scholarly journals Secondary Structural Preferences of Some Antibacterial Cyclooctapeptides in the Presence of Calcium(II)

2012 ◽  
Vol 2012 ◽  
pp. 1-10
Author(s):  
Tarshona Stevens ◽  
Nykia McNeil ◽  
Xiuli Lin ◽  
Maria Ngu-Schwemlein
Keyword(s):  
Antibacterial Activity ◽  
Absorption Band ◽  
Titration Calorimetry ◽  
Conformational Structure ◽  
Binding Affinities ◽  
Beta Sheet ◽  
Antibacterial Compounds ◽  
Weak Binding ◽  
Beta Sheet Structure ◽  
Structural Preferences

The purpose of this study is to understand the interactions of some antibacterial cationic amphipathic cyclooctapeptides with calcium(II) and their secondary structural preferences. The thermodynamic parameters associated with calcium(II) interactions, between the antibacterial active cyclooctapeptides (COP 1–6) and those that did not exhibit significant activities (COP 7–9), were studied by isothermal titration calorimetry. Calcium(II) binding in the absence and presence of micellar dodecylphosphocholine (DPC), a membrane mimicking detergent, was conducted by circular dichroism (CD). Both groups of cyclopeptides showed weak binding affinities for calcium(II) (Kb ca. 10−3 M−1). However, CD data showed that the antimicrobial peptides COP 1–6 adopted a twisted beta-sheet structure (positive CD absorption band at ca. 203 nm) in the presence of calcium(II) in micellar DPC. In contrast, COP 7–9, which lacked antibacterial activity, adopted a different conformational structure (negative CD absorption band at ca. 203 nm). These results indicate that these cyclopeptides could adopt secondary structural preferences in the presence of calcium(II) amidst a hydrophobic environment to elicit their antibacterial activity. These findings could be useful in facilitating the design of cyclopeptide derivatives that can adopt this beta-sheet-like secondary structure and, thereby, provide a useful molecular template for crafting antibacterial compounds.

scholarly journals Antibacterial Activity of Fluorobenzoylthiosemicarbazides and Their Cyclic Analogues with 1,2,4-Triazole Scaffold

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 170
Author(s):  
Urszula Kosikowska ◽  
Monika Wujec ◽  
Nazar Trotsko ◽  
Wojciech Płonka ◽  
Piotr Paneth ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Resistant Bacteria ◽  
Binding Affinities ◽  
Substitution Pattern ◽  
Minimal Inhibitory Concentrations ◽  
Gram Positive Bacteria ◽  
Structure Activity ◽  
Drug Resistant Bacteria ◽  
Reference Strains

The development of drug-resistant bacteria is currently one of the major challenges in medicine. Therefore, the discovery of novel lead structures for the design of antibacterial drugs is urgently needed. In this structure–activity relationship study, a library of ortho-, meta-, and para-fluorobenzoylthiosemicarbazides, and their cyclic analogues with 1,2,4-triazole scaffold, was created and tested for antibacterial activity against Gram-positive bacteria strains. While all tested 1,2,4-triazoles were devoid of potent activity, the antibacterial response of the thiosemicarbazides was highly dependent on substitution pattern at the N4 aryl position. The optimum activity for these compounds was found for trifluoromethyl derivatives such as 15a, 15b, and 16b, which were active against both the reference strains panel, and pathogenic methicillin-sensitive and methicillin-resistant Staphylococcus aureus clinical isolates at minimal inhibitory concentrations (MICs) ranging from 7.82 to 31.25 μg/mL. Based on the binding affinities obtained from docking, the conclusion can be reached that fluorobenzoylthiosemicarbazides can be considered as potential allosteric d-alanyl-d-alanine ligase inhibitors.

scholarly journals Modulatory Effects of Caffeine and Pentoxifylline on Aromatic Antibiotics: A Role for Hetero-Complex Formation

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3628
Author(s):  
Anna Woziwodzka ◽  
Marta Krychowiak-Maśnicka ◽  
Grzegorz Gołuński ◽  
Anna Felberg ◽  
Agnieszka Borowik ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Drug Repurposing ◽  
Activity Level ◽  
Titration Calorimetry ◽  
Human Pathogens ◽  
Neighborhood Association ◽  
Treatment Regimens ◽  
Vis Spectroscopy ◽  
Antibiotic Interactions

