scholarly journals Research Progress on Antibacterial Activities and Mechanisms of Natural Alkaloids: A Review

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 318
Author(s):  
Yumei Yan ◽  
Xing Li ◽  
Chunhong Zhang ◽  
Lijuan Lv ◽  
Bing Gao ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Bacterial Resistance ◽  
Structural Diversity ◽  
Antibacterial Activities ◽  
Cell Membrane Permeability ◽  
Research Progress ◽  
Chemical Structures ◽  
Significant Research ◽  
New Type ◽  
Antibacterial Spectrum

Alkaloids are nitrogen-containing heterocyclic compounds typically isolated from plants. They represent one of the most important types of natural products because of their large number and structural diversity and complexity. Based on their chemical core structures, alkaloids are classified as isoquinolines, quinolines, indoles, piperidine alkaloids, etc. In-depth analyses of alkaloids have revealed their antibacterial activities. To date, due to the widespread use of antibiotics, the problem of drug-resistant bacterial infections has been gradually increasing, which severely affects the clinical efficacy of antibacterial therapies and patient safety. Therefore, significant research efforts are focused on alkaloids because they represent a potentially new type of natural antibiotic with a wide antibacterial spectrum, rare adverse reactions, and a low tendency to produce drug resistance. Their main antibacterial mechanisms include inhibition of bacterial cell wall synthesis, change in cell membrane permeability, inhibition of bacterial metabolism, and inhibition of nucleic acid and protein synthesis. This article reviews recent reports about the chemical structures and the antibacterial activities and mechanisms of alkaloids. The purpose is to solve the problem of bacterial resistance and to provide a certain theoretical basis and research ideas for the development of new antibacterial drugs.

scholarly journals Biotechnological Potential of Streptomyces Siderophores as New Antibiotics

2020 ◽  
Vol 27 ◽  
Author(s):  
Luciana Terra ◽  
Paul Dyson ◽  
Norman Ratcliffe ◽  
Helena Carla Castro ◽  
Ana Carolina Paulo Vicente
Keyword(s):  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Bacterial Resistance ◽  
Wide Spectrum ◽  
Gene Clusters ◽  
Bibliographic Databases ◽  
Genus Streptomyces ◽  
Chemical Structures ◽  
New Antibiotics ◽  
Potential Applications

Background: Siderophores are small molecule iron-chelators produced by microorganisms and plants growing mostly under low iron conditions. Siderophores allow iron capture and transport through cell membranes into the cytoplasm, where iron is released for use in biological processes. These bacterial iron uptake systems can be used for antibiotic conjugation or as targets for killing pathogenic bacteria. Siderophores have been explored recently because of their potential applications in environmental and therapeutic research. They are present in Streptomyces, Gram-positive bacteria that are an important source for discovering new siderophores. Objective: This review summarizes siderophore molecules produced by the genus Streptomyces emphasizing their potential as biotechnological producers and also illustrating genomic tools for discovering siderophores useful for treating bacterial infections. Methods: The literature search was performed using PUBMED and MEDLINE databases with keywords siderophore, secondary metabolites, Trojan horse strategy, sideromycin and Streptomyces. The literature research focused on bibliographic databases including all siderophores identified in the genus Streptomyces. In addition, reference genomes of Streptomyces from GenBank were used to identify siderophore biosynthetic gene clusters by using the antiSMASH platform. Results: This review has highlighted some of the many siderophore molecules produced by Streptomyces, illustrating the diversity of their chemical structures and wide spectrum of bioactivities against pathogenic bacteria. Furthermore, the possibility of using siderophores conjugated with antibiotics could be an alternative to overcome bacterial resistance to drugs and could improve their therapeutic efficacy. Conclusion: This review confirms the importance of Streptomyces as a rich source of siderophores, and underlines their potential as antibacterial agents.

