scholarly journals Structure–Activity Relationship Assessment of Sophorolipid Ester Derivatives against Model Bacteria Strains

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 3021
Author(s):  
Filbert Totsingan ◽  
Fei Liu ◽  
Richard A. Gross
Keyword(s):  
Antimicrobial Activity ◽  
Butyl Ester ◽  
Head Group ◽  
Hydroxyl Groups ◽  
Dependent Manner ◽  
Human Pathogens ◽  
Gram Positive ◽  
Open Chain ◽  
Fermentation Products ◽  
Primary Hydroxyl

Sophorolipids (SLs) are glycolipids that consist of a hydrophilic sophorose head group covalently linked to a hydrophobic fatty acid tail. They are produced by fermentation of non-pathogenic yeasts such as Candida Bombicola. The fermentation products predominantly consist of the diacetylated lactonic form that coexists with the open-chain acidic form. A systematic series of modified SLs were prepared by ring opening of natural lactonic SL with n-alkanols of varying chain length under alkaline conditions and lipase-selective acetylation of sophorose primary hydroxyl groups. The antimicrobial activity of modified SLs against Gram-positive human pathogens was a function of the n-alkanol length, as well as the degree of sophorose acetylation at the primary hydroxyl sites. Modified SLs were identified with promising antimicrobial activities against Gram-positive human pathogens with moderate selectivity (therapeutic index, TI = EC50/MICB. cereus = 6–33). SL-butyl ester exhibited the best antimicrobial activity (MIC = 12 μM) and selectivity (TI = 33) among all SLs tested. Kinetic studies revealed that SL-ester derivatives kill B. cereus in a time-dependent manner resulting in greater than a 3-log reduction in cell number within 1 h at 2×MIC. In contrast, lactonic SL required 3 h to achieve the same efficiency.

scholarly journals Structure-Activity Relationships of Antimicrobial and Lipoteichoic Acid-Sequestering Properties in Polyamine Sulfonamides

2008 ◽  
Vol 53 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Hemamali J. Warshakoon ◽  
Mark R. Burns ◽  
Sunil A. David
Keyword(s):  
Antimicrobial Activity ◽  
Rational Design ◽  
Acyl Chain ◽  
Lipoteichoic Acid ◽  
Major Constituent ◽  
Dependent Manner ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Structure Activity

ABSTRACTWe have recently confirmed that lipoteichoic acid (LTA), a major constituent of the gram-positive bacterial surface, is the endotoxin of gram-positive bacteria that induces proinflammatory molecules in a Toll-like receptor 2 (TLR2)-dependent manner. LTA is an anionic amphipath whose physicochemical properties are similar to those of lipopolysaccharide (LPS), which is found on the outer leaflet of the outer membranes of gram-negative organisms. Hypothesizing that compounds that sequester LPS could also bind to and inhibit LTA-induced cellular activation, we screened congeneric series of polyamine sulfonamides which we had previously shown effectively neutralized LPS both in vitro and in animal models of endotoxemia. We observed that these compounds do bind to and neutralize LTA, as reflected by the inhibition of TLR2-mediated NF-κB induction in reporter gene assays. Structure-activity studies showed a clear dependence of the acyl chain length on activity against LTA in compounds with spermine and homospermine scaffolds. We then sought to examine possible correlations between the neutralizing potency toward LTA and antimicrobial activity inStaphylococcus aureus. A linear relationship between LTA sequestration activity and antimicrobial activity for compounds with a spermine backbone was observed, while all compounds with a homospermine backbone were equally active againstS. aureus, regardless of their neutralizing potency toward LTA. These results suggest that the number of protonatable charges is a key determinant of the activity toward the membranes of gram-positive bacteria. The development of resistance to membrane-active antibiotics has been relatively slower than that to conventional antibiotics, and it is possible that compounds such as the acylpolyamines may be useful clinically, provided that they have an acceptable safety profile and margin of safety. A more detailed understanding of the mechanisms of interactions of these compounds with LPS and LTA, as well as the gram-negative and -positive bacterial cell surfaces, will be instructive and should allow the rational design of analogues which combine antisepsis and antibacterial properties.

scholarly journals Antimicrobial Effect of Malaysian Honey on Some Human Pathogens: an in vitro Study

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Hassanain AT ◽  
Alyaa AK ◽  
Karim AJ
Keyword(s):  
Antimicrobial Activity ◽  
In Vitro Study ◽  
Antimicrobial Effect ◽  
Dilution Method ◽  
Human Pathogens ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Broth Dilution

Introduction: Honey has potent bactericidal activity against many pathogenic organisms, including various Gram-negative and Gram-positive bacteria. This study aimed to determine the antimicrobial effect of Malaysian honey against different species of human pathogens using optimized honey broth media. Materials and Methods: The antimicrobial activity of honey against standard strains of Gram-negative and Grampositive bacteria and yeast was tested in vitro by the broth dilution method using 10%-100% w/v concentrations prepared in tryptic soy broth. Results: Streptococcus pyogenes was the most sensitive pathogen, it was completely inhibited by 30% honey broth medium. The most resistant were E. faecalis, S. aureus and MRSA, but they were all completely inhibited by 80% honey broth medium. Conclusion: Honey is shown to possess antimicrobial activity against human Gram-positive and negative medically important bacteria.