Antimicrobial resistance is a major healthcare threat globally. Xanthines, including caffeine and pentoxifylline, are attractive candidates for drug repurposing, given their well-established safety and pharmacological profiles. This study aimed to analyze potential interactions between xanthines and aromatic antibiotics (i.e., tetracycline and ciprofloxacin), and their impact on antibiotic antibacterial activity. UV-vis spectroscopy, statistical-thermodynamical modeling, and isothermal titration calorimetry were used to quantitatively evaluate xanthine-antibiotic interactions. The antibacterial profiles of xanthines, and xanthine-antibiotic mixtures, towards important human pathogens Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, and Enterobacter cloacae were examined. Caffeine and pentoxifylline directly interact with ciprofloxacin and tetracycline, with neighborhood association constant values of 15.8–45.6 M−1 and enthalpy change values up to −4 kJ·M−1. Caffeine, used in mixtures with tested antibiotics, enhanced their antibacterial activity in most pathogens tested. However, antagonistic effects of caffeine were also observed, but only with ciprofloxacin toward Gram-positive pathogens. Xanthines interact with aromatic antibiotics at the molecular and in vitro antibacterial activity level. Given considerable exposure to caffeine and pentoxifylline, these interactions might be relevant for the effectiveness of antibacterial pharmacotherapy, and may help to identify optimal treatment regimens in the era of multidrug resistance.

Serial Extraction Technique of Rich Antibacterial Compounds in Sargassum cristaefolium Using Different Solvents and Testing their Activity

2021 ◽  
Vol 17 ◽  
Author(s):  
Bambang Susilo ◽  
Abd. Rohim ◽  
Midia Lestari W. H.
Keyword(s):  
Antibacterial Activity ◽  
Brown Seaweed ◽  
Inhibition Zone ◽  
Extraction Yield ◽  
Single Step ◽  
Extraction Technique ◽  
Cinnamic Aldehyde ◽  
Antibacterial Compounds ◽  
Ft Ir ◽  
Aldehyde Groups

Background: S. cristaefolium is the brown seaweed extracted using the serial technique with different solvents. Methods: S. cristaefolium powder (50 mesh) was extracted with hexane, ethyl acetate, and methanol respectively. The S. cristaefolium powder residue had been dried before being re-extracted with the next different solvents. Three serial extracts were obtained and named as the 1-stage extract, 2-stage extract, and 3-stage extract. Besides, a single-step extract (extraction using only methanol) was also produced to compare with three serial extracts in antibacterial activity tests (against E. coli and S. aureus). The three serial extracts were detected their antibacterial compounds using GC-MS, LC-HRMS, and FT-IR. Results: The 3-stage extract had the highest extraction yield. On S. aureus, the inhibition zone in all extracts was not significantly different. On E.coli, the highest inhibition zone (5.42±0.14 mm) was the 3-stage extract, indeed it is higher than both antibiotic and a single-step extract. Phenol, 9-Tricosene(Z)-, palmitic acid, and oleamide were contained in all extracts. Other antibacterial compound types, both the 1-stage and 2-stage extracts contained 8 types whilst the 3-stage extract contained the most types (12 types). Particularly, hexyl cinnamic aldehyde and betaine were detected only in the 3-stage extract with the dominant area. The carboxylic acid groups were detected in all extracts to confirm the fatty acid structure. Several cinnamic aldehyde groups were detected only in the 3-stage extract. Conclusions: Thus, the extraction technique serially could produce the 3-stage extract which has the strongest antibacterial activity and the richest antibacterial compounds.

Evidence for a repeating cross-beta sheet structure in the adenovirus fibre.

1983 ◽  
Vol 2 (8) ◽  
pp. 1357-1365 ◽  
Author(s):  
N.M. Green ◽  
N.G. Wrigley ◽  
W.C. Russell ◽  
S.R. Martin ◽  
A.D. McLachlan
Keyword(s):  
Beta Sheet ◽  
Beta Sheet Structure ◽  
Sheet Structure

Antibacterial Activity of Traditional Medicine Scurrula atropurpurea (BL) DANS and their Endophytic Fungi

2020 ◽  
Vol 840 ◽  
pp. 205-213
Author(s):  
Elfita Elfita ◽  
Muharni Muharni ◽  
Mardiyanto Mardiyanto ◽  
Fitrya Fitrya ◽  
Feti Fera ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Endophytic Fungi ◽  
Bacterial Infections ◽  
Salmonella Typhi ◽  
Spectroscopy Analysis ◽  
Chromatography Method ◽  
Antibacterial Compounds ◽  
Activity Test ◽  
Antibacterial Compound ◽  
Promising Source

