Antibacterial activity of ethanolic leaf extract of Aquilaria malaccensis against multidrug-resistant Gram-negative pathogen

The rapid emergence of resistant Gram-negative bacteria and the limited discovery of novel antibiotic is a global healthcare challenge. Many medicinal plants with potent bioactivities have been developed for the treatment of bacterial infections. Aquilaria malaccensis exhibits wide applications from perfumes and aromatic foods ingredients and great potential in medicines. In this study, crude leaf extract of A. malaccensis was evaluated for its antibacterial activity against several pathogenic Gram-negative bacteria. The leaves were processed and extracted by Soxhlet method using ethanol as the solvent. The antibacterial activity of the crude extract was tested by disc diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Acinetobacter baumannii (ATCC 19606), Klebsiella pneumoniae (ATCC 10031 and ATCC 700603) and Escherichia coli (ATCC 1129). Using the optimized method, the Soxhlet extract produced a yield of 178.41 mg/g. Treatment of the extract at 200 mg/mL displayed the largest inhibition zones of 14.0 mm and 9.7 mm against A. baumannii and K. pneumoniae ATCC 10031, respectively. In contrast, against E. coli and K. pneumoniae ATCC 700603, smaller zones of inhibitions of 3.3 mm were demonstrated. The MIC values of the extract were 32 mg/mL against A. baumannii and K. pneumoniae ATCC 10031 and 64 mg/mL against E. coli and K. pneumoniae ATCC 700603. The MBC values of the extract were consistent with the MIC values for all the bacteria investigated. Overall, this study was the first to show antibacterial activity of A. malaccensis leaves extract particularly against A. baumannii and K. pneumoniae and potentially develop for the treatment of resistant bacteria.

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The Antibacterial Activity of Catunaregam tomentosa Against Selected Gram-Positive and Gram-Negative Bacteria

Asian Journal of Medicine and Biomedicine ◽

10.37231/ajmb.2021.5.s1.450 ◽

2021 ◽

Vol 5 (S1) ◽

pp. 34-38

Author(s):

Nor Aleesa Ali ◽

Wan Amalina Wan Mamat ◽

Syed Ahmad Tajudin Tuan Johari ◽

Muhammad Yusran Abdul Aziz ◽

Ahmad Syibli Othman

Keyword(s):

Antibacterial Activity ◽

Plant Extracts ◽

Bacterial Infections ◽

Scientific Basis ◽

Diffusion Method ◽

Antibacterial Drug ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Value Evaluation

Catunaregam tomentosa is a plant from Rubiaceae family that is used in traditional medicine for the treatment of stomatitis and ulcers due to bacterial infections. Besides, it also helps in the treatment of oliguria and dysuria. Indiscriminate use of commercial antibacterial medicines had led to the search for novel antibacterial drugs. Since for ages medicinal plants have been used to treat bacterial infection, so they can be excellent sources of the novel antibacterial drug. To evaluate the scientific basis of the use of plant, antibacterial activity leaves extract of C.tomentosa was investigated against selected Gram-positive and Gram-negative bacteria. The study also investigated the effect of pH on its antibacterial activity. Antibacterial activity of the plant extracts was evaluated against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa by using the disc diffusion method at 100mg/mL concentration. Extracts of C. tomentosa inhibit the activity of S. aureus but do not inhibit the activity of Gram-negative bacteria. Minimum inhibitory concentration (MIC) was also determined against S. aureus at concentration 100, 50, 25, 12.5, 6, 3, 1.5, 0.75 and 0.395mg/mL and 3mg/mL were the MIC value. Evaluation on the effect of different pH on antibacterial activity of plant extracts shows that the activity of the plant extracts does not affect when treated with acidic pH but increased at alkaline pH. Based on the present finding, C. tomentosa leaves extract have the potential to be a viable candidate in the discovery of a natural antibacterial agent against S. aureus infections. This study provides scientific knowledge to further determine the antibacterial values of C. tomentosa extracts.

