scholarly journals Silver (I) N-Heterocyclic Carbene Complexes: A Winning and Broad Spectrum of Antimicrobial Properties

2021 ◽  
Vol 22 (5) ◽  
pp. 2497
Author(s):  
Filippo Prencipe ◽  
Anna Zanfardino ◽  
Michela Di Napoli ◽  
Filomena Rossi ◽  
Stefano D’Errico ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Antimicrobial Properties ◽  
Resistance Mechanisms ◽  
Heterocyclic Carbenes ◽  
Significant Activity ◽  
Bacterial Strains ◽  
Development Of Resistance ◽  
Starting Point ◽  
Catalytic Chemistry

The evolution of antibacterial resistance has arisen as the main downside in fighting bacterial infections pushing researchers to develop novel, more potent and multimodal alternative drugs.Silver and its complexes have long been used as antimicrobial agents in medicine due to the lack of silver resistance and the effectiveness at low concentration as well as to their low toxicities compared to the most commonly used antibiotics. N-Heterocyclic Carbenes (NHCs) have been extensively employed to coordinate transition metals mainly for catalytic chemistry. However, more recently, NHC ligands have been applied as carrier molecules for metals in anticancer applications. In the present study we selected from literature two NHC-carbene based on acridinescaffoldand detailed nonclassicalpyrazole derived mono NHC-Ag neutral and bis NHC-Ag cationic complexes. Their inhibitor effect on bacterial strains Gram-negative and positivewas evaluated. Imidazolium NHC silver complex containing the acridine chromophore showed effectiveness at extremely low MIC values. Although pyrazole NHC silver complexes are less active than the acridine NHC-silver, they represent the first example of this class of compounds with antimicrobial properties. Moreover all complexesare not toxic and they show not significant activity againstmammalian cells (Hek lines) after 4 and 24 h. Based on our experimental evidence, we are confident that this promising class of complexes could represent a valuable starting point for developing candidates for the treatment of bacterial infections, delivering great effectiveness and avoiding the development of resistance mechanisms.

scholarly journals PROPAGATION OF ANTIMICROBIAL RESISTANT Salmonella spp. IN BIVALVE MOLLUSKS FROM ESTUARY AREAS OF BAHIA, BRAZIL

2016 ◽  
Vol 29 (2) ◽  
pp. 450-457 ◽  
Author(s):  
CARLA SILVA DA SILVEIRA ◽  
OSCARINA VIANA DE SOUSA ◽  
NORMA SUELY EVANGELISTA-BARRETO
Keyword(s):  
Nalidixic Acid ◽  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Antimicrobial Agents ◽  
Resistance Index ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Bivalve Mollusks ◽  
Salmonella Spp ◽  
Development Of Resistance

ABSTRACT: In recent years, the emergence of resistant pathogens has complicated the treatment of bacterial infections in livestock production as well as in the medical field, due to the development of resistance mechanisms by microorganisms. The objective of this study was to delineate the antimicrobial resistance profile of Salmonella spp. strains isolated from bivalve mollusks (oysters and mussels) and from estuarine environment water of two regions of Bahia, Brazil. Twenty-seven strains, 12 isolated from bivalve mollusks and 15 from estuarine water, were tested. Eight antimicrobial agents (phenicol, beta-lactams, tetracyclines, quinolones and fluoroquinolones classes) were used for a susceptibility test, Minimum Inhibitory Concentration (MIC) and extended-spectrum beta-lactamases (ESBLs) production. Isolates showed high susceptibility to the classes of antimicrobial agents tested, with resistance only to nalidixic acid (27%), ampicillin (25%) and tetracycline (25%). Bacterial resistance was of chromosomal origin and the multidrug resistance index (MAR) among isolates of shellfish (mussels in natura) was 0.25. The MIC was found to be 100 µg/mL, 500 µg/mL and 350 µg/mL to nalidixic acid, ampicillin and tetracycline, respectively. None of the isolates presented ESBLs production. The presence of multidrug-resistant and high MIC Salmonella spp. is being conveyed in extraction areas of bivalve mollusks in the State of Bahia, Brazil.