Advances in Spirocyclic Hybrids: Chemistry and Medicinal Actions

2018 ◽  
Vol 25 (31) ◽  
pp. 3748-3767 ◽  
Author(s):  
Mohammed Benabdallah ◽  
Oualid Talhi ◽  
Fatiha Nouali ◽  
Nouredine Choukchou-Braham ◽  
Khaldoun Bachari ◽  
...  
Keyword(s):  
Anticancer Agents ◽  
Apoptotic Cell ◽  
Structural Diversity ◽  
Antibacterial Activities ◽  
Innovative Drug ◽  
Neuroprotective Effects ◽  
Cellular Division ◽  
Bioactive Natural Products ◽  
Anaplastic Lymphoma ◽  
Dna Binders

The present review deals with the progress in medicinal chemistry of spirocyclic compounds, a wider class of natural and synthetic organic molecules, defined as a hybrid of two molecular entities covalently linked via a unique tetrahedral carbon. This spiro central carbon confers to the molecules a tridimensional structurally oriented framework, which is found in many medicinally relevant compounds, a well-known example is the antihypertensive spironolactone. Various bioactive natural products possess the privileged spiro linkage and different chemo-types thereof become synthetically accessible since the 20th century. Actually, there has been a growing interest in the synthesis of heterocyclic hybrids gathered via a spiro carbon. Most of these combinations are two moieties in one scaffold being able to interfere with biological systems through sequential mechanisms. Spirocyclic hybrids containing indole or oxindole units are compounds exhibiting higher interaction with biological receptors by protein inhibition or enzymatic pathways and their recognition as promising anticancer agents in targeted chemotherapy is foreseen. These specific, low-weight and noncomplex spirocyclic hybrids are potent inhibitors of SIRT1, Mdm2–p53 and PLK4, showing affinity for anaplastic lymphoma kinase (ALK) receptor. They are also known as excellent DNA binders, acting on cellular division by arresting the cell cycle at different phases and inducing apoptotic cell death. A structural diversity of spirocyclic hybrids has proved neuroprotective effects, anti-HIV, antiviral and antibacterial activities. Hundred of papers are mentioned in this review underlying chemical issues and pharmacological potencies of spiro compounds, which render them impressive synthetic hits for innovative drug conception.

Synthesis and Antimicrobial activities of Some Polyphenol compounds by Nano ZnO-TBAB as a Heterogeneous Catalytic Media

2020 ◽  
Vol 17 ◽  
Author(s):  
Rahele Bargebid ◽  
Ali Khalafi-Nezhad ◽  
Kamiar Zomorodian ◽  
Leila Zamani ◽  
Ali Ahmadinejad ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
Antimicrobial Activities ◽  
Reusable Catalyst ◽  
Nano Zno ◽  
Antifungal Activities ◽  
Chemical Structures ◽  
Heterogeneous Catalytic ◽  
Solvent Free Conditions ◽  
New Compounds ◽  
Derivatives Of

Introduction: Mannich reaction is a typical example of a three-component condensation reaction and the chemistry of Mannich bases has been the matter of search by researchers. Here an efficient procedure for the synthesis of some new Mannich derivatives of simple phenols is described. Methods: In this procedure a microwave-assisted and solvent less condensation were done between different phenols, secondary amines and paraformaldehyde. The reactions proceed in the presence of catalytic amount of nano ZnO and tetrabutylammonium bromide (TBAB) in excellent yields. 10 new compounds were synthesized (A1-A10). Chemical structures of all new compounds were confirmed by different spectroscopic methods. We optimized the chemical reactions in different conditions. Optimization reactions were done in the presence of different mineral oxides, different amount of TBAB and also different solvents. Nano ZnO and TBAB in catalytic amounts and solvent free conditions were the best conditions. All the synthesized compounds were screened for their antimicrobial activities. Antifungal and antibacterial activities of the synthesized compounds were evaluated against some Candida, filaments fungi, gram positive and gram negative bacteria by broth micro dilution method as recommended by CLSI. Results: The result showed that compounds A2, A3 and A4 against most of the tested Candida species and compounds A5 and A7 against C. parapsilosis and C. tropicalis, exhibited considerable antifungal activities. Also Compounds A8 and A10 showed desirable antifungal activities against C. neoformance and C. parapsilosis, respectively. The antibacterial activities of the synthesized compounds were also evaluated. Compounds A6 - A10 against E. Fecalis and compounds A5, A7, A9 and A10 against P. aeruginosa showed desirable antibacterial activities. Discussion: We have synthesized some new Mannich adducts of poly-hydroxyl phenols in the presence of nano-ZnO as a reusable catalyst, with the hope of discovering new lead compounds serving as potent antimicrobial agents. The advantages of this method are generality, high yields with short reaction times, simplicity, low cost and matching with green chemistry protocols. The antimicriobial studies of Mannich derivatives of phenols showed desirable results in vitro.