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Evaluation of antibacterial activity of vitamin C against human bacterial pathogens

Brazilian Journal of Biology ◽

10.1590/1519-6984.247165 ◽

2023 ◽

Vol 83 ◽

Author(s):

S. Mumtaz ◽

S. Ali ◽

H. M. Tahir ◽

S. A. R. Kazmi ◽

...

Keyword(s):

Antibacterial Activity ◽

Vitamin C ◽

Bacterial Infections ◽

Unmet Need ◽

Diffusion Method ◽

Gram Negative Bacteria ◽

Bacterial Strains ◽

Gram Positive ◽

Gram Negative ◽

Adjunct Treatment

Abstract Now a day’s multidrug resistance phenomenon has become the main cause for concern and there has been an inadequate achievement in the development of novel antibiotics to treat the bacterial infections. Therefore, there is an unmet need to search for novel adjuvant. Vitamin C is one such promising adjuvant. The present study was aimed to elucidate the antibacterial effect of vitamin C at various temperatures (4°C, 37°C and 50°C) and pH (3, 8, and 11), against Gram-positive and Gram-negative bacteria at various concentrations (5-20 mg/ml) through agar well diffusion method. Growth inhibition of all bacterial strains by vitamin C was concentration-dependent. Vitamin C significantly inhibited the growth of Gram-positive bacteria: Bacillus licheniformis (25.3 ± 0.9 mm), Staphylococcus aureus (22.0 ± 0.6 mm), Bacillus subtilis (19.3 ± 0.3 mm) and Gram-negative bacteria: Proteus mirabilis (27.67 ± 0.882 mm), Klebsiella pneumoniae (21.33±0.9 mm), Pseudomonas aeruginosa (18.0 ± 1.5 mm) and Escherichia coli (18.3 ± 0.3 mm). The stability of vitamin C was observed at various pH values and various temperatures. Vitamin C showed significant antibacterial activity at acidic pH against all bacterial strains. Vitamin C remained the stable at different temperatures. It was concluded that vitamin C is an effective and safe antibacterial agent that can be used in the future as an adjunct treatment option to combat infections in humans.

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Mode of action of the 2-phenylquinoline efflux inhibitor PQQ4R againstEscherichia coli

PeerJ ◽

10.7717/peerj.3168 ◽

2017 ◽

Vol 5 ◽

pp. e3168 ◽

Cited By ~ 14

Author(s):

Diana Machado ◽

Laura Fernandes ◽

Sofia S. Costa ◽

Rolando Cannalire ◽

Giuseppe Manfroni ◽

...

Keyword(s):

Mode Of Action ◽

Bacterial Infections ◽

Efflux Pump ◽

Resistant Bacteria ◽

Gram Negative Bacteria ◽

Synergistic Activity ◽

Dependent Manner ◽

Gram Negative ◽

E Coli ◽

Efflux Pump Inhibitors

Efflux pump inhibitors are of great interest since their use as adjuvants of bacterial chemotherapy can increase the intracellular concentrations of the antibiotics and assist in the battle against the rising of antibiotic-resistant bacteria. In this work, we have described the mode of action of the 2-phenylquinoline efflux inhibitor (4-(2-(piperazin-1-yl)ethoxy)-2-(4-propoxyphenyl) quinolone – PQQ4R), againstEscherichia coli,by studding its efflux inhibitory ability, its synergistic activity in combination with antibiotics, and compared its effects with the inhibitors phenyl-arginine-β-naphthylamide (PAβN) and chlorpromazine (CPZ). The results showed that PQQ4R acts synergistically, in a concentration dependent manner, with antibiotics known to be subject to efflux inE. colireducing their MIC in correlation with the inhibition of their efflux. Real-time fluorometry assays demonstrated that PQQ4R at sub-inhibitory concentrations promote the intracellular accumulation of ethidium bromide inhibiting its efflux similarly to PAβN or CPZ, well-known and described efflux pump inhibitors for Gram-negative bacteria and whose clinical usage is limited by their levels of toxicity at clinical and bacteriological effective concentrations. The time-kill studies showed that PQQ4R, at bactericidal concentrations, has a rapid antimicrobial activity associated with a fast decrease of the intracellular ATP levels. The results also indicated that the mode of action of PQQ4R involves the destabilization of theE. coliinner membrane potential and ATP production impairment, ultimately leading to efflux pump inhibition by interference with the energy required by the efflux systems. At bactericidal concentrations, membrane permeabilization increases and finally ATP is totally depleted leading to cell death. Since drug resistance mediated by the activity of efflux pumps depends largely on the proton motive force (PMF), dissipaters of PMF such as PQQ4R, can be regarded as future adjuvants of conventional therapy againstE. coliand other Gram-negative bacteria, especially their multidrug resistant forms. Their major limitation is the high toxicity for human cells at the concentrations needed to be effective against bacteria. Their future molecular optimization to improve the efflux inhibitory properties and reduce relative toxicity will optimize their potential for clinical usage against multi-drug resistant bacterial infections due to efflux.