Scurrula atropurpurea known as benalu is a medicinal plant that has been used for the treatment of various diseases such as antibacterial. Plants with ethnomedicine history use to cure pathogenic bacterial infections and their endophytic fungi is a promising source of antibacterial compounds. This study aimed to compared the antibacterial activity of S. atropurpurea leaves and their endophytic fungi. The secondary metabolites were isolated from the leaves of S. atropurpurea and their endophytic fungi by the chromatography method. The antibacterial activity test was carried out by Kirby Bauer method against Salmonella typhi (IPCCCB.11.669) and Escherichia coli (ATCC 25922) as Gram (-) and Bacillus subtilis (ATCC 6633) and Staphylococcus aureus (ATCC 25923) as Gram (+). The antibacterial compound from S. atropurpurea was determined by spectroscopy analysis as Quercetin-3-O-α-L-Rhamnopyranoside, while the antibacterial compound from endophytic fungi (strain BB1) as a lactone. Phylogenetic tree of strain BB1 has the highest homology with Neopestalotiopsis surinamensis strain CBS 450.74.

PURIFICATION OF LYSOZYME BY INTRINSICALLY SHIELDED HYDROGEL BEADS

2013 ◽  
Vol 27 (19) ◽  
pp. 1341028
Author(s):  
CONG LI ◽  
R. ZHANG ◽  
L. WANG ◽  
A. BOWYER ◽  
R. EISENTHAL ◽  
...  
Keyword(s):  
Binary Mixture ◽  
High Purity ◽  
High Selectivity ◽  
Egg White ◽  
Titration Calorimetry ◽  
Binding Affinities ◽  
Affinity Separation ◽  
Hydrogel Beads ◽  
Relative Binding ◽  
Very High

Macro-sized intrinsically shielded hydrogel beads have been prepared from BSA and CM-dextran grafted with CB using a technique based on freeze-thawing gelation method. The size of the beads lies in around 500 μm. Isothemal titration calorimetry (ITC) showed that the relative binding affinities of the lysozyme for CB, compared with BSA, at pH 3.0 was stronger than that at pH 7.4. They were employed for the affinity separation of lysozyme using chromatography column. Their adsorption capacity for lysozyme at pH 3.0 is higher than that at pH 9. In a binary mixture of lysozyme and ovalbumin, the beads showed very high selectivity toward lysozyme. Lysozyme of very high purity (> 93%) was obtained from a mixture of lysozyme and ovalbumin, and 85% from egg white solution. The results indicate that the macro-sized bead can be used for the separation, purification, and recovery of lysozyme in a chromatograph column.

Interaction of Humic Acid with Graphene Oxide: Relation to Antibacterial Activities Against Escherichia coli

2021 ◽  
Vol 21 (3) ◽  
pp. 1430-1438
Author(s):  
Hongyang Yu ◽  
Runxuan Chu ◽  
Xue Li ◽  
Bing Wang ◽  
Wei Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Graphene Oxide ◽  
Humic Acid ◽  
Environmental Remediation ◽  
Saline Solution ◽  
Antibacterial Activities ◽  
Titration Calorimetry ◽  
E Coli ◽  
Dose Dependent

Graphene oxide (GO) sheets attracted great attention as effectively antibacterial agents in water treatment and environmental remediation applications. In the study, the interaction of humic acid (HA) as the model of natural organic matter (NOM) with GO and their antibacterial activities against Escherichia coli (E. coli) was investigated. The interaction between GO and HA molecules was analyzed by isothermal titration calorimetry (ITC) and fluorescence spectroscopy analysis. The study demonstrated that GO reaction with HA was a spontaneously exothermic process, which enabled formation of stable and well dispersed GO-HA complex in aqueous solution. Both GO and GO-HA could significantly inhibit the growth of E. coli and present dose-dependent bactericidal property. GO and GO-HA showed more obvious antibacterial activity in saline solution than in LB broth. We suggest the surface wrinkles of GO and GO-HA could contribute to the firm wrapping of E. coli, which is the principle factor for the antibacterial activity of GO and GO-HA. Especially, GO-HA exhibit less surface wrinkles in comparison with GO, corresponding to its reduced antibacterial activity in saline solution.

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