scholarly journals In Vitro Characterization of the Antibacterial Spectrum of Novel Bacterial Type II Topoisomerase Inhibitors of the Aminobenzimidazole Class

2006 ◽  
Vol 50 (4) ◽  
pp. 1228-1237 ◽  
Author(s):  
Nagraj Mani ◽  
Christian H. Gross ◽  
Jonathan D. Parsons ◽  
Brian Hanzelka ◽  
Ute Müh ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
Wide Spectrum ◽  
Dna Gyrase ◽  
Antibacterial Activities ◽  
Mechanisms Of Action ◽  
Fluoroquinolone Resistance ◽  
Topoisomerase Iv ◽  
Low Frequencies

ABSTRACT Antibiotics with novel mechanisms of action are becoming increasingly important in the battle against bacterial resistance to all currently used classes of antibiotics. Bacterial DNA gyrase and topoisomerase IV (topoIV) are the familiar targets of fluoroquinolone and coumarin antibiotics. Here we present the characterization of two members of a new class of synthetic bacterial topoII ATPase inhibitors: VRT-125853 and VRT-752586. These aminobenzimidazole compounds were potent inhibitors of both DNA gyrase and topoIV and had excellent antibacterial activities against a wide spectrum of problematic pathogens responsible for both nosocomial and community-acquired infections, including staphylococci, streptococci, enterococci, and mycobacteria. Consistent with the novelty of their structures and mechanisms of action, antibacterial potency was unaffected by commonly encountered resistance phenotypes, including fluoroquinolone resistance. In time-kill assays, VRT-125853 and VRT-752586 were bactericidal against Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, and Haemophilus influenzae, causing 3-log reductions in viable cells within 24 h. Finally, similar to the fluoroquinolones, relatively low frequencies of spontaneous resistance to VRT-125853 and VRT-752586 were found, a property consistent with their in vitro dual-targeting activities.

Electromagnetic-launch-based method for cost-efficient space debris removal

2020 ◽  
Vol 29 (1) ◽  
pp. 94-106
Author(s):  
Chongyuan Hou ◽  
Yuan Yang ◽  
Yikang Yang ◽  
Kaizhong Yang ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Space Debris ◽  
Orbit Space ◽  
Low Earth Orbit ◽  
Research Progress ◽  
Area Of Interest ◽  
Electromagnetic Launch ◽  
Debris Removal ◽  
Significant Research ◽  
Electromagnetic Launcher ◽  
Cost Efficient

AbstractThe increase in space debris orbiting Earth is a critical problem for future space missions. Space debris removal has thus become an area of interest, and significant research progress is being made in this field. However, the exorbitant cost of space debris removal missions is a major concern for commercial space companies. We therefore propose the debris removal using electromagnetic launcher (DREL) system, a ground-based electromagnetic launch system (railgun), for space debris removal missions. The DREL system has three components: a ground-based electromagnetic launcher (GEML), suborbital vehicle (SOV), and mass of micrometer-scale dust (MSD) particles. The average cost of removing a piece of low-earth orbit space debris using DREL was found to be approximately USD 160,000. The DREL method is thus shown to be economical; the total cost to remove more than 2,000 pieces of debris in a cluster was only approximately USD 400 million, compared to the millions of dollars required to remove just one or two pieces of debris using a conventional space debris removal mission. By using DREL, the cost of entering space is negligible, thereby enabling countries to remove their space debris in an affordable manner.

scholarly journals Tackling Virulence of Pseudomonas aeruginosa by the Natural Furanone Sotolon

