Antimicrobial Peptide-Templated Silver Nanoclusters with Membrane Activity for Enhanced Bacterial Killing

2020 ◽  
Vol 20 (3) ◽  
pp. 1425-1433 ◽  
Author(s):  
Xingshu Fei ◽  
Xiaochuan Ma ◽  
Ge Fang ◽  
Yu Chong ◽  
Xin Tian ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Mammalian Cells ◽  
Energy Production ◽  
Antimicrobial Agents ◽  
Silver Nanoclusters ◽  
Bacterial Membrane ◽  
Respiratory Chain Complexes ◽  
Bacterial Killing ◽  
Chain Complexes ◽  
Ros Accumulation

We aimed to develop antimicrobial agents that satisfy biosafety considerations while exhibiting efficient antimicrobial activity. Peptide-capped silver nanoclusters (peptide@AgNCs) were designed. In addition, the antimicrobial activity and mechanism of peptide@AgNCs were studied. The hemolysis and cytotoxicity tests on mammalian cells were used to confirm the biocompatibility of peptide@ AgNCs. KLA@AgNCs exhibited dramatic antimicrobial activity without inducing significant cytotoxicity in mammalian cells. The KLA@AgNCs destroyed the integrity of the bacterial membrane and induced ROS accumulation, causing oxidative damage to biomolecules. The malfunction of the respiratory chain complexes I and V completely suppresses the energy production, ultimately accelerating the death of the bacteria. Our findings may advance the development of Ag-based nanomaterials with enhanced bactericidal activity and improved biocompatibility.

scholarly journals SPS-neutralization in tissue samples for efficacy testing of antimicrobial peptides

2019 ◽  
Author(s):  
Gabrielle Dijksteel ◽  
Peter Nibbering ◽  
Magda Ulrich ◽  
Esther Middelkoop ◽  
Bouke Boekema
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Peptides ◽  
Antimicrobial Agents ◽  
Ex Vivo ◽  
Accurate Determination ◽  
Residual Activity ◽  
Antimicrobial Effect ◽  
Complete Recovery ◽  
Bacterial Killing ◽  
Tissue Samples

Abstract Background Accurate determination of the efficacy of antimicrobial agents requires neutralization of residual antimicrobial activity in the samples before microbiological assessment of the number of surviving bacteria. Sodium polyanethol sulfonate (SPS) is a known neutralizer for the antimicrobial activity of aminoglycosides and polymyxins. In this study, we evaluated the ability of SPS to neutralize residual antimicrobial activity of antimicrobial peptides [SAAP-148 and pexiganan; 1% (wt/v) in PBS], antibiotics [mupirocin (Bactroban) and fusidic acid (Fucidin) in ointments; 2% (wt/wt))] and disinfectants [2% (wt/wt) silver sulfadiazine cream (SSD) and 0.5% (v/v) chlorhexidine in 70% alcohol]. Methods Homogenates of human skin models that were exposed to various antimicrobial agents for 1 h were pipetted on top of Methicillin-resistant Staphylococcus aureus (MRSA) on agar plates to demonstrate the presence of residual antimicrobial activity in tissue samples. To determine the efficacy of SPS in neutralization, various antimicrobial agents were mixed with PBS, 0.05%, 0.1%, 0.5% or 1% (wt/v) SPS in PBS. Subsequently, 10^5 colony forming units (CFU) MRSA were added to the mixtures and these were incubated for 30 min to determine the antimicrobial effect. Ex vivo excision wound models were inoculated with 10^5 CFU MRSA for 1 h and exposed to SAAP-148, pexiganan, chlorhexidine or PBS for 1 h to study the effect of SPS-neutralization on the bacterial killing of these antimicrobials. To quantify the number of surviving bacteria, 10-fold serial dilutions of the homogenates were cultured overnight on agar plates. Results All tested antimicrobials displayed residual activity in tissue samples, resulting in a lower recovery of surviving bacteria on agar. SPS concentrations at ≥0.05% (wt/v) were able to neutralize the antimicrobial activity of SAAP-148, pexiganan and chlorhexidine, resulting in the complete recovery of bacteria. However, SPS did not neutralize the activity of SSD, Bactroban and Fucidin. Finally, SPS-neutralization in ex vivo efficacy tests of SAAP-148 (p<0.001), pexiganan (p<0.05) and chlorhexidine (p<0.01) resulted in at least 10-fold higher numbers of MRSA compared to control samples without SPS-neutralization. Conclusion SPS can be used for the neutralization of residual activity of different antimicrobials, including SAAP-148, pexiganan and chlorhexidine and this prevents an overestimation of their efficacy.

