Quorum Sensing Inhibition in Chromobacterium violaceum, Antibacterial Activity and GC-MS Analysis of Centaurea praecox (Oliv. & Hiern) Extracts

The quorum sensing (QS) mechanism has become a viable research strategy for the discovery of plant-derived anti-virulent agents to control drug-resistant bacteria. The increasing incidences of drug-resistant bacteria and the effort to curb it necessitate this study. We investigated the QS inhibitory potential of Centaurea praecox extracts on Chromobacterium violaceum (CV), antibacterial activity, and determination of chemical composition using GC-MS. C. praecox was subjected to sequential extraction using hexane (HEX), dichloromethane (DCM), ethyl acetate (EA), ethanol (ET), and aqueous (AQ) solvents. The extracts were subsequently evaluated for antibacterial activity using disc diffusion and QS violacein inhibition using spectrophotometry. The antibacterial effects of the extracts were moderate on gram-positive bacteria at 4 mg/mL in the order: HEX >EA >DCM >ET =AQ. However, the DCM extract demonstrated the most effective violacein inhibition of ≥80% at 0.3 mg/mL. QS violacein inhibitions were generally found to be concentration-dependent in the order: DCM >EA >HEX >ET =AQ with efficacies of ≥ 90% inhibition at ≥ 0.6 mg/mL. GC-MS analysis on the most potent DCM extract revealed N-vinylmethanimine, N-ethyl formamide, and propanamide among components identified. We concluded that C. praecox DCM extract contains bioactive chemicals as QS inhibitors and potential anti-virulent agents capable of combating the pathogenicity of drug-resistant bacteria in vivo.

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GC-MS Analysis and Antibacterial Effects of Vernonia glaberrima n-Hexane Extracts alone and in Combination with Standard Antibiotics

Journal of Chemical Society of Nigeria ◽

10.46602/jcsn.v46i2.593 ◽

2021 ◽

Vol 46 (2) ◽

Author(s):

P. Gangas ◽

A.B. Aliyu ◽

A.O. Oyewale

Keyword(s):

Antibacterial Activity ◽

Antibacterial Activities ◽

Fatty Acid Esters ◽

Gas Chromatography Mass Spectrometry ◽

Resistant Bacteria ◽

Drug Resistant ◽

Ms Analysis ◽

Drug Resistant Bacteria ◽

Hexane Extracts

The occurrence of drug resistant bacteria warrant investigation on herbal plants for effective antibacterial agents. Vernonia glaberrima leaf (VGL) and stem (VGS) hexane extracts were subjected to analysis by gas chromatography-mass spectrometry (GC-MS) and subsequently evaluated for antibacterial activity alone and in combination each with Sparfloxacin (SPX) and Ciprofloxacin (CPX) on selected bacteria including resistant species. GC-MS analysis revealed fatty acid esters, triterpenoids and aromatic derivatives largely identified as responsible for the broad-spectrum antibacterial activity. Both the VGL and VGS demonstrated potent antibacterial activities on P. aeruginosa (29 mm and 27 mm), respectively. However, combination of SPX with VGL potentiated the effects on E. coli and S. typhi by synergistic interaction. Similarly, the efficacy of CFX in combination with VGS on MRSA (30 mm) was significantly enhanced by additive action. It was observed that VGS potentiation of CFX on P. aeruginosa (32 mm) was the most effective antibacterial inhibition recorded in the study. Thus, combination of SPX and CFX each with the extracts has revealed remarkable properties for alternative or complementary therapeutic strategy. Our findings elicit enormous potentials of V. glaberrima hexane extracts as treatment adjuncts for combating drug resistant bacteria. It will be interesting to evaluate in vivo effects of extracts in combination with antibiotics against drug resistant bacteria.

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Novel Seleno- and Thio-Urea Containing Dihydropyrrol-2-One Analogues as Antibacterial Agents

Antibiotics ◽

10.3390/antibiotics10030321 ◽

2021 ◽

Vol 10 (3) ◽

pp. 321

Author(s):

Shekh Sabir ◽

Tsz Tin Yu ◽

Rajesh Kuppusamy ◽

Basmah Almohaywi ◽

George Iskander ◽

...

