Identification of N-Substituted Triazolo-azetidines as Novel Antibacterials using pDualrep2 HTS Platform

2019 ◽  
Vol 22 (5) ◽  
pp. 346-354
Author(s):  
Yan A. Ivanenkov ◽  
Renat S. Yamidanov ◽  
Ilya A. Osterman ◽  
Petr V. Sergiev ◽  
Vladimir A. Aladinskiy ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Large Scale ◽  
Underlying Mechanism ◽  
Luciferase Assay ◽  
Reporter System ◽  
E Coli ◽  
Starting Point ◽  
High Concentrations ◽  
Mic Value

Aim and Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity. Materials and Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out. Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position. Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.

Large-scale High-throughput Screening Revealed 5'-(carbonylamino)-2,3'- bithiophene-4'-carboxylate as Novel Template for Antibacterial Agents

2020 ◽  
Vol 17 (5) ◽  
pp. 716-724
Author(s):  
Yan A. Ivanenkov ◽  
Renat S. Yamidanov ◽  
Ilya A. Osterman ◽  
Petr V. Sergiev ◽  
Vladimir A. Aladinskiy ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
High Throughput ◽  
High Throughput Screening ◽  
Large Scale ◽  
Antibacterial Agents ◽  
Sos Response ◽  
Luciferase Assay ◽  
Translational Machinery ◽  
E Coli ◽  
New Class

Background: The key issue in the development of novel antimicrobials is a rapid expansion of new bacterial strains resistant to current antibiotics. Indeed, World Health Organization has reported that bacteria commonly causing infections in hospitals and in the community, e.g. E. Coli, K. pneumoniae and S. aureus, have high resistance vs the last generations of cephalosporins, carbapenems and fluoroquinolones. During the past decades, only few successful efforts to develop and launch new antibacterial medications have been performed. This study aims to identify new class of antibacterial agents using novel high-throughput screening technique. Methods: We have designed library containing 125K compounds not similar in structure (Tanimoto coeff.< 0.7) to that published previously as antibiotics. The HTS platform based on double reporter system pDualrep2 was used to distinguish between molecules able to block translational machinery or induce SOS-response in a model E. coli system. MICs for most active chemicals in LB and M9 medium were determined using broth microdilution assay. Results: In an attempt to discover novel classes of antibacterials, we performed HTS of a large-scale small molecule library using our unique screening platform. This approach permitted us to quickly and robustly evaluate a lot of compounds as well as to determine the mechanism of action in the case of compounds being either translational machinery inhibitors or DNA-damaging agents/replication blockers. HTS has resulted in several new structural classes of molecules exhibiting an attractive antibacterial activity. Herein, we report as promising antibacterials. Two most active compounds from this series showed MIC value of 1.2 (5) and 1.8 μg/mL (6) and good selectivity index. Compound 6 caused RFP induction and low SOS response. In vitro luciferase assay has revealed that it is able to slightly inhibit protein biosynthesis. Compound 5 was tested on several archival strains and exhibited slight activity against gram-negative bacteria and outstanding activity against S. aureus. The key structural requirements for antibacterial potency were also explored. We found, that the unsubstituted carboxylic group is crucial for antibacterial activity as well as the presence of bulky hydrophobic substituents at phenyl fragment. Conclusion: The obtained results provide a solid background for further characterization of the 5'- (carbonylamino)-2,3'-bithiophene-4'-carboxylate derivatives discussed herein as new class of antibacterials and their optimization campaign.

scholarly journals Fermentation and Extraction of Antibacterial Metabolite Using Streptomyces spp. Isolated from Taplejung, Nepal

2021 ◽  
Vol 26 (1) ◽  
pp. 8-15
Author(s):  
Shiv Nandan Sah ◽  
Ramesh Majhi ◽  
Sunil Regmi ◽  
Arjun Ghimire ◽  
Bhageshwor Biswas ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Salmonella Typhi ◽  
Soil Samples ◽  
E Coli ◽  
Primary Screening ◽  
Streptomyces Spp ◽  
Antibacterial Compound ◽  
Fermented Broth ◽  
Layer Chromatography ◽  
Mic Value

Realizing an increasing need for a novel antibiotic, this study was carried out to screen antibacterial metabolites producing actinomycetes from 15 soil samples collected from Taplejung. Antibacterial metabolites producing actinomycetes were confirmed by primary screening and secondary screening. Macroscopic, microscopic, and biochemical characteristics were used for presumptive identification of probable actinomycetes genera. The potential isolate was cultured in starch casein broth for production of possible antibacterial compound. The antibacterial compound was extracted from fermented broth using organic solvents like ethyl acetate, n-butanol, chloroform, dichloromethane, and methanol. Among 24 isolates, only one (T18) showed antibacterial activity against both Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli, Salmonella Typhi and Pseudomonas aeruginosa) test-bacteria. The isolate was considered as Streptomyces spp based on microscopy and various biochemical, and physiological characteristics. Extracted antibacterial metabolite showed antibacterial activity with a MIC value of 1.2 mg/mL against E. coli (ATCC 25922). The chromatogram in Thin Layer Chromatography showed only one spot exhibited by extract with Rf value 0.87 suggested that the isolate produced a compound that was completely different from the spot with Rf value 0.94 produced by gentamicin (standard). This study revealed the distribution of the potent antibacterial metabolite producing actinomycetes in the soils of Taplejung.