Synthesis and Antimicrobial Activity of Thiohydantoins Obtained from L-Amino Acids

2019 ◽  
Vol 17 (1) ◽  
pp. 94-102 ◽  
Author(s):  
Priscila Goes Camargo de Carvalho ◽  
Jhonatan Macedo Ribeiro ◽  
Renata Perugini Biasi Garbin ◽  
Gerson Nakazato ◽  
Sueli Fumie Yamada Ogatta ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Mammalian Cells ◽  
Antimicrobial Agents ◽  
Ammonium Thiocyanate ◽  
Antibiofilm Activity ◽  
Bacterial Strains ◽  
Wide Range ◽  
Time Kill

Background: Thiohydantoins are an important class of heterocyclic compounds in drug discovery since they are related to a wide range of biological properties including antimicrobial activity. Objective: The objective of this study was to synthesize a series of thiohydantoins derived from Laminoacids and to evaluated their inhibitory effect on the growth of Gram-negative and Grampositive bacteria. Methods: All title compounds were synthetized by reaction of L-amino acids with thiourea or ammonium thiocyanate. Their antimicrobial activities were evaluated against bacterial strains by broth microdilution assays. The time-kill kinetics, the antibiofilm activity and the cytotoxicity to mammalian cells were determined for the compound that exhibited the best antimicrobial profile (1b). Results: Eleven thiohydantoins were readily obtained in good yields (52-95%). In general, thiohydantoins were more effective against Gram-positive bacteria. Compound 1b (derived from Lalanine) showed the best antibacterial activity against Staphylococcus epidermis ATCC 12228 and S. aureus BEC 9393 with MIC values of 940 and 1921 µM, respectively. The time-kill kinetics demonstrated time-dependent bactericidal effect in both strains for this derivative. Besides, 1b also exhibited antibacterial activity against biofilms of S. epidermidis ATCC 12228, leading to a 40% reduction in their metabolic activity compared to the untreated control. No cytotoxicity of 1b to mammalian cells was observed at MIC values. Conclusion: The data reported herein indicate relevant antimicrobial activity of thiohydantoins derived from L-aminoacid, mainly 1b, as potential pharmacophore to guide further chemical modification aiming at the search for new and improved antimicrobial agents.

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION OF 3-FORMYL INDOLE BASED SCHIFF BASES

2018 ◽  
Vol 7 (6) ◽  
Author(s):  
Singh Gurvinder ◽  
Singh Prabhsimran ◽  
Dhawan R. K.
Keyword(s):  
Antimicrobial Activity ◽  
Spectral Analysis ◽  
Schiff Bases ◽  
Antimicrobial Agents ◽  
Biological Evaluation ◽  
Fungal Strain ◽  
Bacterial Strains ◽  
Standard Drug ◽  
Gram Negative ◽  
E Coli

In order to develop new antimicrobial agents, a series of 3-formyl indole based Schiff bases were synthesized by reacting 3-formyl indole(indole-3-carboxaldehyde) with substituted aniline taking ethanol as solvent. The reaction was carried in the presence of small amount of p-toluene sulphonic acid as catalyst.All the synthesized compounds were characterized by IR, 1H-NMR spectral analysis. All the synthesized compounds were evaluated for antimicrobial activity against two gram positive bacterial strains (B. subtilisand S. aureus) and two gram negative bacterial strains (P. aeruginosaand E. coli) and one fungal strain (C. albicans). All the synthesized compounds were found to have moderate to good antimicrobial activity. The  standard drug amoxicillin, fluconazole were used for antimicrobial activity. Among the synthesized compounds, the maximum antimicrobial activity was shown by compounds GS04, GS07, GS08 and GS10.