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Bacterial Pattern of Community acquired Urinary Tract Infections: A Challenge for Antimicrobial Resistance

10.51429/ejmm30320 ◽

2021 ◽

Vol 30 (3) ◽

pp. 153-162

Author(s):

Nader A. Nemr ◽

Rania M. Kishk ◽

Mohammed Abdou ◽

Hassnaa Nassar ◽

Noha M Abu bakr Elsaid ◽

...

Keyword(s):

Urinary Tract ◽

Antimicrobial Resistance ◽

Bacterial Infections ◽

Diffusion Method ◽

Gram Negative Bacteria ◽

Isolation And Identification ◽

Gram Positive ◽

Gram Negative ◽

E Coli ◽

Tract Infections

Background: Urinary tract infection (UTI) is considered one of the most common bacterial infections seen in health care. To our knowledge, there is no available antimicrobial resistance surveillance system for monitoring of community-acquired UTIs (CA- UTIs) in our country. Objectives: we aimed to discuss the bacterial pattern and resistance profile of CA-UTIs in Ismailia, Egypt. Methods: This cross-sectional study included 400 patients suffering from symptoms of acute UTIs. Urine specimens were collected by clean-catch mid-stream method, examined microscopically and inoculated immediately on blood agar and MacConkey's agar plates. Colony counting, isolation and identification of the urinary pathogens were performed by the conventional biochemical tests according to the isolated organism. Antibiotic susceptibility testing was performed by Kirby Bauer disk diffusion method. Interpretation was performed according to Clinical Laboratory Standard Institute (CLSI) guidelines. Results: out of 400 specimens, 136 of them revealed no bacterial growth or insignificant bacteriuria. Most of participants with UTI were females (81.8%) (p=0.008) and 54.5% of them were married (P=0.1). Gram negative bacteria were more common than Gram positive representing 66 % and 34% respectively. E. coli was the most common isolated organism (39%) followed by S. aureus (32%), K. Pneumoniae and Pseudomonas (10.5% for each), Proteus (6%) and Enterococci (2%). E. coli isolates showed the highest susceptibility to imipenem, meropenem, amikacin, nitrofurantoin, levofloxacin and ciprofloxacin. Most of our patients were diabetics (64.8%) (p=0.004). The mean ± SD of HbA1c was 6.4±2.0 with 4 to 12.6 range, S.E was 0.1 and 95% C.I was 6.2- 6.7. The highest mean ± SD of HbA1c was in S. aureus infections. Conclusion: Gram negative bacteria were most common than Gram positive with predominance of E. coli with significant relation to the presence of diabetes.

