In Vitro Antifungal Activity of Several Antimicrobial Compounds against Penicillium expansum

Fungicides used in the prevention and control of mold rots in stored apples are subjected to legal, social, and biological limitations. The aim of this study was to find an alternative to postharvest fungicides currently used in the prevention and control of blue mold rot caused by Penicillium expansum in apples. For this purpose, the antimicrobial activity and MIC of several substances against P. expansum were evaluated in vitro using different end point methods: agar diffusion assay, volatility method, and agar dilution and broth dilution MIC assays. Most of the substances tested are common food ingredients and have a recognized antimicrobial activity. Essential oils, such as thymol, eugenol, citral and cineole, vanillin, sodium hypochlorite, acetic acid, potassium sorbate, and hydrogen peroxide, were the substances evaluated. Thymol and citral were the essential oil components that showed the greatest inhibitory effects. The effectiveness of 5 and 10% hydrogen peroxide in growth inhibition of P. expansum in the agar diffusion assay was total, and its MIC as determined by the agar and broth dilution assays was less than 0.025%. These results indicate that the application of small quantities of hydrogen peroxide to the apple skin might be an alternative to fungicides in the elimination of P. expansum.

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Novel Quantitative Assays for Estimating the Antimicrobial Activity of Fresh Garlic Juice†,‡

Journal of Food Protection ◽

10.4315/0362-028x-64.2.189 ◽

2001 ◽

Vol 64 (2) ◽

pp. 189-194 ◽

Cited By ~ 9

Author(s):

R. UNAL ◽

H. P. FLEMING ◽

R. F. McFEETERS ◽

R. L. THOMPSON ◽

F. BREIDT ◽

...

Keyword(s):

Antimicrobial Activity ◽

Dose Response ◽

Ratio Method ◽

E Coli ◽

Agar Diffusion ◽

Dilution Assay ◽

Agar Diffusion Assay ◽

Slope Ratio Method ◽

Diffusion Assay ◽

Broth Dilution

Novel agar diffusion and broth dilution assays were developed for quantitatively estimating the antimicrobial activity of fresh garlic juice. Bacteria found to be inhibited by garlic juice in agar diffusion assay included two gram-positive and five gram-negative species. Leuconostoc mesenteroides was not inhibited. Escherichia coli B-103 (HB101, with pJH101, ampicillin resistant, 100 μg ml−1) was inhibited and chosen as the standard culture for quantitative assays. The agar diffusion assay was based on the slope ratio method, where the slope of dose response for garlic juice was divided by the slope of dose response for methylmethane thiosulfonate (MMTSO2). Juice from fresh garlic varied in activity between 1.76 and 2.31 μg of MMTSO2 per mg of garlic juice. The activity of juice decreased during 11 months of storage of garlic cloves at 5°C from 2.31 to less than 0.1 μg of MMTSO2 per mg of juice. The broth dilution assay also used the E. coli B-103 culture, which permitted selective enumeration of this bacterium when 100 μg ml−1 of ampicillin was incorporated into the enumerating agar. Selective enumeration was essential since the garlic juice was not sterile and, thus, contained natural flora. Growth of E. coli was unaffected by 0.1%, delayed by 0.25%, and completely inhibited at 0.5 and 2% garlic juice in broth during 24 h of incubation at 37°C. The minimum inhibition concentration of garlic juice by broth dilution assay was, thus, estimated to be 0.5%, which is equivalent to 3.46 μg of MMTSO2 per mg of garlic juice by the agar diffusion assay.