Assessment of Antimicrobial Activity and total Polyphenol Content of Rosa multiflora and Rosa wichuraiana

2019 ◽  
Vol 10 (04) ◽  
pp. 646-650
Author(s):  
Hyeusoo Kim ◽  
Kyeong Won Yun
Keyword(s):  
Antimicrobial Activity ◽  
Ethyl Acetate ◽  
Antimicrobial Agents ◽  
Ethyl Acetate Fraction ◽  
Rosa Multiflora ◽  
Polyphenol Content ◽  
Total Polyphenol ◽  
Water Fraction ◽  
Total Polyphenol Content ◽  
Rosa Species

The fruit of Rosa multiflora has been used as traditional herbal medicine in Asian countries. The present investigation was undertaken to study the antimicrobial activity and total polyphenol content of hexane, ether, ethyl acetate, water fraction of methanol extract of fruit and flower from Rosa multiflora and Rosa wichuraiana. Antimicrobial activity of the mentioned fractions against 3 gram-positive and 4 gram-negative bacteria using disk diffussion method. The measurement of minimal inhibition concentration (MIC) showed that the ethyl acetate fraction of the two Rosa species is the most effective against the tested bacteria. The total polyphenol content of ethyl acetate fraction of the two Rosa species is higher than the other fractions. The results indicate the antimicrobial activity was related with the total polyphenol content and the fruit and flower of the two Rosa species can be considered as a natural source of antimicrobial agents.

The Chemistry Of Antibiofilm Phytocompounds.

2020 ◽  
Vol 20 ◽  
Author(s):  
Dibyajit Lahiri ◽  
Moupriya Nag ◽  
Sayantani Garai ◽  
Rina Rani Ray
Keyword(s):  
Antimicrobial Activity ◽  
Antibiotic Resistance ◽  
Antibiotic Therapy ◽  
Antimicrobial Agents ◽  
Chemical Nature ◽  
Rapid Development ◽  
Wide Spread ◽  
Chronic Infections ◽  
Therapeutic Uses

: Phytocompounds are long known for their therapeutic uses due to their competence as antimicrobial agents. The antimicrobial activity of these bioactive compounds manifests their ability as an antibiofilm agent and is thereby proved to be competent to treat the wide spread of biofilm-associated chronic infections. Rapid development of antibiotic resistance in bacteria has made the treatment of these infections almost impossible by conventional antibiotic therapy, which forced in the switch over to the use of phytocompounds. The present overview deals with the classification of the huge array of phytocompounds according to their chemical nature, detection of their target pathogen, and elucidation of their mode of action.

Copper-catalyzed Convenient Synthesis and SAR Studies of Substituted-1,2,3-triazole as Antimicrobial Agents

2018 ◽  
Vol 16 (1) ◽  
pp. 3-10
Author(s):  
Aniket P. Sarkate ◽  
Kshipra S. Karnik ◽  
Pravin S. Wakte ◽  
Ajinkya P. Sarkate ◽  
Ashwini V. Izankar ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Antifungal Activity ◽  
Antimicrobial Agents ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
One Pot ◽  
Triazole Derivatives ◽  
Sar Studies ◽  
Convenient Synthesis ◽  
Antibacterial And Antifungal

