scholarly journals Improved Derivatives of Bactenecin, a Cyclic Dodecameric Antimicrobial Cationic Peptide

1999 ◽  
Vol 43 (5) ◽  
pp. 1274-1276 ◽  
Author(s):  
Manhong Wu ◽  
Robert E. W. Hancock
Keyword(s):  
Amino Acid ◽  
Antimicrobial Peptide ◽  
Tryptophan Residue ◽  
Gram Negative Bacteria ◽  
Cationic Peptide ◽  
Gram Positive ◽  
Antimicrobial Spectrum ◽  
Gram Negative ◽  
Derivatives Of

ABSTRACT Both linear and cyclic derivatives of the cyclic 12-amino-acid antimicrobial peptide bactenecin were designed based on optimization of amphipathicity and charge location. In general, increasing the number of positive charges at the N and C termini and adding an extra tryptophan residue in the loop not only increased the activities against both gram-positive and gram-negative bacteria but also broadened the antimicrobial spectrum.

Structure-Activity Relationship and Antimicrobial Evaluation of N-Phenylpyrazole Curcumin Derivatives

2020 ◽  
Vol 16 (4) ◽  
pp. 481-488
Author(s):  
Heli Sanghvi ◽  
Satyendra Mishra
Keyword(s):  
Antibacterial Activity ◽  
Gram Negative Bacteria ◽  
Pyrazole Derivatives ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Curcumin Derivatives ◽  
Structure Activity ◽  
Electron Donating Groups ◽  
Derivatives Of

Background: Curcumin, one of the most important pharmacologically significant natural products, has gained significant consideration among scientists for decades since its multipharmacological activities. 1, 3-Dicarbonyl moiety of curcumin was found to be accountable for the rapid degradation of curcumin molecule. The aim of present work is to replace 1, 3-dicarbonyl moiety of curcumin by pyrazole and phenylpyrazole derivatives with a view to improving its stability and to investigate the role of substitution in N-phenylpyrazole curcumin on its antibacterial activity against both Gram-positive as well as Gram-negative bacteria. Methods: Pyrazole derivatives of curcumin were prepared by heating curcumin with phenyhydrazine/ substituted phenyhydrazine derivatives in AcOH. The residue was purified by silica gel column chromatography. Structures of purified compounds were confirmed by 1H NMR and Mass spectroscopy. The synthesized compounds were evaluated for their antibacterial activity by the microdilution broth susceptibility test method against gram positive (S. aureus) and gram negative (E. coli). Results: Effects of substitution in N-phenylpyrazole curcumin derivatives against S. aureus and E. coli were studied. The most active N-(3-Nitrophenylpyrazole) curcumin (12) exhibits twenty-fold more potency against S. aureus (MIC: 10μg/mL)) and N-(2-Fluoroophenylpyrazole) curcumin (5) fivefold more potency against E. coli (MIC; 50 μg/mL) than N-phenylpyrazole curcumin (4). Whereas, a remarkable decline in anti-bacterial activity against S. aureus and E. coli was observed when electron donating groups were incorporated in N-phenylpyrazole curcumin (4). Comparative studies of synthesized compounds suggest the effects of electron withdrawing and electron donating groups on unsubstituted phenylpyrazole curcumin (4). Conclusion: The structure-activity relationship (SAR) results indicated that the electron withdrawing and electron donating at N-phenylpyrazole curcumin played key roles for their bacterial inhibitory effects. The results of the antibacterial evaluation showed that the synthesized pyrazole derivatives of curcumin displayed moderate to very high activity in S. aureus. In conclusion, the series of novel curcumin derivatives were designed, synthesized and tested for their antibacterial activities against S. aureus and E. coli. Among them, N-(3-Nitrophenylpyrazole curcumin; 12) was most active against S. aureus (Gram-positive) and N-(2-Fluoroophenylpyrazole) curcumin (5) against E. coli (Gram-negative) bacteria.

scholarly journals Synthesis and Evaluation of Antimicrobial Activity of Nitrones from Derivatives of Aryl-Substituted Dihydroisoquinoline

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Mouna Bouzid ◽  
Raed Abdennabi ◽  
Mohamed Damak ◽  
Majed Kammoun
Keyword(s):  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
High Purity ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Derivatives Of

This paper describes the synthesis of a series of dihydroisoquinoline nitrones by isomerization of the corresponding oxaziridines. Nitrones4a–cwere obtained in excellent yields and high purity by a simple and effective method from the isomerization of oxaziridines. The synthesized compounds were also evaluated for their antibacterial activity against Gram-positive and Gram-negative bacteria and fungus.

scholarly journals Properties of β-lactamases produced by three species of mycobacteria

