ◽  
Vol 60 (10) ◽  
pp. 629-638 ◽  
Author(s):  
Dae-Sung Lee ◽  
Sung-Hwan Eom ◽  
Young-Mog Kim ◽  
Hye Seon Kim ◽  
Mi-Jin Yim ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Gallic Acid ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Synergistic Effects ◽  
Cell Envelope ◽  
Bactericidal Effect ◽  
Clinical Isolates ◽  
Methicillin Resistant ◽  
New Antibiotics ◽  
Time Kill

Methicillin-resistant Staphylococcus aureus (MRSA) is spreading worldwide, emphasizing the need to search for new antibiotics. The anti-MRSA activities of gallic acid-grafted-chitosans (GA-g-chitosans) were investigated against 2 MRSA standards and 10 MRSA clinical isolates by determining the minimum inhibitory concentrations (MICs). GA-g-chitosan (I), which has the highest gallic acid content, exhibited the strongest anti-MRSA activities, with MICs of 32–64 μg/mL. A time-kill investigation revealed that GA-g-chitosan (I) exhibited a bactericidal effect at twice the MIC, also demonstrating good thermal and pH stability. Investigation of cell envelope integrity showed the release of intracellular components with an increasing absorbance value at 260 nm, indicating cell envelope damage caused by the GA-g-chitosan (I), which was further confirmed by transmission electron microscopy. When GA-g-chitosans were combined with β-lactams, including ampicillin and penicillin, synergistic effects were observed on the 2 standard MRSA strains and on the 10 clinical isolates, with fractional inhibitory indices ranging from 0.125 to 0.625. In the time-kill dynamic confirmation test, synergistic bactericidal effects were observed for the combinations of GA-g-chitosans with β-lactams, and over 4.0 log CFU/mL reductions were observed after 24 h when combination treatment was used. These results may prove GA-g-chitosans to be a potent agent when combined with ampicillin and penicillin for the elimination of MRSA.

scholarly journals Dihydrostilbenes from Indigofera Pulchra

2008 ◽  
Vol 3 (5) ◽  
pp. 1934578X0800300
Author(s):  
Aliyu Musa ◽  
A. K. Haruna ◽  
M. Ilyas ◽  
Augustine Ahmadu ◽  
Simon Gibbons ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Nmr Spectroscopy ◽  
Structure Elucidation ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Efflux Pump ◽  
2D Nmr ◽  
Multidrug Resistant ◽  
Methicillin Resistant ◽  
Weak Activity

A mixture of two new dihydrostilbenes, 3-methoxy-4,5-methylenedioxy-4′- O-(2ξ,3-dihydroxy-3-methylbutyl)-dihydrostilbene (1) and 3,5-dimethoxy-4′- O-(2ξ,3-dihydroxy-3-methylbutyl)-dihydrostilbene (2), was isolated from Indigofera pulchra as an inseparable mixture. Several isolation strategies, including multiple preparative TLC, SPE and finally HPLC were undertaken in an attempt to separate these metabolites, but to no avail. Structure elucidation on the mixture was conducted and we were able to establish the structures of these compounds unambiguously by MS and a series of 1D and 2D-NMR analyses. The mixture of these dihydrostilbenes was analyzed by NMR spectroscopy and 1 and 2 were in a ratio of 52:48, respectively, and this was evaluated against a panel of methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant variants of this organism, including a strain over-expressing the NorA efflux pump; weak activity was observed.

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