scholarly journals Caves as a source of new antimicrobial agents: the case study of antibacterial activity from microorganisms inhabiting Cerâmica Cave, Portugal

2018 ◽  
Vol 1 ◽  
Author(s):  
André Gouveia ◽  
Ana Sofia Reboleira ◽  
Fernando Gonçalves ◽  
Sérgio Marques
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Agents ◽  
Extreme Environments ◽  
Antagonistic Activity ◽  
Aeromonas Salmonicida ◽  
Drug Resistant ◽  
Massif Central ◽  
Dry Heat ◽  
Track Record ◽  
Stable Conditions

Antibiotics have been developed for more than 80 years but presently there is an evident decline on their effectiveness due to the development of resistance by pathogens. The arising of multi drug resistant pathogens, has become a serious threat to public health. Microorganisms play a central role in nature as well as in drug discovery with a long track record as important sources of bioactive natural products revealing a wide array of molecules. Although many approaches have been applied to solve this crisis, in the last decades the focus on extreme habitats as gain attention due to peculiar features and due to the presence of unique microbial populations inhabiting these ecosystems. Caves are considered extreme environments, usually oligotrophic, being in general devoid of light, and presenting stable conditions (temperature, humidity) throughout the year. We present the first analysis of antimicrobial activity of bacteria isolated from Cerâmica Cave, located in the Sicó karst massif, central Portugal. Microorganism acquisition was performed through a variety of physical and chemical treatments: dry-heat, wet-heat, dry-heat plus phenol (1,5%), phenol (1,5%), microwave irradiation, rehydration centrifugation, and no-treatment, along with three media: R2A agar, Actinomycetes isolation agar and Yeast-malt agar. A primary antimicrobial activity screening, through cross streak method, was performed in 28 isolates, using two different incubation periods and different target agents (Staphylococcus aureus, Bacillus cereus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Aeromonas salmonicida, Salmonella typhimurium and Enterococcus faecalis). A total of 7 isolates presented antagonistic activity against B. cereus, P. aeruginosa, E. coli, A. salmonicida S. typhimurium and S. aureus. This study proves the ability of cave microorganisms to inhibit both Gram positive and Gram negative pathogenic strains, highlighting the potential of caves microbiome to be one of the answers to solve the current global crisis of multi drug resistant pathogens.

New Oxadiazole Derivatives: Synthesis and Appraisal of Their Potential as Antimicrobial Agents

2018 ◽  
Vol 15 (1) ◽  
pp. 21-30
Author(s):  
Deboleena Dhara ◽  
Dhanya Sunil ◽  
Pooja R. Kamath ◽  
K. Ananda ◽  
S. Shrilakshmi ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Agents ◽  
Drug Resistant ◽  
Bacterial Strains ◽  
Spectral Techniques ◽  
Docking Simulations ◽  
E Coli ◽  
Oxadiazole Derivatives ◽  
Bacteria And Fungi ◽  
Almost All

Introduction: The escalating threat due to dwindling effect of antibiotics and challenge of tackling rising drug-resistant infections has gathered high focus in current medicinal research. Methods: In an attempt to find new molecules that can defeat microbial resistance, two new series of 2-[2-substituted ethenyl]-5-(substituted methoxy)-1,3,4-oxadiazole derivatives were synthesized. Various aromatic hydrazides were allowed to undergo cyclization to substituted oxadiazole-2- amines in the presence of cyanogen bromide and further condensed with different heterocyclic aldehydes to give new oxadiazole derivatives. The synthesized molecules were fully characterized by various spectral techniques and tested for antimicrobial activity. Results: Almost all the newly synthesized compounds especially (5g-5l) displayed remarkable growth inhibition against three bacterial strains: M. smegmatis, S. aureus, E. coli and fungi C. albicans. The antimicrobial activity was further confirmed by MIC assay against the same microorganisms. Oxadiazole 5g displayed promising activity with a MIC value of 0.025 mM for two bacteria and fungi, whereas MIC of this compound for E. coli was 0.1 mM. Other active compounds (5h-5l) also exhibited good MIC ranging between 0.313 to 5.0 mM against the selected microorganisms. Docking simulations were generated to explore the potential binding approaches of ligand 5g at the D-alanine:d-alanine ligase (Ddl) protein of E. coli and S. aureus. Conclusion: Molecule 5g was active even at a lower concentration and could probably act as a prospective lead molecule for targeting the drug resistant microorganisms.

scholarly journals Discovery of Actinomycetes from Extreme Environments with Potential to Produce Novel Antibiotics

2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Lyudmila Trenozhnikova ◽  
Azliyati Azizan
Keyword(s):  
Antimicrobial Agents ◽  
Extreme Environments ◽  
Antibacterial Activities ◽  
Antimicrobial Activities ◽  
Culture Conditions ◽  
Drug Resistant ◽  
Great Opportunity ◽  
Pure Cultures ◽  
High Concentrations ◽  
Novel Antibiotics