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Antibacterial Activity of Borassus flabellifer Vinegar-Graphene Quantum Dots Against Gram-Positive and Gram-Negative Bacteria

Asian Journal of Chemistry ◽

10.14233/ajchem.2021.23376 ◽

2021 ◽

Vol 33 (11) ◽

pp. 2662-2666

Author(s):

Amnuay Noypha ◽

Paweena Porrawatkul ◽

Nongyao Teppaya ◽

Parintip Rattanaburi ◽

Saksit Chanthai ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Quantum Dots ◽

Antibacterial Activity ◽

Graphene Quantum Dots ◽

Diffusion Method ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

E Coli

Borassus flabellifer vinegar–graphene quantum dots (BFV-GQDs) were successfully synthesized using a pyrolysis method with Borassus flabellifer vinegar (BFV) as the precursor. All the samples were characterized using ultraviolet-visible spectrophotometry (UV-Vis), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The antibacterial activities of BFV-GQDs against strains of Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were determined using the agar well diffusion method for preliminary screening, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the broth macro-dilution method. The zones of inhibition were compared with those of citric acid–graphene quantum dots (CA-GQDs). It was observed that the synthesized BFV-GQDs demonstrated excellent antibacterial activity against Staphylococcus aureus (82.3%) and good antibacterial activity against Escherichia coli (73.3%). The MIC of BFV-GQDs against E. coli was 6.25 mg/mL and S. aureus was 12.5 mg/mL, whereas the MBC of BFV-GQDs against E. coli was 12.5 mg/mL and S. aureus was 25.0 mg/mL.

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Test for the antibacterial inhibition of kaffir lime leaf (Citrus hysteric D.C) extract against pathogen bacteria in improving food safety

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/883/1/012056 ◽

2021 ◽

Vol 883 (1) ◽

pp. 012056

Author(s):

S J Nendissa ◽

D M Nendissa

Keyword(s):

Antibacterial Activity ◽

Food Safety ◽

Salmonella Typhimurium ◽

Pathogenic Bacteria ◽

Leaf Extract ◽

Diffusion Method ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Gram Positive Bacteria

Abstract Kafir lime leaf (Citrus hystrix) is a plant from the citrus tribe that has long been known by community as flavor ingredient. To support its use and increase its application in supporting food safety, a test the inhibition of on kaffir lime leaf extract against pathogenic bacteria, namely Gram Negative Bacteria (Escherichia coli, Salmonella typhimurium) and Gram Positive bacteria (Staphylococcus aereus, P. aeroginosa). Making kaffir lime leaf extract (Citrus hystrix) was done by weighing 150g of lime leaf powder, then immersing in 96% ethanol solution and leaving for + 3 days. Kaffir lime leaf extract was dissolved with sterile distilled aquades to obtain a concentration of 5%, 10% and 15%. The antibacterial activity of kaffir lime leaf extract was tested by diffusion method using disc paper to determine of the bacterial growth inhibition area. The results showed that kaffir lime extract had antibacterial activity inhibition of 12,78 mm of S. aereus, 9 mm of E.coli, 7,12 mm of S. typhimurium and 9,3 mm of P. aeroginosa. Kaffir lime leaf extract has inhibition effectiveness for gram positive bacteria Staphylococcus aereus and gram negative bacteria E. coli, Salmonella typhimurium, P. aeroginosa. Thus, kaffir lime leaf extract can be used as a decontaminant agait theses 4 type of bacteria, especially Staphylococcus aereus which has a strong inhibitory power, so it can maintain quality and increase the safety of mead based foods

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In-vitro Antioxidant and Antibacterial Activity of Methanolic Extract of Shorea robusta Gaertn. F. Resin

International Journal of Pharmaceutical and Phytopharmacological Research ◽

10.24896/eijppr.2016641 ◽

2016 ◽

Vol 6 (4) ◽

pp. 68

Author(s):

Sushma Vashisht ◽

Manish Pal Singh ◽

Viney Chawla

Keyword(s):