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 871
Author(s):  
Mohammed F. Aldawsari ◽  
El-Sayed Khafagy ◽  
Ahmed Al Saqr ◽  
Ahmed Alalaiwe ◽  
Hisham A. Abbas ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Bacterial Infections ◽  
Therapeutic Agent ◽  
Bacterial Resistance ◽  
Inhibitory Concentration ◽  
Bacterial Biofilm ◽  
Resistant Bacteria ◽  
Resistance Development

The bacterial resistance development due to the incessant administration of antibiotics has led to difficulty in their treatment. Natural adjuvant compounds can be co-administered to hinder the pathogenesis of resistant bacteria. Sotolon is the prevailing aromatic compound that gives fenugreek its typical smell. In the current work, the anti-virulence activities of sotolon on Pseudomonas aeruginosa have been evaluated. P. aeruginosa has been treated with sotolon at sub-minimum inhibitory concentration (MIC), and production of biofilm and other virulence factors were assessed. Moreover, the anti-quorum sensing (QS) activity of sotolon was in-silico evaluated by evaluating the affinity of sotolon to bind to QS receptors, and the expression of QS genes was measured in the presence of sotolon sub-MIC. Furthermore, the sotolon in-vivo capability to protect mice against P. aeruginosa was assessed. Significantly, sotolon decreased the production of bacterial biofilm and virulence factors, the expression of QS genes, and protected mice from P. aeruginosa. Conclusively, the plant natural substance sotolon attenuated the pathogenicity of P. aeruginosa, locating it as a plausible potential therapeutic agent for the treatment of its infections. Sotolon can be used in the treatment of bacterial infections as an alternative or adjuvant to antibiotics to combat their high resistance to antibiotics.

scholarly journals 1,3-Diketone Calix[4]arene Derivatives—A New Type of Versatile Ligands for Metal Complexes and Nanoparticles

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1214
Author(s):  
Sergey N. Podyachev ◽  
Rustem R. Zairov ◽  
Asiya R. Mustafina
Keyword(s):  
Structural Diversity ◽  
Building Blocks ◽  
Structural Features ◽  
Structure Property ◽  
One Pot ◽  
Arene Ligands ◽  
Structure Property Relationships ◽  
New Type ◽  
Synthetic Routes ◽  
Magnetic Resonance Imaging Mri

The present review is aimed at highlighting outlooks for cyclophanic 1,3-diketones as a new type of versatile ligands and building blocks of the nanomaterial for sensing and bioimaging. Thus, the main synthetic routes for achieving the structural diversity of cyclophanic 1,3-diketones are discussed. The structural diversity is demonstrated by variation of both cyclophanic backbones (calix[4]arene, calix[4]resorcinarene and thiacalix[4]arene) and embedding of different substituents onto lower or upper macrocyclic rims. The structural features of the cyclophanic 1,3-diketones are correlated with their ability to form lanthanide complexes exhibiting both lanthanide-centered luminescence and magnetic relaxivity parameters convenient for contrast effect in magnetic resonance imaging (MRI). The revealed structure–property relationships and the applicability of facile one-pot transformation of the complexes to hydrophilic nanoparticles demonstrates the advantages of 1,3-diketone calix[4]arene ligands and their complexes in developing of nanomaterials for sensing and bioimaging.

scholarly journals In VivoImpact of Met221 Substitution in GOB Metallo-β-Lactamase

2012 ◽  
Vol 56 (4) ◽  
pp. 1769-1773 ◽  
Author(s):  
Jorgelina Morán-Barrio ◽  
María-Natalia Lisa ◽  
Alejandro J. Vila
Keyword(s):  
Antibiotic Resistance ◽  
Protein Stability ◽  
Metal Binding ◽  
Active Sites ◽  
Bacterial Resistance ◽  
Structural Diversity ◽  
Hydrophobic Core