Background:A novel copper-catalyzed synthesis of substituted-1,2,3-triazole derivatives has been developed and performed by Huisgen 1,3-dipolar cycloaddition reaction of azides with alkynes. The reaction is one-pot multicomponent.Objective:We state the advancement and execution of a methodology allowing for the synthesis of some new substituted 1,2,3-triazole analogues with antimicrobial activity.Methods:A series of triazole derivatives was synthesized by Huisgen 1,3-dipolar cycloaddition reaction of azides with alkynes. The structures of the synthesized compounds were elucidated and confirmed by 1H NMR, IR, MS and elemental analysis. All the synthesized compounds were tested for their antimicrobial activity against a series of strains of Bacillus subtilis, Staphylococcus aureus and Escherichia coli for antibacterial activity and against the strains of Candida albicans, Aspergillus flavus and Aspergillus nigar for antifungal activity, respectively.Results and Conclusion:From the antimicrobial data, it was observed that all the newly synthesized compounds showed good to moderate level of antibacterial and antifungal activity.

Synthesis of Novel 3(N,N-dialkylamino)alkyl/phenyl Substituted Thieno [2,3-d]pyrimidinones as H1-Anti-Histaminic and Antimicrobial Agents

2019 ◽  
Vol 15 (1) ◽  
pp. 63-70
Author(s):  
Shiv Dev Singh ◽  
Arvind Kumar ◽  
Firoz Babar ◽  
Neetu Sachan ◽  
Arun Kumar Sharma
Keyword(s):  
Antimicrobial Activity ◽  
Potassium Hydroxide ◽  
Antimicrobial Agents ◽  
Pyrimidine Ring ◽  
Antimicrobial Activities ◽  
Screening Methods ◽  
Chlorpheniramine Maleate ◽  
In Vivo Screening

Background: Thienopyrimidines are the bioisoster of quinazoline and unlike quinazoline exist in three isomeric forms corresponding to the three possible types annulation of thiophene to the pyrimidine ring viz thieno[2,3-d] pyrimidine, thieno[3,2-d] pyrimidine and thieno[3,4-d]pyrimidine. Heterocyclic containing the thienopyrimidinone moiety exhibits various pronounced activities such as anti-hypertensive, analgesic and anti-inflammatory, antiviral, platelet aggregation inhibitory, antiprotozoal bronchodilatory, phosphodiesterase inhibitory, antihistaminic, antipsychotic and antimicrobial activity. Objective: Synthesis of novel 3(N,N-dialkylamino)alkyl/phenyl substituted thieno[2,3-d]pyrimidinones as H1-anti-histaminic and antimicrobial agents. Methods: A series of 3-[(N,N-dialkylamino)alkyl/phenyl]-2-(1H)thioxo-5,6,7,8-tetrahydrobenzo(b) thieno(2,3-d)pyrimidine-4(3H)-ones[4a-d], their oxo analogous [5a-d] and 3-[(N,N-dialkylamino)alkyl]- 2-chlorophenyl-5,6,7,8-tetrahydrobenzo(b)thieno(2,3-d)pyrimidine- 4 (3H)-ones[6a-d]derivative were synthesized from 2-amino-4,5,6,7-tetrahydrobenzo(b)thiophene-3-carboxylic acid by nucleophilic substitution of different N,N-dialkyl alkylene/phenylene diamines on activated 3-acylchloride moiety followed by cyclocondensation with carbon disulfide and ethanolic potassium hydroxide to get [4a-d] and in second reaction by condensation with 4-chlorobenzoyl chloride to get [6a-d] by single pot novel innovative route. The oxo analogous [5a-d] were prepared by treating derivatives [4a-d] with potassium permagnate in ethanolic KOH. The synthesized compound were evaluated for H1-antihistaminic and antimicrobial activities. Results: All synthesized compounds exhibited significant H1-antihistaminic activity by in vitro and in vivo screening methods and data were verified analytically and statistically. The compound 4a, 4b, 5a and 5b showed significant H1-antihistaminiic activity than the reference standard chlorpheniramine maleate. The compound 6d, 6c, 5c and 4c exhibited significant antimicrobial activity.