Antibacterial Activity ◽

Methanolic Extract ◽

Diffusion Method ◽

Gram Negative Bacteria ◽

Disc Diffusion ◽

Gram Positive ◽

Gram Negative ◽

Shorea Robusta ◽

Dose Dependent ◽

Resin Extract

The methanolic extract of the resin of Shorea robusta was subjected to investigate its antioxidant and antibacterial properties its utility in free radical mediated diseases including diabetic, cardiovascular, cancer etc. The methanol extract of the resin was tested for antioxidant activity using scavenging activity of DPPH (1,1-diphenyl-2-picrylhydrazil) radical method, reducing power by FeCl3 and antibacterial activity against gram positive and gram negative bacteria using disc diffusion method. The phytochemical screening considered the presence of triterpenoids, tannins and flavoniods. Overall, the plant extract is a source of natural antioxidants which might be helpful in preventing the progress of various oxidative stress mediated diseases including aging. The half inhibition concentration (IC50) of resin extract of Shorea robusta and ascorbic acid were 35.60 µg/ml and 31.91 µg/ml respectively. The resin extract exhibit a significant dose dependent inhibition of DPPH activity. Antibacterial activity was observed against gram positive and gram negative bacteria in dose dependent manner.Key Words: Shorea robusta, antioxidant, antibacterial, Disc-diffusion, DPPH.

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Antibacterial activity of magnesium oxide nanoparticles prepared by Calcination method

International Journal of Pharmaceutical Quality Assurance ◽

10.25258/ijpqa.10.3.25 ◽

2019 ◽

Vol 10 (03) ◽

Author(s):

Elaf Ayad Kadhem ◽

Miaad Hamzah Zghair ◽

Sarah , Hussam H. Tizkam, Shoeb Alahmad Salih Mahdi ◽

Hussam H. Tizkam ◽

Shoeb Alahmad

Keyword(s):

Antibacterial Activity ◽

Magnesium Oxide ◽

Diffusion Method ◽

Oxide Nanoparticles ◽

Gram Negative Bacteria ◽

Gram Positive ◽

Gram Negative ◽

Gram Positive Bacteria ◽

Magnesium Oxide Nanoparticles ◽

Agar Disc

magnesium oxide nanoparticles (MgO NPs) were prepared by simple wet chemical method using different calcination temperatures. The prepared NPs were characterized by Electrostatic Discharge (ESD), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). It demonstrates sharp intensive peak with the increase of crystallinty and increase of the size with varying morphologies with respect to increase of calcination temperature. Antibacterial studies were done on gram negative bacteria (E.coli) and gram positive bacteria (S.aureus) by agar disc diffusion method. The zones of inhibitions were found larger for gram positive bacteria than gram negative bacteria, this mean, antibacterial MgO NPs activity more active on gram positive bacteria than gram negative bacteria because of the structural differences. It was found that antibacterial activity of MgO NPs was found it has directly proportional with their concentration.

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Structure-Activity Relationship and Antimicrobial Evaluation of N-Phenylpyrazole Curcumin Derivatives

Current Bioactive Compounds ◽

10.2174/1573407215666190124115010 ◽

2020 ◽

Vol 16 (4) ◽

pp. 481-488

Author(s):

Heli Sanghvi ◽

Satyendra Mishra

Keyword(s):