Introduction: Antimicrobial-resistant pathogens pose serious challenges to healthcare institutions and health of the public. Thus, there is an urgent need for the discovery of new and effective antimicrobial agents.  Microorganisms that exist in extreme environments such as those with high salinity or alkalinity, are known as extremophiles, and include various species of actinomycetes. The goal of this study is to discover novel antibiotics from extremophiles found in Kazakhstan that are effective against drug resistant pathogens.Methods: Soil from extreme environments of Kazakhstan was collected, and pure cultures of actinomycetes were isolated and cultured in modified Bennett’s broth with either high concentrations of salt or high pH to mimic extreme environments. Extracts obtained from selected actinomycetes strains were used to test for antimicrobial activity against Staphylococcus aureus, Escherichia coli and Aspergillus niger.Results: A total of 5936 strains of extremophile actinomycetes were isolated; from these, 2019 strains were further isolated into pure cultures. Of these, 415 actinomycetes strains that demonstrated antagonistic antibacterial activities were selected.  These actinomycetes were further classified into groups and subgroups based on their responses to different culture conditions. Antimicrobial antagonism activity for some of the actinomycetes strains was dependent on culture conditions and development of  aerial mycelia under extreme conditions.Conclusion: We identified several interesting candidate extracts with putative antimicrobial activities against several strains of drug resistant pathogens. Our research of the actinomycetes’ ability to produce antibiotics in the near-natural conditions provides a great opportunity to assess their biodiversity and distribution in the Central Asian region and to develop new methodological approaches to the screening of new antimicrobial agents.

Antimicrobial activity of 5-membered nitroheteroaromatic compounds beyond nitrofurans and nitroimidazoles: recent progress

2021 ◽  
Vol 28 ◽  
Author(s):  
Stanislav Kalinin ◽  
Tatiana Vedekhina ◽  
Polina Paramonova ◽  
Mikhail Krasavin
Keyword(s):  
Antimicrobial Activity ◽  
Nitro Group ◽  
Recent Progress ◽  
Antimicrobial Agents ◽  
Multidrug Resistant ◽  
Drug Resistant ◽  
Reductive Activation ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Primary Focus

: The last decade has been characterized by the development and approval of pretomanid and delamanid, which are nitroimidazole based drugs for multidrug resistant tuberculosis. This attracted renewed attention to the nitroheterocyclic scaffolds as a source of safe and efficient antimicrobial agents. While the primary focus is still on nitrofurans and nitroimidazoles, well known as bioreducible prodrugs, a number of studies have been published on other 5-membered nitroheteroaromatic compounds. The latter not only show promising antimicrobial activity, but also demonstrate modes of action different from the conventional reductive activation of nitro group. Considering the potential of these efforts to impact in the continuing race against drug-resistant pathogens, herein we review non-furan/imidazole based 5-membered nitroheteroaromatics investigated as antimicrobial agents in 2010-2020.

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.

NMR Assisted Antimicrobial Peptide Designing: Structure Based Modifications and Functional Correlation of a Designed Peptide VG16KRKP

2020 ◽  
Vol 27 (9) ◽  
pp. 1387-1404 ◽  
Author(s):  
Karishma Biswas ◽  
Humaira Ilyas ◽  
Aritreyee Datta ◽  
Anirban Bhunia
Keyword(s):  
Antimicrobial Agents ◽  
Biological Properties ◽  
Structure Characterization ◽  
Drug Resistant ◽  
Functional Correlation ◽  
Naturally Occurring ◽  
High Resolution Nmr ◽  
Different Types ◽  
Reduced Activity ◽  
Poor Stability

Antimicrobial Peptides (AMPs), within their realm incorporate a diverse group of structurally and functionally varied peptides, playing crucial roles in innate immunity. Over the last few decades, the field of AMP has seen a huge upsurge, mainly owing to the generation of the so-called drug resistant ‘superbugs’ as well as limitations associated with the existing antimicrobial agents. Due to their resilient biological properties, AMPs can very well form the sustainable alternative for nextgeneration therapeutic agents. Certain drawbacks associated with existing AMPs are, however, issues of major concern, circumventing which are imperative. These limitations mainly include proteolytic cleavage and hence poor stability inside the biological systems, reduced activity due to inadequate interaction with the microbial membrane, and ineffectiveness because of inappropriate delivery among others. In this context, the application of naturally occurring AMPs as an efficient prototype for generating various synthetic and designed counterparts has evolved as a new avenue in peptide-based therapy. Such designing approaches help to overcome the drawbacks of the parent AMPs while retaining the inherent activity. In this review, we summarize some of the basic NMR structure based approaches and techniques which aid in improving the activity of AMPs, using the example of a 16-residue dengue virus fusion protein derived peptide, VG16KRKP. Using first principle based designing technique and high resolution NMR-based structure characterization we validate different types of modifications of VG16KRKP, highlighting key motifs, which optimize its activity. The approaches and designing techniques presented can support our peers in their drug development work.

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.

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