Physical, Thermal, and Antibacterial Effects of Active Essential Oils with Potential for Biomedical Applications Loaded onto Cellulose Acetate/Polycaprolactone Wet-Spun Microfibers

New approaches to deal with the growing concern associated with antibiotic-resistant bacteria are emerging daily. Essential oils (EOs) are natural antimicrobial substances with great potential to mitigate this situation. However, their volatile nature, in their liquid-free form, has restricted their generalized application in biomedicine. Here, we propose the use of cellulose acetate (CA)/polycaprolactone (PCL) wet-spun fibers as potential delivery platforms of selected EOs to fight infections caused by Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Twenty EOs were selected and screened for their minimal inhibitory concentration (MIC), using the antibiotic ampicillin as positive control. The cinnamon leaf oil (CLO), cajeput oil (CJO), and the clove oil (CO) were the most effective EOs, against the Gram-positive (MIC < 22.38 mg/mL) and the Gram-negative (MIC < 11.19 mg/mL) bacteria. Uniform microfibers were successfully wet-spun from CA/PCL with an averaged diameter of 53.9 ± 4.5 µm, and then modified by immersion with CLO, CJO and CO at 2 × MIC value. EOs incorporation was confirmed by UV-visible spectroscopy, Fourier-transformed infrared spectroscopy, and thermal gravimetric analysis. However, while microfibers contained ampicillin at MIC (control) after the 72 h modification, the CLO, CO and CJO-loaded fibers registered ≈ 14%, 66%, and 76% of their MIC value, respectively. Data showed that even at small amounts the EO-modified microfibers were effective against the tested bacteria, both by killing bacteria more quickly or by disrupting more easily their cytoplasmic membrane than ampicillin. Considering the amount immobilized, CLO-modified fibers were deemed the most effective from the EOs group. These results indicate that CA/PCL microfibers loaded with EOs can be easily produced with increased antibacterial action, envisioning their use as scaffolding materials for the treatment of infections.

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In vitro antibacterial activity of several plant extracts and essential oils against Brucella melitensis

Herba Polonica ◽

10.2478/hepo-2014-0003 ◽

2014 ◽

Vol 60 (1) ◽

pp. 29-38

Author(s):

Mazen Safi ◽

Ayman Al-Mariri

Keyword(s):

Medicinal Plants ◽

Essential Oils ◽

Plant Extract ◽

Plant Extracts ◽

Brucella Melitensis ◽

Diffusion Method ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Fluid Medium

Summary Medicinal plants are considered to be new resources for the production of agents that could act as alternatives to antibiotics in the treatment of antibiotic-resistant bacteria. The aim of this study was to evaluate the efficacy of some plants native to Syria in the treatment of brucellosis. In vitro activities of some essential oils and plant extracts of some medicinal plants against 89 Brucella melitensis isolates was determined by disc diffusion method at a concentration of 5%. The microdilution assay in the fluid medium was used to determine the MICs of essential oils and plant extracts. Among the evaluated herbs, only Thymus syriacus and Cinnamomum zeylanicum essential oils and Laurus nobilis plant extract showed a high activity against B. melitensis strains. Thus, minimal inhibitory concentration (MIC50) values for T. syriacus, C. zeylanicum, and L. nobilis against B. melitensis were 6.25, 3.125 and 6.25 μl/ml, respectively. Among studied essential oils and plant extracts, T. syriacus and C. zeylanicum essential oils, and L. nobilis plant extract were the most effective ones. Moreover, T. syriacus - C. zeylanicum combination was more effective than use of each of them alone. Then, T. syriacus and C. zeylanicum essential oils and L. nobilis plant extract could act as bactericidal agents against B. melitensis.

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Comparative in vitro efficacy of eight essential oils as antibacterial agents against pathogenic bacteria isolated from pet-turtles

Veterinární Medicína ◽

10.17221/142/2017-vetmed ◽

2018 ◽

Vol 63 (No. 7) ◽

pp. 335-343 ◽

Cited By ~ 1

Author(s):

BCJ De Silva ◽

S. Hossain ◽

SHMP Wimalasena ◽

HNKS Pathirana ◽

PS Dahanayake ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Essential Oils ◽

Pathogenic Bacteria ◽

Antibacterial Agents ◽

Bacterial Species ◽

Antimicrobial Properties ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Drug Resistant Bacteria