Keyword(s):

Antibacterial Activity ◽

Antibiotic Resistance ◽

Quorum Sensing ◽

Antibacterial Agents ◽

Inhibitory Concentration ◽

Resistant Bacteria ◽

Drug Resistant ◽

Positive Bacterium ◽

Quorum Sensing Inhibition ◽

Drug Resistant Bacteria

The quorum sensing (QS) system in multi-drug-resistant bacteria such as P. aeruginosa is primarily responsible for the development of antibiotic resistance and is considered an attractive target for antimicrobial drug discovery. In this study, we synthesised a series of novel selenourea and thiourea-containing dihydropyrrol-2-one (DHP) analogues as LasR antagonists. The selenium DHP derivatives displayed significantly better quorum-sensing inhibition (QSI) activities than the corresponding sulphur analogues. The most potent analogue 3e efficiently inhibited the las QS system by 81% at 125 µM and 53% at 31 µM. Additionally, all the compounds were screened for their minimum inhibitory concentration (MIC) against the Gram-positive bacterium S. aureus, and interestingly, only the selenium analogues showed antibacterial activity, with 3c and 3e being the most potent with a MIC of 15.6 µM.

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Synergistic Antibacterial Activity of Lantana camara L., Parthenium hysterophorus L., Cannabis sativa L. and Justicia adhatoda L. Leaves Extract against Procured Multi-drug Resistant Bacteria In Vitro

European Journal of Medicinal Plants ◽

10.9734/ejmp/2021/v32i330379 ◽

2021 ◽

pp. 34-40

Author(s):

Jyoti Chandola ◽

Pooja Singh ◽

Rishabh Garg ◽

Narotam Sharma

Keyword(s):

Antibacterial Activity ◽

Medicinal Plants ◽

Cannabis Sativa ◽

Lantana Camara ◽

Parthenium Hysterophorus ◽

Resistant Bacteria ◽

Drug Resistant ◽

Drug Resistant Bacteria ◽

Weed Plants ◽

Justicia Adhatoda

The scientific study of this research has been focused on synergistic antibacterial activity of two weed plants, Lantana camara L., Parthenium hysterophorus L. alongwith two medicinal plants, Cannabis sativa L., Justicia adhatoda L. against multi- drug resistant (MDR) bacteria. Dried leaf powders of the plants were extracted using air-dried method followed by the ethanol- solvent extraction method for the crude extract of the leaves. The crude extracts were tested for antibacterial activity against three MDR bacteria, that is, one Gram positive bacteria- Staphylococcus aureus and two Gram negative bacteria- Escherichia coli and Proteus mirabilis. Out of 18 antibiotics tested against procured bacteria, Staphylococcus aureus was resistant to 10 out of 10 tested antibiotics, Escherichia coli was resistant to 4 out of 12 tested antibiotics and Proteus mirabilis was resistant to 9 out of 10 tested antibiotics. The tested weed plants and the medicinal plants when combined together showed more zone of inhibition against multidrug resistant bacteria ( Two combinations of phytochemicals Lantana camara, Cannabis sativa and Lantana camara, Cannabis sativa, Justicia adhatoda, Parthenium hysterophorus showed maximum zones of inhibition, that is, 30 mm) as compared to when these plants were tested solitarily, showing pronounced antibacterial activity. These findings showed that the antibacterial activity enhanced when they were combined together and this potential could be used against various infectious diseases with more research and modification in this area. Weed plants also holds as much importance as the medicinal plants although not to that extent, but they clearly inhibit the growth of bacteria and this property of weeds along with the medicinal plants holds a promising future in treating many diseases caused by multi-drug resistant bacteria on the pharmaceutical level.

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Nanoparticles Enable Efficient Delivery of Antimicrobial Peptides for the Treatment of Deep Infections

BIO Integration ◽

10.15212/bioi-2021-0003 ◽

2021 ◽

Author(s):

Yingxue Deng ◽

Rui Huang ◽

Songyin Huang ◽

Menghua Xiong

Keyword(s):

Antimicrobial Peptides ◽

Broad Spectrum ◽

Antimicrobial Properties ◽

Therapeutic Index ◽

Resistant Bacteria ◽

Drug Resistant ◽

Drug Resistant Bacteria ◽

Efficient Delivery ◽

Delivery Vehicles

Antimicrobial peptides (AMPs) have emerged as promising alternatives of traditional antibiotics against drug-resistant bacteria owing to their broad-spectrum antimicrobial properties and low tendency to drugresistance. However, their therapeutic efficacy in vivo, especially for infections in deep organs, is limited owing to their systemic toxicity and low bioavailability. Nanoparticles-based delivery systems offer a strategy to increase the therapeutic index of AMPs by preventing proteolysis, increasing the accumulation at infection sites, and reducing toxicity. Herein, we will discuss the current progress of using nanoparticles as delivery vehicles for AMPs for the treatment of deep infections.