1968 ◽  
Vol 107 (5) ◽  
pp. 675-682 ◽  
Author(s):  
J. E. Kasik ◽  
Lin Peacham
Keyword(s):  
Mycobacterium Smegmatis ◽  
Extracellular Fluid ◽  
Gram Negative Bacteria ◽  
Cephalosporin C ◽  
Gram Positive ◽  
Intact Cells ◽  
Gram Negative ◽  
Substrate Specificities ◽  
High Concentrations ◽  
Derivatives Of

1. Mycobacterium smegmatis (N.C.T.C. 8158), M. fortuitum and M. phlei (MPI) produce a constitutive β-lactamase that has penicillinase and cephalosporinase activity. 2. The β-lactamases of these three species of acid-fast bacteria were mainly cell-bound, only small amounts of activity being liberated into the extracellular fluid. The total β-lactamase activity of these mycobacteria was much lower than that of certain Gram-positive organisms, but comparable with that reported for species of Gram-negative bacteria. 3. The β-lactamases of intact cells of the mycobacteria were not freely accessible to any of the substrates tested, but the apparent crypticity factor to benzylpenicillin was greater than that to cephaloridine and cephalosporin C. 4. Attempts to induce β-lactamase activity in M. smegmatis and M. phlei failed even with high concentrations of inducer. 5. The β-lactamases obtained from the three species of mycobacteria showed different substrate specificities, including different relative activities as cephalosporinases and penicillinases respectively. 6. Certain derivatives of 6-aminopenicillanic acid and 7-aminocephalosporanic acid were found to be resistant to hydrolysis by β-lactamases of M. smegmatis and M. fortuitum. 7. The β-lactamase of M. smegmatis was competitively inhibited by a number of β-lactamase-resistant derivatives of 6-aminopenicillanic acid, but not by similar derivatives of 7-aminocephalosporanic acid.

scholarly journals Nanocomposites with ornidazole—antibacterial and antiadhesive agents against Gram-positive and Gram-negative bacteria

2020 ◽  
Vol 10 (8) ◽  
pp. 3193-3203
Author(s):  
I. Furtat ◽  
M. Lupatsii ◽  
T. Murlanova ◽  
P. Vakuliuk ◽  
A. Gaidai ◽  
...  
Keyword(s):  
Bacterial Adhesion ◽  
Therapeutic Potential ◽  
Antimicrobial Properties ◽  
Bactericidal Effect ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Antimicrobial Spectrum ◽  
Gram Negative ◽  
Index Index ◽  
Adhesion Index

AbstractAntimicrobial resistance of many microbial species can cause to thousands of deaths worldwide, in this regard new therapeutic strategies have to be invented. To address the question, we have prepared nanocomposites on the basis of pyrogenic silicon dioxide with ornidazole immobilized on the surface (ornidasil) and studied their antimicrobial properties and the therapeutic potential. It has also been shown, that in comparison with pure ornidazole the addition of ornidazole to nanocomposite composition can enhance the antimicrobial spectrum, including Gram-positive and Gram-negative bacteria. The most significant bactericidal effect has been reached after more than 24-h treatment with the nanocomposite. Antiadhesive properties of nanocomposite materials were studied using blood types OO+, AO+, BO+, AB+, the degree of bacterial adhesion was estimated using three indexes: average adhesion index, index of erythrocytes involvement, index of microbial adhesion. The effectiveness of the treatment with the nanocomposites obtained was studied on complicated wounds of various etiologies, in particular the wounds caused by diabetic foot syndrome.

scholarly journals Synthesis and Biologically Important of 2-Mercaptobenthiazole (MBT)-Clubbed Chalcone Derivatives

2016 ◽  
Vol 63 ◽  
pp. 83-89
Author(s):  
Falguni Bhabhor ◽  
K. Satish ◽  
Hiren Variya ◽  
Vikram Panchal
Keyword(s):  
Elemental Analysis ◽  
Antimicrobial Properties ◽  
Spectral Characterization ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Chalcone Derivatives ◽  
H Nmr ◽  
Derivatives Of

In this present work base catalyzed method used for formation of Chalcone of (E)-4-(3-(4-hydroxyphenyl) acryloyl)-5-methyl-2(p-tolyl)-1H-pyrazol-3(2H)-one (II) reacted with derivatives of S-benzo [d] thiol-2yl-2-chloroethanethioate (Ia-f) resulted in formation of corresponding derivatives of (E)-S-benzo [d] thiazol-2-yl 2-(4-(3-(5-methyl-3oxo-2(p-tolyl)-2,3-dihydro-1H-pyrazol-4-yl)-3-oxoprop-1-en-1-yl) phenoxy) etanethioate (IIIa-f) was confirmed by spectral characterization such as IR,1H NMR, LC-MS and elemental analysis. The compounds were screened for their antimicrobial properties against a broad panel Gram-positive and Gram-negative bacteria as well as fungi.

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