scholarly journals Polynuclear Silver(I) Complex with Thianthrene: Structural Characterization, Antimicrobial Activity and Interaction with Biomolecules

Proceedings ◽  
2020 ◽  
Vol 67 (1) ◽  
pp. 4
Author(s):  
Darko P. Ašanin ◽  
Tina P. Andrejević ◽  
Sanja Skaro-Bogojevic ◽  
Nevena Lj. Stevanović ◽  
Ivana Aleksic ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Binding Affinity ◽  
Significant Activity ◽  
Human Pathogens ◽  
X Ray Diffraction ◽  
Candida Spp ◽  
Gram Positive ◽  
Minimal Inhibitory Concentrations ◽  
Calf Thymus ◽  
Vis Spectroscopy

New silver(I) complex with thianthrene (tia), [Ag(NO3)(tia)(H2O)]n, was synthesized by the reaction of AgNO3 with an equimolar amount of tia in ethanol/dichloromethane (v/v 1:1) at room temperature, and characterized by NMR, IR and UV-Vis spectroscopy and single-crystal X-ray diffraction analysis. The antimicrobial activity of the synthesized complex was evaluated against the broad panel of Gram-positive and Gram-negative bacteria and Candida spp. This complex showed significant activity toward important human pathogens Gram-positive Staphylococcus aureus and Candida parapsilosis with minimal inhibitory concentrations (MICs) being 3.91 µg/mL. The interaction of [Ag(NO3)(tia)(H2O)]n with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) was studied to evaluate the binding affinity towards these biomolecules for possible insights on the mode of antimicrobial activity. The binding affinity of the investigated complex to BSA is higher than that for DNA, indicating that proteins could be more favorable binding sites for this complex in comparison to the nucleic acids.

Antimicrobial Activity of Iron-Halide Complexes Against Gram-Positive and Gram-Negative Bacteria

2020 ◽  
Author(s):  
Nusrat Abedin ◽  
Abdullah Hamed A Alshehri ◽  
Ali M A Almughrbi ◽  
Olivia Moore ◽  
Sheikh Alyza ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Resistance ◽  
Extracellular Dna ◽  
Antibiofilm Activity ◽  
Gram Negative Bacteria ◽  
Bacterial Strains ◽  
Gram Positive ◽  
Gram Negative ◽  
Antimicrobial Substances ◽  
Mammalian Cell Lines

Antimicrobial resistance (AMR) has become one of the more serious threats to the global health. The emergence of bacteria resistant to antimicrobial substances decreases the potencies of current antibiotics. Consequently, there is an urgent and growing need for the developing of new classes of antibiotics. Three prepared novel iron complexes have a broad-spectrum antimicrobial activity with minimum bactericidal concentration (MBC) values ranging from 3.5 to 10 mM and 3.5 to 40 mM against Gram-positive and Gram-negative bacteria with antimicrobial resistance phenotype, respectively. Time-kill studies and quantification of the extracellular DNA confirmed the bacteriolytic mode of action of the iron-halide compounds. Additionally, the novel complexes showed significant antibiofilm activity against the tested pathogenic bacterial strains at concentrations lower than the MBC. The cytotoxic effect of the complexes on different mammalian cell lines show sub-cytotoxic values at concentrations lower than the minimum bactericidal concentrations.

Characteristics of the etiological structure and susceptibility to antibiotics, antiseptics of infectious pathogens of respiratory organs in children in critical states

2018 ◽  
Vol 22 (2) ◽  
pp. 311-317
Author(s):  
O.A. Nazarchuk ◽  
A.I. Starodub ◽  
O.V. Rymsha ◽  
V.A. Starodub ◽  
S.A. Kolodii
Keyword(s):  
Antimicrobial Activity ◽  
Antibacterial Agents ◽  
Inflammatory Diseases ◽  
Diffusion Method ◽  
Chlorhexidine Digluconate ◽  
Gram Positive ◽  
Critical States ◽  
Results Of Treatment ◽  
Moderate Resistance ◽  
Staphylococcus Spp