Antibacterial Activity ◽

Gram Negative Bacteria ◽

Pyrazole Derivatives ◽

Gram Positive ◽

Gram Negative ◽

E Coli ◽

Curcumin Derivatives ◽

Structure Activity ◽

Electron Donating Groups ◽

Derivatives Of

Background: Curcumin, one of the most important pharmacologically significant natural products, has gained significant consideration among scientists for decades since its multipharmacological activities. 1, 3-Dicarbonyl moiety of curcumin was found to be accountable for the rapid degradation of curcumin molecule. The aim of present work is to replace 1, 3-dicarbonyl moiety of curcumin by pyrazole and phenylpyrazole derivatives with a view to improving its stability and to investigate the role of substitution in N-phenylpyrazole curcumin on its antibacterial activity against both Gram-positive as well as Gram-negative bacteria. Methods: Pyrazole derivatives of curcumin were prepared by heating curcumin with phenyhydrazine/ substituted phenyhydrazine derivatives in AcOH. The residue was purified by silica gel column chromatography. Structures of purified compounds were confirmed by 1H NMR and Mass spectroscopy. The synthesized compounds were evaluated for their antibacterial activity by the microdilution broth susceptibility test method against gram positive (S. aureus) and gram negative (E. coli). Results: Effects of substitution in N-phenylpyrazole curcumin derivatives against S. aureus and E. coli were studied. The most active N-(3-Nitrophenylpyrazole) curcumin (12) exhibits twenty-fold more potency against S. aureus (MIC: 10μg/mL)) and N-(2-Fluoroophenylpyrazole) curcumin (5) fivefold more potency against E. coli (MIC; 50 μg/mL) than N-phenylpyrazole curcumin (4). Whereas, a remarkable decline in anti-bacterial activity against S. aureus and E. coli was observed when electron donating groups were incorporated in N-phenylpyrazole curcumin (4). Comparative studies of synthesized compounds suggest the effects of electron withdrawing and electron donating groups on unsubstituted phenylpyrazole curcumin (4). Conclusion: The structure-activity relationship (SAR) results indicated that the electron withdrawing and electron donating at N-phenylpyrazole curcumin played key roles for their bacterial inhibitory effects. The results of the antibacterial evaluation showed that the synthesized pyrazole derivatives of curcumin displayed moderate to very high activity in S. aureus. In conclusion, the series of novel curcumin derivatives were designed, synthesized and tested for their antibacterial activities against S. aureus and E. coli. Among them, N-(3-Nitrophenylpyrazole curcumin; 12) was most active against S. aureus (Gram-positive) and N-(2-Fluoroophenylpyrazole) curcumin (5) against E. coli (Gram-negative) bacteria.

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Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin

BMC Microbiology ◽

10.1186/s12866-021-02176-4 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Tessa B. Moyer ◽

Ashleigh L. Purvis ◽

Andrew J. Wommack ◽

Leslie M. Hicks

Keyword(s):

Escherichia Coli ◽

Antibacterial Activity ◽

Antimicrobial Peptides ◽

Mechanism Of Action ◽

Gram Negative Bacteria ◽

Amaranthus Tricolor ◽

Core Motif ◽

Gram Negative ◽

E Coli ◽

Membrane Lysis

Abstract Background Plant defensins are a broadly distributed family of antimicrobial peptides which have been primarily studied for agriculturally relevant antifungal activity. Recent studies have probed defensins against Gram-negative bacteria revealing evidence for multiple mechanisms of action including membrane lysis and ribosomal inhibition. Herein, a truncated synthetic analog containing the γ-core motif of Amaranthus tricolor DEF2 (Atr-DEF2) reveals Gram-negative antibacterial activity and its mechanism of action is probed via proteomics, outer membrane permeability studies, and iron reduction/chelation assays. Results Atr-DEF2(G39-C54) demonstrated activity against two Gram-negative human bacterial pathogens, Escherichia coli and Klebsiella pneumoniae. Quantitative proteomics revealed changes in the E. coli proteome in response to treatment of sub-lethal concentrations of the truncated defensin, including bacterial outer membrane (OM) and iron acquisition/processing related proteins. Modification of OM charge is a common response of Gram-negative bacteria to membrane lytic antimicrobial peptides (AMPs) to reduce electrostatic interactions, and this mechanism of action was confirmed for Atr-DEF2(G39-C54) via an N-phenylnaphthalen-1-amine uptake assay. Additionally, in vitro assays confirmed the capacity of Atr-DEF2(G39-C54) to reduce Fe3+ and chelate Fe2+ at cell culture relevant concentrations, thus limiting the availability of essential enzymatic cofactors. Conclusions This study highlights the utility of plant defensin γ-core motif synthetic analogs for characterization of novel defensin activity. Proteomic changes in E. coli after treatment with Atr-DEF2(G39-C54) supported the hypothesis that membrane lysis is an important component of γ-core motif mediated antibacterial activity but also emphasized that other properties, such as metal sequestration, may contribute to a multifaceted mechanism of action.

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