Essential oils are plant extracts that have been used for their antimicrobial properties for centuries. The keeping of turtles as pets exhibits a growing trend worldwide but these animals are known to harbour a range of pathogenic bacteria. In the current study, we assessed eight essential oils as alternative antibacterial agents against nine species of pet turtle-borne Gram-negative bacteria, namely Aeromonas caviae, A. dhakensis, A. hydrophila, Citrobacter freundii, Morganella morganii, Proteus mirabilis, P. vulgaris, Pseudomonas aeruginosa and Salmonella enterica. Except for Pseudomonas aeruginosa, all other bacterial species showed high susceptibility to six essential oils, namely oregano, cinnamon, clove, lemongrass, lavender and eucalyptus oils in descending order of efficacy. Minimum inhibitory concentrations and minimum bactericidal concentrations values of the essential oils against all tested species except for P. aeruginosa showed low heterogeneity, showing that these essential oils can effectively control the growth of nearly all the tested. However, most of the tested bacteria were multiple-antibiotic-resistant as determined in the antibiotic disc diffusion test, with multiple-antibiotic-resistant index values of ≥ 0.2 for most of the strains. Therefore, with regards to their in vitro activity in controlling growth of multi-drug resistant bacteria, we can classify oregano, cinnamon, clove, lemongrass, lavender and eucalyptus essential oils as effective antibacterial agents. Thus, prospective application of these essential oils in controlling and treating these bacteria should be considered.

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Essential Oils: A Natural Weapon against Antibiotic-Resistant Bacteria Responsible for Nosocomial Infections

Antibiotics ◽

10.3390/antibiotics10040417 ◽

2021 ◽

Vol 10 (4) ◽

pp. 417

Author(s):

Ramona Iseppi ◽

Martina Mariani ◽

Carla Condò ◽

Carla Sabia ◽

Patrizia Messi

Keyword(s):

Essential Oils ◽

Therapeutic Strategy ◽

Resistant Bacteria ◽

Antibiotic Resistant Bacteria ◽

Cupressus Sempervirens ◽

Antibiotic Resistant ◽

Agar Disc ◽

Resistant Strains ◽

Vancomycin Resistant ◽

Better Than

The emergence of antibiotic-resistant bacteria has become a major concern worldwide. This trend indicates the need for alternative agents to antibiotics, such as natural compounds of plant origin. Using agar disc diffusion and minimum inhibitory concentration (MIC) assays, we investigated the antimicrobial activity of Citrus aurantium (AEO), Citrus x limon (LEO), Eucalyptus globulus (EEO), Melaleuca alternifolia (TTO), and Cupressus sempervirens (CEO) essential oils (EOs) against three representatives of antibiotic-resistant pathogens and respective biofilms: vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli. Using the checkerboard method, the efficacy of the EOs alone, in an association with each other, or in combination with the reference antibiotics was quantified by calculating fractional inhibitory concentrations (FICs). All the EOs displayed antibacterial activity against all strains to different extents, and TTO was the most effective. The results of the EO–EO associations and EO–antibiotic combinations clearly showed a synergistic outcome in most tests. Lastly, the effectiveness of EOs both alone and in association or combination against biofilm formed by the antibiotic-resistant strains was comparable to, and sometimes better than, that of the reference antibiotics. In conclusion, the combination of EOs and antibiotics represents a promising therapeutic strategy against antibiotic-resistant bacteria, even protected inside biofilms, which can allow decreasing the concentrations of antibiotics used.

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Magnetite Nanoparticles and Essential Oils Systems for Advanced Antibacterial Therapies

International Journal of Molecular Sciences ◽

10.3390/ijms21197355 ◽

2020 ◽

Vol 21 (19) ◽

pp. 7355

Author(s):

Antonio David Mihai ◽

Cristina Chircov ◽

Alexandru Mihai Grumezescu ◽

Alina Maria Holban

Keyword(s):

Essential Oils ◽

Magnetite Nanoparticles ◽

Antibacterial Agents ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Prosthetic Devices ◽

The Past ◽

Efficient Delivery ◽

Synthesis Properties ◽

Low Toxicity

Essential oils (EOs) have attracted considerable interest in the past few years, with increasing evidence of their antibacterial, antiviral, antifungal, and insecticidal effects. However, as they are highly volatile, the administration of EOs to achieve the desired effects is challenging. Therefore, nanotechnology-based strategies for developing nanoscaled carriers for their efficient delivery might offer potential solutions. Owing to their biocompatibility, biodegradability, low toxicity, ability to target a tissue specifically, and primary structures that allow for the attachment of various therapeutics, magnetite nanoparticles (MNPs) are an example of such nanocarriers that could be used for the efficient delivery of EOs for antimicrobial therapies. The aim of this paper is to provide an overview of the use of EOs as antibacterial agents when coupled with magnetite nanoparticles (NPs), emphasizing the synthesis, properties and functionalization of such NPs to enhance their efficiency. In this manner, systems comprising EOs and MNPs could offer potential solutions that could overcome the challenges associated with biofilm formation on prosthetic devices and antibiotic-resistant bacteria by ensuring a controlled and sustained release of the antibacterial agents.