ABSTRACTMetallo-β-lactamases (MβLs) represent one of the main mechanisms of bacterial resistance against β-lactam antibiotics. The elucidation of their mechanism has been limited mostly by the structural diversity among their active sites. All MβLs structurally characterized so far present a Cys or a Ser residue at position 221, which is critical for catalysis. GOB lactamases stand as an exception within this picture, possessing a Met residue in this location. We studied different mutants in this position, and we show that Met221 is essential for protein stability, most likely due to its involvement in a hydrophobic core. In contrast to other known MβLs, residue 221 is not involved in metal binding or in catalysis in GOB enzymes, further highlighting the structural diversity of MβLs. We also demonstrate the usefulness of protein periplasmic profiles to assess the contribution of protein stability to antibiotic resistance.

scholarly journals From Residues to Added-Value Bacterial Biopolymers as Nanomaterials for Biomedical Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1492
Author(s):  
Francisco G. Blanco ◽  
Natalia Hernández ◽  
Virginia Rivero-Buceta ◽  
Beatriz Maestro ◽  
Jesús M. Sanz ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Carbon Sources ◽  
Structural Diversity ◽  
Added Value ◽  
Nanoscale Systems ◽  
Chemical Structures ◽  
Wide Range ◽  
Peptide Functionalization ◽  
Metabolic Strategies ◽  
Drug Nanocarriers

Bacterial biopolymers are naturally occurring materials comprising a wide range of molecules with diverse chemical structures that can be produced from renewable sources following the principles of the circular economy. Over the last decades, they have gained substantial interest in the biomedical field as drug nanocarriers, implantable material coatings, and tissue-regeneration scaffolds or membranes due to their inherent biocompatibility, biodegradability into nonhazardous disintegration products, and their mechanical properties, which are similar to those of human tissues. The present review focuses upon three technologically advanced bacterial biopolymers, namely, bacterial cellulose (BC), polyhydroxyalkanoates (PHA), and γ-polyglutamic acid (PGA), as models of different carbon-backbone structures (polysaccharides, polyesters, and polyamides) produced by bacteria that are suitable for biomedical applications in nanoscale systems. This selection models evidence of the wide versatility of microorganisms to generate biopolymers by diverse metabolic strategies. We highlight the suitability for applied sustainable bioprocesses for the production of BC, PHA, and PGA based on renewable carbon sources and the singularity of each process driven by bacterial machinery. The inherent properties of each polymer can be fine-tuned by means of chemical and biotechnological approaches, such as metabolic engineering and peptide functionalization, to further expand their structural diversity and their applicability as nanomaterials in biomedicine.

Efficient Synthesis of Novel N-[4-Methyl-3-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)thiazol-2(3H)-ylidene]benzamide Hybrid Ring System as Potential Antibacterial Agents

2021 ◽  
Vol 17 ◽  
Author(s):  
Hummera Rafique ◽  
Aamer Saeed ◽  
Muhammad Naseem ◽  
Tauqeer Riaz ◽  
Fouzia Perveen ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
Antioxidant Activities ◽  
Antibacterial Properties ◽  
Antibacterial Activities ◽  
Structural Features ◽  
Ring System ◽  
Biologically Active ◽  
Thiazole Ring ◽  
Spectroscopic Techniques ◽  
Hybrid Ring

Background: Heterocyclic compounds display versatile biological applications, so the aim of this paper was to prepare biologically important heterocycles with enhanced bacterial resistance and to evaluate for their various structural features that are responsible for their biological properties. Objective: The objective was to synthesize bacterial resistance compounds with enhanced antibacterial properties. Method: Ester moiety containing thiazole ring was converted into its hydrazide derivatives. These heterocyclic derivatives were cyclized into another ring oxadiazole; hence a hybrid ring system of two biologically active rings was prepared. Result: All the synthesized compounds were characterized by spectroscopic techniques and were screened for their antibacterial potential; they possess significant antibacterial activities. Conclusion: New hybrid heterocyclic ring systems were synthesized by cyclization of hydrazide derivatives by adopting two step strategy in good yields. All the synthesized compounds were evaluated for their antioxidant activities; they showed moderate to significant activities. QSAR and Molecular docking studies were performed to determine the mode of interaction. Experimental and computational data is in accordance with the determined antibacterial activities.

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