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Vacancy‐Induced Antibacterial Activity of XS 2– y Quantum Dots against Drug‐Resistant Bacteria for Treatment of Bacterial Keratitis

Small ◽

10.1002/smll.202004677 ◽

2020 ◽

Vol 16 (42) ◽

pp. 2004677

Author(s):

Huiyuan Li ◽

Xiao Wang ◽

Xiaofei Zhao ◽

Guanhua Li ◽

Fengyan Pei ◽

...

Keyword(s):

Quantum Dots ◽

Antibacterial Activity ◽

Resistant Bacteria ◽

Bacterial Keratitis ◽

Drug Resistant ◽

Drug Resistant Bacteria

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Design, Engineering and Discovery of Novel α-Helical and β-Boomerang Antimicrobial Peptides against Drug Resistant Bacteria

International Journal of Molecular Sciences ◽

10.3390/ijms21165773 ◽

2020 ◽

Vol 21 (16) ◽

pp. 5773 ◽

Cited By ~ 7

Author(s):

Surajit Bhattacharjya ◽

Suzana K. Straus

Keyword(s):

Antimicrobial Peptides ◽

Resistant Bacteria ◽

Drug Resistant ◽

Antibiotic Development ◽

Extensively Drug Resistant ◽

Drug Resistant Bacteria ◽

Drying Up ◽

Further Development ◽

Lps Binding

In an era where the pipeline of new antibiotic development is drying up, the continuous rise of multi-drug resistant (MDR) and extensively drug resistant (XDR) bacteria are genuine threats to human health. Although antimicrobial peptides (AMPs) may serve as promising leads against drug resistant bacteria, only a few AMPs are in advanced clinical trials. The limitations of AMPs, namely their low in vivo activity, toxicity, and poor bioavailability, need to be addressed. Here, we review engineering of frog derived short α-helical AMPs (aurein, temporins) and lipopolysaccharide (LPS) binding designed β-boomerang AMPs for further development. The discovery of novel cell selective AMPs from the human proprotein convertase furin is also discussed.

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Developing an antibiotic effective against multi-drug resistant bacteria.

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314092857 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C714-C714

Author(s):

Calvin Steussy ◽

Cynthia Stauffacher ◽

Mark Lipton ◽

Mohamed Seleem

Keyword(s):

Pathogenic Bacteria ◽

Modern Medicine ◽

In Vivo Studies ◽

Resistant Bacteria ◽

Drug Resistant ◽

Lead Compound ◽

Drug Resistant Bacteria ◽

Coa Reductase

The emergence of multi-drug resistant pathogenic bacteria is one of the great challenges to modern medicine. The gram positive cocci Methicillin Resistant Staphylococcus aureus (MRSA) and Vancomycin Resistant Enterococcus faecalis (VRE) are two particularly virulent examples. In vivo studies have shown that the eukaryotic like 'mevalonate' isoprenoid pathway used by these pathogenic cocci is essential to their growth and virulence [1]. Our structures of HMG-CoA reductase (HMGR) from P. mevalonii demonstrated that the bacterial enzymes are structurally distinct from the human enzymes allowing for specific antibacterial activity [2]. High throughput in vitro screening against bacterial HMGR at the Southern Research Center, Birmingham, AL uncovered a lead compound with an IC50 of 80 µM with a competitive mode of action. Our x-ray crystal structures of HMGR from E. faecalis complexed with the lead compound and its variations have informed the synthesis of new inhibitors that have improved the IC50 to 5 µM [3]. Studies of this compound show it to be active against both MRSA and VRE in culture, effective against these bacteria in biofilms, and efficacious in a model system of eukaryotic infection. Structures and kinetics of these compounds will be presented and future directions discussed.

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Recombinant HNP-1 Produced by Escherichia coli Triggers Bacterial Apoptosis and Exhibits Antibacterial Activity against Drug-Resistant Bacteria

Microbiology Spectrum ◽

10.1128/spectrum.00860-21 ◽

2022 ◽

Author(s):

Qi Xie ◽

Yin Wang ◽

Mengmeng Zhang ◽

Shujia Wu ◽

Wei Wei ◽

...

Keyword(s):

Escherichia Coli ◽

Antibacterial Activity ◽

Mass Production ◽

Recombinant Protein Expression ◽

Cost Effective ◽

Resistant Bacteria ◽

Drug Resistant ◽

Effective Solution ◽

Drug Resistant Bacteria ◽

Human Neutrophil Peptide

Human neutrophil peptide-1 (HNP-1) is a promising antibiotic candidate, but its clinical application has been hampered by the difficulty of mass production and an inadequate understanding of its bactericidal mechanisms. In this study, we demonstrated that recombinant protein expression combined with ultrafiltration may be a simple and cost-effective solution to HNP-1 production.

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