STUDIES ON SOME BACTERIAL DISEASES IN OREOCHROMIS NILOTICUS WITH SPECIAL REFERENCES TO TREATMENT

2018 ◽  
pp. 39-47
Author(s):  
Viola Zaki ◽  
Ahmed EL-gamal ◽  
Yasmin Reyad
Keyword(s):  
Oreochromis Niloticus ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Histopathological Examination ◽  
Klebsiella Oxytoca ◽  
Bacterial Isolates ◽  
Bacterial Strains ◽  
Tissue Samples ◽  
Hydropic Degeneration ◽  
Total Prevalence

he present research carried out to study the common bacterial infections in Oreochromis niloticus (Nile tilapia) in Manzala area at Dakahlia governorate and possible antimicrobial agents used for treatment. A total number of 400 fish were randomly collected from Manzala private farms at Dakahlia governorate and subjected to the clinical, bacteriological and histopathological examination. The highest prevalence of bacterial isolates during the whole period of examination of naturally infected O.niloticus was recorded for A.hydrophila (22.66%), followed by V.alginolyticus (19.01%), V.parahemolyticus (13.80%), Streptococcus spp. (12.24%), A.caviae (11.72%), V.cholera (10.16%), A.salmonicida (7.55%), while the lowest prevalence was recorded for Klebsiella oxytoca (2.86%). The seasonal highest total prevalence of bacterial isolates from examined naturally infected O. niloticus was recorded in spring (30.21%), followed by autumn (28.39%), then summer (22.40%) and the lowest prevalence was recorded in winter (19.01%). Histopathological findings of the tissue samples which collected from different organs of naturally infected O.niloticus revealed that spleen show marked hemosiderosis and sever hemorrhage, gills showsever congestion of lamellar capillaries with marked aneurysm, necrosis and hemorrhage of lamellar epithelium and liver show sever hydropic degeneration and necrosis of hepatocytes, Ciprofloxacin was the most effective antibiotic against all isolated bacterial strains

Antimicrobial properties of actively purified secondary metabolites isolated from different marine organisms

2020 ◽  
Vol 21 ◽  
Author(s):  
Nilushi Indika Bamunu Arachchige ◽  
Fazlurrahman Khan ◽  
Young-Mog Kim
Keyword(s):  
Secondary Metabolites ◽  
Pathogenic Bacteria ◽  
Antimicrobial Agents ◽  
Bacterial Species ◽  
Antimicrobial Properties ◽  
Antimicrobial Effect ◽  
Cost Effective ◽  
Resistance Mechanisms ◽  
Marine Organisms ◽  
Antimicrobial Compounds

Background: The treatment of infection caused by pathogenic bacteria becomes one of the serious concerns globally. The failure in the treatment was found due to the exhibition of multiple resistance mechanisms against the antimicrobial agents. Emergence of resistant bacterial species has also been observed due to prolong treatment using conventional antibiotics. To combat these problems, several alternative strategies have been employed using biological and chemically synthesized compounds as antibacterial agents. Marine organisms considered as one of the potential sources for the isolation of bioactive compounds due to the easily available, cost-effective, and eco-friendly. Methods: The online search methodology was adapted for the collection of information related to the antimicrobial properties of marine-derived compounds. These compound has been isolated and purified by different purification techniques, and their structure also characterized. Furthermore, the antibacterial activities have been reported by using broth microdilution as well as disc diffusion assays. Results: The present review paper describes the antimicrobial effect of diverse secondary metabolites which are isolated and purified from the different marine organisms. The structural elucidation of each secondary metabolite has also been done in the present paper, which will help for the in silico designing of the novel and potent antimicrobial compounds. Conclusion: A thorough literature search has been made and summarizes the list of antimicrobial compounds that are isolated from both prokaryotic and eukaryotic marine organisms. The information obtained from the present paper will be helpful for the application of marine compounds as antimicrobial agents against different antibiotic-resistant human pathogenic bacteria.