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Colistin and Isavuconazole Interact Synergistically In Vitro against Aspergillus nidulans and Aspergillus niger

Microorganisms ◽

10.3390/microorganisms8091447 ◽

2020 ◽

Vol 8 (9) ◽

pp. 1447

Author(s):

Patrick Schwarz ◽

Elie Djenontin ◽

Eric Dannaoui

Keyword(s):

Aspergillus Niger ◽

Aspergillus Nidulans ◽

Susceptibility Testing ◽

Antifungal Susceptibility ◽

Reference Method ◽

Important Species ◽

Agar Diffusion ◽

Agar Diffusion Assay ◽

Diffusion Assay

The in vitro interactions of isavuconazole in combination with colistin were evaluated against 55 clinical Aspergillus species isolates belonging to the five most important species (Aspergillus flavus, Aspergillus fumigatus, Aspergillus nidulans, Aspergillus niger, and Aspergillus terreus) responsible for human aspergillosis by a microdilution checkerboard technique based on the European Committee on Antimicrobial Susceptibility Testing (EUCAST) reference method for antifungal susceptibility testing. Selected isolates (A. nidulans, n = 10; A. niger, n = 15) were additionally evaluated by an agar diffusion assay using isavuconazole gradient concentration strips with or without colistin incorporated Roswell Parc Memorial Institute (RPMI) agar. Interpretation of the checkerboard results was done by the fractional inhibitory concentration index. Using the checkerboard method, combination isavuconazole–colistin was synergistic for 100% of the 15 A. nidulans isolates and for 60% of the 20 A. niger isolates. No interactions were found for any of the other isolates. By agar diffusion assay, minimal inhibitory concentrations (MICs) in combination decreased compared to isavuconazole alone for 92% of the isolates. No interactions were found for any A. nidulans isolates, but synergy was observed for 40% of the A. niger isolates. A poor essential agreement of EUCAST and gradient concentration strip MICs at ± 2 log2 dilutions with 0% was obtained. Antagonistic interactions were never observed regardless of the technique used.

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Antimicrobial activity of crude extracts and fractions of Vernonia polyanthes Less (assa-peixe) flowers

Revista Brasileira de Plantas Medicinais ◽

10.1590/1983-084x/14_110 ◽

2015 ◽

Vol 17 (4 suppl 2) ◽

pp. 909-914 ◽

Cited By ~ 1

Author(s):

K.K. WALTRICH ◽

J. HOSCHEID ◽

I.S. PROCHNAU

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Folk Medicine ◽

Ethyl Acetate Fraction ◽

Extraction Methods ◽

Agar Diffusion ◽

Test Organisms ◽

Agar Diffusion Assay ◽

Macerated Extract ◽

Diffusion Assay

ABSTRACT Vernonia polyanthes, known as “assa-peixe”, is a plant native to Brazil, and the decoction or infusion of its flowers, roots and leaves are used in folk medicine, being considered sources of diuretic, balsamic, anti-rheumatic substances, and are used in cases of bronchitis and persistent cough. The aim of the study was to evaluate the antimicrobial activity of the extract/fractions obtained by methanol maceration and infusion of V. polyanthes flower, also including qualitative identification of flower compounds, through phytochemical evaluation, using colorimetric tests. Identification tests for the presence of anthraquinones, tannins, flavonoids, saponins and alkaloids were performed. Microbiological evaluation was made through agar diffusion assay, using Escherichia coli, Staphylococcus aureus and Pseudomonasaeruginosa as test organisms. From the performed colorimetric tests it was possible to verify the presence of tannins and flavonoids in both extracts. Alkaloids were also observed in the macerated extract. The ethyl acetate fraction from the agar diffusion assay, from both extracts, presented microbial activity over Staphylococcus aureus. It was possible to qualitatively identify the floral compounds, and to show the differences between extraction methods, being methanol considered the best solvent to the extraction.

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Short microwave-assisted modular synthesis of naturally occurring oxygenated bibenzyls

Zeitschrift für Naturforschung B ◽

10.1515/znb-2015-0047 ◽

2015 ◽

Vol 70 (9) ◽

pp. 637-641 ◽

Cited By ~ 2

Author(s):

Jürgen Krauss ◽

Ursula Kopp ◽

Franz Bracher

Keyword(s):

Antimicrobial Activity ◽

Natural Products ◽

Microwave Assisted ◽

Modular Synthesis ◽

Agar Diffusion ◽

Naturally Occurring ◽

Agar Diffusion Assay ◽

Diffusion Assay

AbstractThe naturally occurring oxygenated bibenzyls lunularin and m-O-methyllunularin were prepared in a modular synthesis in four steps from two appropriate iodophenols and trimethylsilylacetylene utilizing microwave-assisted Sonogashira couplings as the crucial steps. The antimicrobial activity of the resulting natural products was evaluated in an agar diffusion assay.