scholarly journals Evaluation of the Antibacterial Activity of 5-(thiophen-2-yl)-1H-tetrazole and Its Oxime Derivative against ATCC Reference Strains and Strains Isolated from the Hospital Environment of a Provincial Public Hospital in the City of Fez

2021 ◽  
Vol 2 (2) ◽  
pp. 16-24
Author(s):  
Sara Hajib ◽  
Mohamed Hssaini ◽  
Anouar Alami ◽  
Hicham Bekkari ◽  
Najoua Benchemsi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Resistance ◽  
Antibacterial Activities ◽  
Bactericidal Effect ◽  
Hospital Environment ◽  
Diffusion Method ◽  
E Coli ◽  
Tetrazole Derivatives ◽  
Reference Strains

Bacterial resistance to antibiotics and disinfectants has become a real concern. The hospital presents a favorable environment for the colonization and development of bacteria resistant to antibiotics and disinfectants. The search for new antimicrobial compounds is essential to combat this phenomenon. Tetrazole derivatives may represent a solution due to their interesting antibacterial activity. In this work, two tetrazole derivatives; thiophene-2-carbaldehyde (T2C) and 5-(thiophen-2-yl)-1H-tetrazole (5TPh-1HT), were evaluated for their antibacterial activities against a set of reference strains and strains isolated from the hospital environment. The antibacterial effect was studied by the disc diffusion method and by determination of MIC and MBC. The 5-(thiophen-2-yl)-1H-tetrazole (5TPh-1HT) has a broader spectrum of activity than its oxime derivative (T2C). The latter has bactericidal activity only on gram-negative Escherichia coli, Pseudomonas aeruginosa with MICs ranging from 0.62 mg/ml to 2.5 mg/ml, while 5TPh-1HT has a bactericidal effect on all strains with MICs ranging from 0.62 mg/ml to 1.25 mg/ml. Both products have a significant inhibitory activity on the strains tested in particular E. coli H, S. aureus H, P. aeruginosa and Streptococcus spp A. It was found that these activities vary depending on the microbial strain tested and the product applied.

scholarly journals β-Lactamase inhibition profile of new amidine-substituted diazabicyclooctanes

2021 ◽  
Vol 17 ◽  
pp. 711-718
Author(s):  
Zafar Iqbal ◽  
Lijuan Zhai ◽  
Yuanyu Gao ◽  
Dong Tang ◽  
Xueqin Ma ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Second Generation ◽  
Bacterial Species ◽  
The Other ◽  
Inhibition Activity ◽  
Bacterial Strains ◽  
E Coli ◽  
Mic Value

The diazabicyclooctane (DBO) scaffold is the backbone of non-β-lactam-based second generation β-lactamase inhibitors. As part of our efforts, we have synthesized a series of DBO derivatives A1–23 containing amidine substituents at the C2 position of the bicyclic ring. These compounds, alone and in combination with meropenem, were tested against ten bacterial strains for their antibacterial activity in vitro. All compounds did not show antibacterial activity when tested alone (MIC >64 mg/L), however, they exhibited a moderate inhibition activity in the presence of meropenem by lowering its MIC values. The compound A12 proved most potent among the other counterparts against all bacterial species with MIC from <0.125 mg/L to 2 mg/L, and is comparable to avibactam against both E. coli strains with a MIC value of <0.125 mg/L.

Synthesis, Characterization and Antibacterial Activity of Chitosan/TiO2 Microspheres

2014 ◽  
Vol 912-914 ◽  
pp. 362-365
Author(s):  
Wen Ying Qi ◽  
Sai Sai Chen ◽  
Dan Yang ◽  
Qin Long Li ◽  
Xiao Rong Wu ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Titanium Dioxide ◽  
Entrapment Efficiency ◽  
Aldehyde Group ◽  
Cross Linking ◽  
Amino Groups ◽  
E Coli ◽  
Ft Ir ◽  
Stretching Vibrations ◽  
Mic Value

In this study, chitosan (CS)/titanium dioxide (TiO2) microspheres with different nanoTiO2 content were obtained by suspension cross-linking technique and characterized by FT-IR and SEM. The strong peak of C=N stretching vibrations at 1641 cm-1 were found which demonstrated that amino groups of CS reacted with aldehyde group of glutaraldehyde. SEM photographs showed that the CS/TiO2 microspheres were spherical, and the size of the CS/TiO2 microspheres ranging from 50 to 170 μm was analyzed with the software of Image J. The entrapment efficiency of the CS/TiO2 microspheres was up to 67.7%. Compared with CS, CS/TiO2 microspheres had better antibacterial activity against S. aureus and E. coli with a MIC value of 0.0125%.

scholarly journals Antibacterial evaluation of Styrax pohlii and isolated compounds