Development of Peptides that Inhibit Aminoglycoside-Modifying Enzymes and β-Lactamases for Control of Resistant Bacteria

2020 ◽  
Vol 21 (10) ◽  
pp. 1011-1026
Author(s):  
Bruna O. Costa ◽  
Marlon H. Cardoso ◽  
Octávio L. Franco
Keyword(s):  
Drug Target ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Treatment Strategies ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Specific Chemical ◽  
Target Interaction ◽  
Multiresistant Bacteria ◽  
Acute Bacterial Infections

: Aminoglycosides and β-lactams are the most commonly used antimicrobial agents in clinical practice. This occurs because they are capable of acting in the treatment of acute bacterial infections. However, the effectiveness of antibiotics has been constantly threatened due to bacterial pathogens producing resistance enzymes. Among them, the aminoglycoside-modifying enzymes (AMEs) and β-lactamase enzymes are the most frequently reported resistance mechanisms. AMEs can inactivate aminoglycosides by adding specific chemical molecules in the compound, whereas β-lactamases hydrolyze the β-lactams ring, preventing drug-target interaction. Thus, these enzymes provide a scenario of multidrug-resistance and a significant threat to public health at a global level. In response to this challenge, in recent decades, several studies have focused on the development of inhibitors that can restore aminoglycosides and β-lactams activity. In this context, peptides appear as a promising approach in the field of inhibitors for future antibacterial therapies, as multiresistant bacteria may be susceptible to these molecules. Therefore, this review focused on the most recent findings related to peptide-based inhibitors that act on AMEs and β-lactamases, and how these molecules could be used for future treatment strategies.

scholarly journals Synthesis and Antimicrobial Properties of Highly Cross-Linked pH-Sensitive Hydrogels through Gamma Radiation

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2223
Author(s):  
Moises Bustamante-Torres ◽  
Victor H. Pino-Ramos ◽  
David Romero-Fierro ◽  
Sandra P. Hidalgo-Bonilla ◽  
Héctor Magaña ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Film Formation ◽  
Antimicrobial Properties ◽  
Ph Sensitive ◽  
Scanning Calorimetry ◽  
Polymeric Systems ◽  
E Coli ◽  
High Prevalence

The design of new polymeric systems for antimicrobial drug release focused on medical/surgical procedures is of great interest in the biomedical area due to the high prevalence of bacterial infections in patients with wounds or burns. For this reason, in this work, we present a new design of pH-sensitive hydrogels copolymerized by a graft polymerization method (gamma rays), intended for localized prophylactic release of ciprofloxacin and silver nanoparticles (AgNPs) for potential topical bacterial infections. The synthesized hydrogels were copolymerized from acrylic acid (AAc) and agar. Cross-linked hydrogel film formation depended on monomer concentrations and the degree of radiation used (Cobalt-60). The obtained hydrogel films were characterized by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical testing. The swelling of the hydrogels was evidenced by the influence of their pH-sensitiveness. The hydrogel was loaded with antimicrobial agents (AgNPs or ciprofloxacin), and their related activity was evaluated. Finally, the antimicrobial activity of biocidal-loaded hydrogel was tested against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) on in vitro conditions.

Coumarin-1,2,3-triazole Hybrid Molecules: An Emerging Scaffold for Combating Drug Resistance

2021 ◽  
Vol 21 ◽  
Author(s):  
Harish C. Upadhyay
Keyword(s):  
Drug Resistance ◽  
Antimicrobial Agents ◽  
Plant Secondary Metabolites ◽  
Cost Effective ◽  
Resistance Mechanisms ◽  
Biologically Active ◽  
Multidrug Therapy ◽  
Diverse Range ◽  
Development Of Resistance ◽  
Hybrid Molecules

: No doubt antibiotics have saved billions of lives, but lack of novel antibiotics, development of resistance mechanisms in almost all clinical isolates of bacteria, and recurrent infections caused by persistent bacteria hamper the successful treatment of infections. Due to widespread emergence of resistance, even the new families of antimicrobial agents have a short life expectancy. Drugs acting on single target often lead to drug resistance and are associated with various side effects. To overcome this problem either multidrug therapy or single drug acting on multiple targets may be used. The later are called ‘hybrid molecules’ which are formed by clubbing two biologically active pharmacophores together with or without an appropriate linker. In this rapidly evolving era, the development of natural product-based hybrid molecules may be a super-alternative to multidrug therapy to combat drug resistance caused by various bacterial and fungal strains. Coumarins (benzopyran-2-one) are one of the earliest reported plant secondary metabolites having clinically proven diverse range of pharmacological properties. On the other hand, 1,2,3-triazole is a common pharmacophore in many drugs responsible for polar interactions improving the solubility and binding affinity to biomolecular targets. In this review we discuss recent advances in Coumarin-1,2,3-triazole hybrids as potential antibacterial agents aiming to provide a useful platform for the exploration of new leads with broader spectrum, more effectiveness, less toxicity with multiple modes of action for the development of cost-effective and safer drugs in the future.