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Geraniol and Linalool Loaded Nanoemulsions and Their Antimicrobial Activity

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Animal Science and Biotechnologies ◽

10.15835/buasvmcn-asb:0025 ◽

2017 ◽

Vol 74 (2) ◽

pp. 157 ◽

Cited By ~ 3

Author(s):

Igori BALTA ◽

Lucian BRINZAN ◽

Alexandros Ch. STRATAKOS ◽

Mark LINTON ◽

Carmel KELLY ◽

...

Keyword(s):

Antimicrobial Activity ◽

High Water ◽

Food Preservation ◽

Listeria Innocua ◽

High Water Content ◽

E Coli ◽

Hydrophobic Nature ◽

Agar Diffusion Assay ◽

Diffusion Assay

Geraniol and linalool have been found to be effective against foodborne microorganisms in vitro. However, due to their hydrophobic nature, it is difficult to achieve an even dispersion in foods with high water content resulting in dramatic loss of activity. The aim of the study was to fabricate geraniol or linalool nanoemulsions and investigate their effect against Escherichia coli K12, Listeria innocua and Pseudomonas lundensis in a meat simulation medium. The agar diffusion assay revealed that both geraniol and linalool had a potent antimicrobial activity against all bacteria. Dynamic light scattering showed that geraniol and linalool nanoemulsions had a mean diameter of 68.22±2.46 and 173.59±4.15 nm, respectively. Killing assay results showed that both nanoemulsions were able to significantly reduce E. coli and L. innocua counts by approx. 3 log CFU/ml. Ps. lundensis proved to be more resistant to both nanoemulsions showing a reduction of approx. 1.2 log CFU/ml,. Overall, this study showed that nanoemulsions loaded with geraniol or linalool represent a promising antimicrobial system to improve food preservation and food safety.

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Clinical and Microbiological Evaluation of the Carious Dentin Before and After Application of Papacarie Gel

Journal of Clinical Pediatric Dentistry ◽

10.17796/jcpd.38.2.2j237v545437527m ◽

2013 ◽

Vol 38 (2) ◽

pp. 133-138 ◽

Cited By ~ 3

Author(s):

S Gupta ◽

C Singh ◽

Y Ramakrishna ◽

K Chaudhry ◽

AK Munshi

Keyword(s):

Primary Teeth ◽

Patient Comfort ◽

Permanent Teeth ◽

Agar Diffusion ◽

Before And After ◽

Caries Removal ◽

Agar Diffusion Assay ◽

Caries Excavation ◽

Diffusion Assay

Objective: To evaluate clinically and microbiologically the efficacy of Papacarie® in the removal of carious dentin in both permanent and primary teeth. Study design: Thirty permanent and primary molars with dentinal carious lesions were excavated and subjected to clinical and microbiological assessment before and after application of Papacarie®. The gel was further tested for in vitro antimicrobial efficacy against standard cariogenic micro-organisms using agar diffusion assay. Results: Papacarie® was able to differentiate between infected and affected dentin clinically along with high patient comfort during caries excavation. The mean time taken for caries removal and restoration was observed to be 4.17 ± 0.40 min. and 8.57 ± 0.45 min. for permanent teeth and 4.21 ± 0.36 min. and 9.24 ± 0.58 min. for primary teeth. There was a significant reduction in the total viable colony forming units from the dentin samples before and after application of Papacarie®. It was also observed that Papacarie® had no inhibitory effect on standard cariogenic microorganisms in the agar diffusion assay. Conclusions: Papacarie® is an effective caries removal method clinically in both permanent and primary teeth. The number of viable microorganisms after complete caries excavation using Papacarie® still appears to be high and this bacterial count should be tackled by a suitable restorative material with potent antimicrobial activity.

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