2013 ◽  
Vol 49 (4) ◽  
pp. 653-658 ◽  
Author(s):  
Camila Spereta Bertanha ◽  
Susane Hellen Utrera ◽  
Valéria Maria Melleiro Gimenez ◽  
Milton Groppo ◽  
Márcio Luis Andrade e Silva ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Concentration ◽  
Ethanolic Extract ◽  
Preliminary Evaluation ◽  
Microdilution Method ◽  
Aerial Parts ◽  
Broth Microdilution Method ◽  
Weak Antibacterial Activity ◽  
Mic Value

The antibacterial activity of the compounds egonol (1) and homoegonol (2), of the crude ethanolic extract of Styrax pohlii (Styracaceae) aerial parts (EE), and of its n-hexane (HF), EtOAc (EF), n-BuOH (BF), and hydromethanolic (HMF) fractions was evaluated against the following microorganisms: Streptococcus pneumoniae (ATCC 6305), S. pyogenes (ATCC 19615), Haemophilus influenzae (ATCC 10211), Pseudomonas aeruginosa (ATCC 27853), and Klebsiella pneumoniae (ATCC 10031). The broth microdilution method was used for determination of the minimum inhibitory concentration (MIC) during preliminary evaluation of antibacterial activity. The EE yielded MIC values of 400 µg/mL for S. pneumoniae and P. aeruginosa and 300 µg/mL for H. influenzae. The HF and EF fractions exhibited enhanced antibacterial activity, with MIC values of 200 µg/mL against S. pneumoniae, but only EF displayed activity against H. influenzae (MIC 200 µg/mL). The best MIC value with compounds 1 and 2 (400 µg/mL) was obtained for (1) against S. pneumoniae and P. aeruginosa. Therefore, 1 exhibited weak antibacterial activity against these standard strains.

scholarly journals Deciphering the Role of V88L Substitution in NDM-24 metallo-β-lactamase

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 744 ◽  
Author(s):  
Liu ◽  
Piccirilli ◽  
Liu ◽  
Li ◽  
Wang ◽  
...  
Keyword(s):  
Functional Results ◽  
Analysis Data ◽  
New Delhi ◽  
Resistance Level ◽  
E Coli ◽  
Β Sheet ◽  
Substrate Hydrolysis ◽  
Mic Value

: The New Delhi metallo-β-lactamase-1 (NDM-1) is a typical carbapenemase and plays a crucial role in antibiotic-resistance bacterial infection. Phylogenetic analysis, performed on known NDM-variants, classified NDM enzymes in seven clusters. Three of them include a major number of NDM-variants. In this study, we evaluated the role of the V88L substitution in NDM-24 by kinetical and structural analysis. Functional results showed that V88L did not significantly increase the resistance level in the NDM-24 transformant toward penicillins, cephalosporins, meropenem, and imipenem. Concerning ertapenem, E. coli DH5α/NDM-24 showed a MIC value 4-fold higher than that of E. coli DH5α/NDM-1. The determination of the kcat, Km, and kcat/Km values for NDM-24, compared with NDM-1 and NDM-5, demonstrated an increase of the substrate hydrolysis compared to all the β-lactams tested, except penicillins. The thermostability testing revealed that V88L generated a destabilized effect on NDM-24. The V88L substitution occurred in the β-strand and low β-sheet content in the secondary structure, as evidenced by the CD analysis data. In conclusion, the V88L substitution increases the enzyme activity and decreases the protein stability. This study characterizes the role of the V88L substitution in NDM-24 and provides insight about the NDM variants evolution.

scholarly journals Screening of Antibiotic Producing Actinomycetes for Antibiosis from Soil of Siraha, Nepal

2017 ◽  
Vol 1 ◽  
pp. 20-25
Author(s):  
Shiv Nandan Sah ◽  
Binod Lekhak
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Concentration ◽  
Biochemical Characterization ◽  
Gram Negative Bacteria ◽  
E Coli ◽  
Primary Screening ◽  
Streptomyces Spp ◽  
Taxonomic Groups ◽  
Mic Value

The increasing need of novel antibiotics has provided a pace for the search of antibiotics from actinomycetes. Primary and secondary screenings of antibiotic producing actinomycetes from the soil of Siraha (75-600 m) were performed. The minimum inhibitory concentration of the metabolites was determined against E. coli. Macroscopic, microscopic and biochemical characterization were performed for the identification of presumptive genera. Characterization of the antibacterial substances was done by TLC. Among 92 isolates, 22 showed antibacterial activity against at least 1 bacterium out of 6 test bacteria used. Microscopy and other characteristics studies revealed that 19 (86.36%) were Streptomyces spp.,1 (4.55%) was Thermomonospora spp., and 2 (9.09 %) were unidentified. Five potent isolates were selected for the secondary screening where 2 isolates inhibited Gram negative bacteria with an MIC value of 1.2 mg/mL for each isolate. TLC showed that both antibiotics produced only one spot suggesting the presence of one active compound other than vancomycin (standard). The active isolates from primary screening were heterogeneous in their overall macroscopic, biochemical, and physiological characteristics. The two potent isolates showing antibacterial activity were found to belong to different distinct taxonomic groups.

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