scholarly journals Chemically modified polystyrene co-loaded with antimicrobial agents

2021 ◽  
Vol 2120 (1) ◽  
pp. 012012
Author(s):  
Y X Koh ◽  
H L Choo ◽  
Y H Wong ◽  
C H Yeong
Keyword(s):  
Antimicrobial Agent ◽  
Antimicrobial Agents ◽  
Antimicrobial Properties ◽  
Silver Ions ◽  
Exchange Capacity ◽  
Secondary Process ◽  
Ionic Exchange ◽  
Bacterial Strains ◽  
Surgical Guides ◽  
Antimicrobial Material

Abstract A recent study showed that at least 50% of nosocomial infections are due to medical indwelling devices like surgical guides and prosthetics. This amounts to about 2 million patients affected a year. The reason for such statistics is the growth of microorganisms on the surfaces of the medical devices. There have been many attempts to create antimicrobial materials but most materials are unable to hold more than one antimicrobial agent without a secondary process. The study related to antimicrobial material with more than one type of agent is rarely found in literature. Hence, the objective of this project is to produce an antimicrobial material that can hold more than one antimicrobial agent without the need for a secondary process. The material is produced by sulfonating high impact polystyrene (HIPS) and attaching copper and silver ions. The optimum time of sulfonation of the HIPS was determined by the degree of sulfonation and ion exchange capacity. Then, the sulfonated HIPS were loaded with both copper and silver ions at different ratios. The 6-hour sample yielded the highest degree of sulfonation and ionic exchange capacity of 33.7% and 2.57 meq/g, respectively. In future work, the characterization of the 6-hour sulfonated HIPS sample loaded with copper and silver ions at different concentration ratios will be performed using TGA, DSC and FTIR spectroscopy. Lastly, the efficacy of the antimicrobial properties of the sulfonated HIPS will be tested using different bacterial strains.

scholarly journals Investigation of the Biochemical and Ultrastructural Mechanisms Underlying the Antimicrobial Activity of Mimusops spp. Extracts

2020 ◽  
Vol 17 (2) ◽  
pp. 0452
Author(s):  
Mahmoud S.M. Mohamed ◽  
Gehad Abdelmohsen ◽  
Gouda T. M. Dawoud
Keyword(s):  
Bacterial Infections ◽  
High Performance ◽  
Antimicrobial Agents ◽  
Antimicrobial Effect ◽  
Inhibition Zone ◽  
Antibacterial Activities ◽  
Ultrastructural Changes ◽  
Bacterial Strains ◽  
Leaf Extracts ◽  
Traditional Medicines

Antibiotic resistance is the major growing threat facing the pharmacological treatment of bacterial infections. Therefore, bioprospecting the medicinal plants could provide potential sources for antimicrobial agents. Mimusops, the biggest and widely distributed plant genus of family Sapotaceae, is used in traditional medicines due to its promising pharmacological activities. This study was conducted to elucidate the antimicrobial effect of three unexplored Mimusops spp. (M. kummel, M. laurifolia and M. zeyheri). Furthermore, the mechanisms underlying such antibacterial activity were studied. The Mimusops leaf extracts revealed significant antibacterial activities against the five tested bacterial strains with a maximum inhibition zone diameter of 22.0 mm against B. subtilis compared with standard antibiotic ciprofloxacin. The minimal inhibitory and bactericidal concentration values against tested Gram-positive and Gram-negative bacterial strains ranged from 3.15-12.5 µg/ml. However, weak antifungal effect was recorded against Candida albicans with MIC value ˃25 µg/ml. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay showed that M. caffra was the best antioxidant (IC50=14.75±0.028 µg/ml), while M. laurifolia was the least one (IC50=34.22±0.014 µg/ml). The phenolics in plant leaves extracts were identified and quantified by high performance liquid chromatography (HPLC) which revealed the presence of seven phenolic acids and four flavonoids. The abundant phenolic compounds were rutin (5.216±0.067 mg/g dried wt.) and gallic acid (0.296±0.068 mg/g) followed by myricetin (0.317±0.091 mg/g) then kaempferol (0.113±0.049 mg/g) as flavonoids. The antibacterial mechanism of M. laurifolia extract, as a representative species, induces ultrastructural changes in the model bacterium Staphylococcus aureus with cell wall and plasma membrane lysis as revealed by transmission electron microscopy. Overall, Mimusops species (M. laurifolia, M. kummel and M. zeyheri) are promising natural alternative sources for antimicrobial agents.