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Chemical Composition, Antibacterial and α-Glucosidase Inhibitory Activities of the Essential Oils of Neolitsea coccinea (Lauraceae)

Natural Product Communications ◽

10.1177/1934578x1601101231 ◽

2016 ◽

Vol 11 (12) ◽

pp. 1934578X1601101 ◽

Cited By ~ 1

Author(s):

Nor Akmalazura Jani ◽

Hasnah Mohd Sirat ◽

Farediah Ahmad ◽

Nor Azah Mohamad Ali ◽

Muhd Hafizi Zainal

Keyword(s):

Antibacterial Activity ◽

Chemical Composition ◽

Essential Oils ◽

Germacrene D ◽

Leaf Oil ◽

Inhibitory Activities ◽

First Time ◽

Weak Antibacterial Activity ◽

And Staphylococcus Aureus ◽

Mic Value

The chemical composition, antibacterial and α-glucosidase inhibitory activities of the essential oils obtained from hydrodistillation of the fresh stem and leaf of Neolitsea coccinea B. C. Stone are reported for the first time. GC and GC-MS analysis revealed the presence of 42 volatile compounds from the stem and leaf oils, accounting for 84.9% and 90.4%, respectively of the identified components. The principle compounds in the stem oil were δ-cadinene (21.2%), 1-epi-cubenol (11.3%) and cyperotundone (10.7%), while the main compounds in the leaf oil were selin-11-en-4-α-ol (26.8%), bicyclogermacrene (12.6%), γ-eudesmol (7.1%), germacrene D (6.1%) and globulol (5.9%). The leaf oil demonstrated moderate to weak antibacterial activity towards Bacillus subtilis and Staphylococcus aureus with MIC values of 250 μg/mL and 500 μg/mL, respectively, whereas the stem oil possessed weak antibacterial activity against B. subtilis with a MIC value of 500 μg/mL. The stem and leaf oils showed significant α-glucosidase inhibitory activity with IC50 values of 32.2 ± 0.8 μg/mL and 70.9 ± 1.1 μg/mL, respectively.

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Synergistic Effects of Three Moroccan Thyme Essential Oils with Antibiotic Cefixime

Phytothérapie ◽

10.3166/phyto-2019-0143 ◽

2018 ◽

Vol 16 (S1) ◽

pp. S149-S154 ◽

Cited By ~ 2

Author(s):

C. Alaoui Jamali ◽

A. Kasrati ◽

M. Fadli ◽

L. Hassani ◽

D. Leach ◽

...

Keyword(s):

Essential Oils ◽

Pathogenic Bacteria ◽

Inhibitory Concentration ◽

Synergistic Effects ◽

Synergistic Interaction ◽

Resistant Bacteria ◽

Antibiotic Resistant ◽

Promising Solution ◽

First Time ◽

Concentration Indices

The association of essential oils (EOs) with antibiotics provides a promising solution towards combating resistant bacteria. Thus, the aim of this study was to examine for the first time the possible synergistic interaction between EOs of three Moroccan thymes, namely Thymus leptobotrys (carvacrol [79.1%]), Thymus pallidus (γ-terpinene [29.6%], thymol [26.8%] and p-cymene [18.9%]) and Thymus ciliatus (carvacrol [26.2%], p-cymene [19.6%], thymol [17.3%] and γ-terpinene [14.6%]) and the antibiotic cefixime against selected pathogenic bacteria. The results showed that all thyme EOs presented interesting antibacterial potency and important synergistic effects with cefixime. Thymus leptobotrys EO showed the strongest efficacy against all tested bacteria (minimum inhibitory concentration values 0.14 mg/mL to 73.92 mg/mL), and the best synergistic effect (fractional inhibitor concentration indices: 0.26 to 0.5; gain: 4- to 130- fold). This synergistic interaction between the studied thyme EOs and cefixime may provide a basis for future applications for the control of antibiotic-resistant bacteria.

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