The study of the etiological structure, the properties of pathogens of the respiratory infectious diseases in children and their resistance to antibacterial agents is particularly relevant in modern conditions, expands the search for new approaches to combating pathogens, improves the results of treatment and reduces the mortality of this pathology. The aim — study of etiological structure, sensitivity to antibiotics and antiseptics of pathogens of infectious and inflammatory diseases of respiratory organs in children. In the study there were enrolled 247 patients who were treated in Vinnytsia Regional Children’s Clinical Hospital (VRCCH) in 2016. The sensitivity of microorganisms to 23 antibacterial agents was determined by the disc-diffusion method according to the generally accepted method. The analysis of the antimicrobial activity of antiseptic drugs (decamethoxine, miramistin, chlorhexidine digluconate) was performed by a double serial dilution technique with the determination of the minimum inhibitory bacteriostatic (MIC) and bactericidal (MBcC) concentrations, by the method of successive serial dilutions of the drug in a liquid nutrient medium. In patients who were in inpatient treatment at the VRCCH in 2016 because of pneumonia there were found opportunistic microorganisms which were of etiological significance in the development of the infection. Among them there were Streptococci (47,3 %), Staphylococci (15,3 %), Candida (13,3 %), Enterococci (10,9 %), including a high proportion of owned non-fermenting gram negative bacilli (9,8%) and species of Enterobacteria (2,0 %). Isolated strains of microorganisms had moderate resistance to most modern antibiotic drugs. The sensitivity of isolated strains of microorganisms to reserved antibiotics as carbapenems, often being used in the treatment of critical states of patients in the intensive care units, was found to above 18,2%. The sensitivity to this antibiotic in Enterococcus spp. (7,1 %), Staphylococcus spp. (5,9 %) was also low. Carbapenems, fluoroquinolones (the 1st and 2nd generations), antibiotics and aminoglycosides were found to be effective against gram positive microorganisms in more then 45% of cases. According to this they were considered to be as drugs of choice in the treatment of infectious and purulent-inflammatory pathology of respiratory organs, caused metitcilin- and vancomycin-resistant strains of microorganisms. Resistance to these drugs among investigated strains did not exceed 9,0 %. The high bactericidal properties of antiseptics as decamethoxine was determined against S.pyogenes, Staphylococcus spp. Its MBcC against these bacteria (1,65±0,20 mkg/ml and 4,32±0,50 mkg/ml, respectively) proved the advantage of decamethoxine’s effectiveness in comparison with chlorhexidine digluconate 3,14 times, 2,44 times miramistin. Clinical strains of C.albicans showed the highest susceptibility to decamethoxine, which fungicidal activity was determined in the presence (16,17±2,33 mkg/ml), in comparison with chlorxedine (MFtsK 27,59±3,59 mg/ml) and miramistin activity (27,59±3,595 mkg/ml). In children with inflammatory diseases of the respiratory organs gram-positive cocci are among the predominant pathogens (73,5 %) of cases, in the association allocated – 8,0 % of pathogens. Allocated strains of microorganisms were moderately resistant to all antibiotics studied. For antimicrobial activity antiseptic drugs, especially decamethoxine, have advantages over antibiotics confirming the possibility of their use in combination with systemic antibacterials.

Antimicrobial Activity For Crud EWatery Extract Of Seeds Of Citrus Aurantifolia (Lime Fruit) Against Gram Positive And Negative Bacteria In Vitro

2016 ◽  
pp. 404
Author(s):  
بهاء عبدالله لفتة الربيعى ◽  
هند حسين عبيد ◽  
تحرير هادى صالح
Keyword(s):  
Antimicrobial Activity ◽  
Gram Positive ◽  
Citrus Aurantifolia

scholarly journals Rational Design of Ag/ZnO Hybrid Nanoparticles on Sericin/Agarose Composite Film for Enhanced Antimicrobial Applications

2020 ◽  
Vol 22 (1) ◽  
pp. 105
Author(s):  
Wanting Li ◽  
Zixuan Huang ◽  
Rui Cai ◽  
Wan Yang ◽  
Huawei He ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Antimicrobial Activity ◽  
Composite Film ◽  
Water Absorption ◽  
Rational Design ◽  
Hybrid Nanoparticles ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
X Ray

Silver-based hybrid nanomaterials are receiving increasing attention as potential alternatives for traditional antimicrobial agents. Here, we proposed a simple and eco-friendly strategy to efficiently assemble zinc oxide nanoparticles (ZnO) and silver nanoparticles (AgNPs) on sericin-agarose composite film to impart superior antimicrobial activity. Based on a layer-by-layer self-assembly strategy, AgNPs and ZnO were immobilized on sericin-agarose films using the adhesion property of polydopamine. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction spectroscopy were used to show the morphology of AgNPs and ZnO on the surface of the composite film and analyze the composition and structure of AgNPs and ZnO, respectively. Water contact angle, swelling ratio, and mechanical property were determined to characterize the hydrophilicity, water absorption ability, and mechanical properties of the composite films. In addition, the antibacterial activity of the composite film was evaluated against Gram-positive and Gram-negative bacteria. The results showed that the composite film not only has desirable hydrophilicity, high water absorption ability, and favorable mechanical properties but also exhibits excellent antimicrobial activity against both Gram-positive and Gram-negative bacteria. It has shown great potential as a novel antimicrobial biomaterial for wound dressing, artificial skin, and tissue engineering.

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