Chemical Composition and Antimicrobial Activity of Teucrium Capitatum L. Subsp. Lusitanicum (Schreb.) T. Navarro & Rosua Essential Oil

2020 ◽  
Author(s):  
Haïfa Debbabi ◽  
Ridha El Mokni ◽  
Ibrahim Jlassi ◽  
Rajesh K Joshi ◽  
Saoussen Hammami
Keyword(s):  
Antimicrobial Activity ◽  
Chemical Composition ◽  
Essential Oil ◽  
Antimicrobial Properties ◽  
Significant Activity ◽  
Bacterial Strains ◽  
Gram Positive Bacteria ◽  
Sesquiterpene Hydrocarbons ◽  
Germacrene D

Abstract Chemical composition and antimicrobial activity of Teucrium capitatum L. subsp. lusitanicum essential oil was investigated for the first time in the present study. Qualitative and quantitative analyses of the chemical composition by gas chromatography and mass spectrometry (GC–FID and GC–MS) revealed the presence of 60 compounds representing 97.6% of the whole constituents. The main compounds were germacrene D (47.1%), spathulenol (5.8%), α-selinene (5.3%), germacrene A (2.9%), δ-cadinene (2.8%) and cubenol (2.7%). In vitro, the antimicrobial activity was investigated against five bacterial strains along with the yeast Candida albicans using broth microdilution assay. T. capitatum subsp. lusitanicum essential oil showed significant activity against the gram-positive bacteria Staphylococcus aureus (MIC = MBC = 78 μg mL−1), Bacillus subtilis (MIC = MBC = 156 μg mL−1) and the yeast C. albicans (MIC = MFC = 156 μg mL−1). The great potential of antimicrobial effects is most likely due to the very high percentage of sesquiterpene hydrocarbons particularly to germacrene D, for which the antimicrobial properties have been previously reported.

Synthesis, Antimicrobial Evaluation and In silico Studies of Novel 2,4- disubstituted-1,3-thiazole Derivatives

2018 ◽  
Vol 16 (2) ◽  
pp. 160-173 ◽  
Author(s):  
Mir Mohammad Masood ◽  
Mohammad Irfan ◽  
Shadab Alam ◽  
Phool Hasan ◽  
Aarfa Queen ◽  
...  
Keyword(s):  
In Silico ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Docking Studies ◽  
Bacterial Strains ◽  
Thiazole Derivatives ◽  
Standard Drug ◽  
Hek 293 ◽  
In Silico Studies

Background: 2,4-disubstituted-1,3-thiazole derivatives (2a–j), (3a–f) and (4a–f) were synthesized, characterized and screened for their potential as antimicrobial agents. In the preliminary screening against a panel of bacterial strains, nine compounds showed moderate to potent antibacterial activity (IC50 = 13.7-90.8 μg/ml). </P><P> Methods: In the antifungal screening, compound (4c) displayed potent antifungal activity (IC50 = 26.5 &#181;g/ml) against Candida tropicalis comparable to the standard drug, fluconazole (IC50 = 10.5 &#181;g/ml). Based on in vitro antimicrobial results, compounds 2f, 4c and 4e were selected for further pharmacological investigations. Hemolytic activity using human red blood cells (hRBCs) and cytotoxicity by MTT assay on human embryonic kidney (HEK-293) cells revealed non-toxic nature of the selected compounds (2f, 4c and 4e). To ascertain their possible mode of action, docking studies with the lead inhibitors (2f, 4c and 4e) were performed using crystal structure coordinates of bacterial methionine aminopeptidases (MetAPs), an enzyme involved in bacterial protein synthesis and maturation. Results: The results of in vitro and in silico studies provide a rationale for selected compounds (2f, 4c and 4e) to be carried forward for further structural modifications and structure-activity relationship (SAR) studies against these bacterial infections. Conclusion: The study suggested binding with one or more key amino acid residues in the active site of Streptococcus pneumoniae MetAP (SpMetAP) and Escherichia coli MetAP (EcMetAP). In silico physicochemical properties using QikProp confirmed their drug likeliness.

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