scholarly journals Chemical Compositions, Mosquito Larvicidal and Antimicrobial Activities of Essential Oils from Five Species of Cinnamomum Growing Wild in North Central Vietnam

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1303 ◽  
Author(s):  
Do N. Dai ◽  
Nguyen T. Chung ◽  
Le T. Huong ◽  
Nguyen H. Hung ◽  
Dao T.M. Chau ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oil ◽  
Essential Oils ◽  
Larvicidal Activity ◽  
Antimicrobial Agents ◽  
Chemical Compositions ◽  
North Central ◽  
Mosquito Larvicidal Activity ◽  
Central Vietnam ◽  
Leaf Essential Oil

Members of the genus Cinnamomum (Lauraceae) have aromatic volatiles in their leaves and bark and some species are commercially important herbs and spices. In this work, the essential oils from five species of Cinnamomum (C. damhaensis, C. longipetiolatum, C. ovatum, C. polyadelphum and C. tonkinense) growing wild in north central Vietnam were obtained by hydrodistillation, analyzed by gas chromatography and screened for antimicrobial and mosquito larvicidal activity. The leaf essential oil of C. tonkinense, rich in β-phellandrene (23.1%) and linalool (32.2%), showed excellent antimicrobial activity (MIC of 32 μg/mL against Enterococcus faecalis and Candida albicans) and larvicidal activity (24 h LC50 of 17.4 μg/mL on Aedes aegypti and 14.1 μg/mL against Culex quinquefasciatus). Cinnamomum polyadelphum leaf essential oil also showed notable antimicrobial activity against Gram-positive bacteria and mosquito larvicidal activity, attributable to relatively high concentrations of neral (11.7%) and geranial (16.6%). Thus, members of the genus Cinnamomum from Vietnam have shown promise as antimicrobial agents and as potential vector control agents for mosquitoes.

scholarly journals Biological and Physico-Chemical Characteristics of Arginine-Rich Peptide Gemini Surfactants with Lysine and Cystine Spacers

2021 ◽  
Vol 22 (7) ◽  
pp. 3299
Author(s):  
Damian Neubauer ◽  
Maciej Jaśkiewicz ◽  
Marta Bauer ◽  
Agata Olejniczak-Kęder ◽  
Emilia Sikorska ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Amino Acid ◽  
Cationic Surfactants ◽  
Antimicrobial Agents ◽  
Gemini Surfactants ◽  
Antimicrobial Activities ◽  
Critical Aggregation Concentration ◽  
Cytotoxic Activities ◽  
Candida Sp ◽  
Enhanced Selectivity

Ultrashort cationic lipopeptides (USCLs) and gemini cationic surfactants are classes of potent antimicrobials. Our recent study has shown that the branching and shortening of the fatty acids chains with the simultaneous addition of a hydrophobic N-terminal amino acid in USCLs result in compounds with enhanced selectivity. Here, this approach was introduced into arginine-rich gemini cationic surfactants. L-cystine diamide and L-lysine amide linkers were used as spacers. Antimicrobial activity against planktonic and biofilm cultures of ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) strains and Candida sp. as well as hemolytic and cytotoxic activities were examined. Moreover, antimicrobial activity in the presence of human serum and the ability to form micelles were evaluated. Membrane permeabilization study, serum stability assay, and molecular dynamics were performed. Generally, critical aggregation concentration was linearly correlated with hydrophobicity. Gemini surfactants were more active than the parent USCLs, and they turned out to be selective antimicrobial agents with relatively low hemolytic and cytotoxic activities. Geminis with the L-cystine diamide spacer seem to be less cytotoxic than their L-lysine amide counterparts, but they exhibited lower antibiofilm and antimicrobial activities in serum. In some cases, geminis with branched fatty acid chains and N-terminal hydrophobic amino acid resides exhibited enhanced selectivity to pathogens over human cells.

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