Encapsulation of Essential Oils within a Polymeric Liposomal Formulation for Enhancement of Antimicrobial Efficacy

Essential oils and their constituents are known to possess antimicrobial activity; however, their inherent volatility is a limiting factor. In order to exploit the antimicrobial efficacy of essential oils, encapsulation within polymeric liposomal systems was undertaken. The liposomes were subsequently polymer-coated in order to further enhance the stability of the formulations. Essential oils distilled from Artemisia Afra, Eucalyptus Globulus and Melaleuca alternifolia were encapsulated into diastearoyl phosphatidylcholine and diastearoyl phosphatidylethanolamine liposomes employing a reverse phase evaporation methodology. A polyelectrolyte coating was then applied via the layer-by-layer self-deposition technique. A batch of the liposomes was polymer-coated with a 0.15%w/v chitosan solution. Using the minimum inhibitory concentration assay, the liposome-encapsulated, unencapsulated and polymer-coated liposome-encapsulated essential oils were compared in order to observe whether the antimicrobial efficacy was improved with encapsulation and polymer coating. Fractional inhibitory concentrations (FICs) were calculated in order to determine the antimicrobial interactions amongst the lipoid components, polymer coating and essential oils (synergistic, additive, indifferent and antagonistic interactions). With the exception of A. afra, microbial growth was inhibited at lower concentrations for the encapsulated formulations in comparison with the non-encapsulated oils. Synergistic to additive interactions were noted for encapsulated E. globulus (ΣFIC values 0.25-0.45) and M. alternifolia (ΣFIC values 0.26-0.52) formulations. The addition of the polymer coating did not enhance antimicrobial activity, but owing to their positive effects on membrane stability, its presence is important as a means of extending the shelf life of these formulations. Additionally, the presence of the polymeric coating availed the essential oil at a slower rate. This investigation is a stepping stone towards the promotion of the antimicrobial use of essential oils. The added benefits are that essential oils not only provide effective antimicrobial efficacy, but also promote a “greener” consumerism. Within liposomes, they will enhance dermato-cosmetic properties and increase the marketing image of the final product.

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Antimicrobial Essential Oil Combinations to Combat Foot Odour

Planta Medica ◽

10.1055/a-0592-8022 ◽

2018 ◽

Vol 84 (09/10) ◽

pp. 662-673 ◽

Cited By ~ 4

Author(s):

Ané Orchard ◽

Alvaro Viljoen ◽

Sandy van Vuuren

Keyword(s):

Antimicrobial Activity ◽

Essential Oil ◽

Essential Oils ◽

Antimicrobial Efficacy ◽

Juniperus Virginiana ◽

Broth Microdilution ◽

Synergistic Interactions ◽

Microdilution Method ◽

Broth Microdilution Method

AbstractFoot odour (bromodosis) is an embarrassing and perplexing condition mostly caused by bacteria of the Brevibacterium species. Essential oils are a credible option as an affordable treatment of odour and contribute towards antimicrobial efficacy. Therefore, this study sets out to investigate the antimicrobial activity of essential oil combinations against odour-causing bacteria. The broth microdilution method was used to investigate the antimicrobial activity of 119 essential oil combinations, and the fractional inhibitory index was calculated to determine the interactive profile. Combinations that resulted in synergy in 1 : 1 ratios were further evaluated in different concentrations, and isobolograms were plotted to determine the influence of the ratio on overall activity. Numerous combinations could be identified as having synergistic interactions against the Brevibacterium spp. and no antagonism was observed. The combination of Juniperus virginiana (juniper) and Styrax benzoin (benzoin) demonstrated synergy against all three Brevibacterium spp. tested and J. virginiana was the essential oil responsible for the majority of the synergistic interactions. The results reported here confirm the promising potential of the majority of these oils and selected combinations in treating and controlling bromodosis.

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Nisin/polyanion layer-by-layer films exhibiting different mechanisms in antimicrobial efficacy

RSC Advances ◽

10.1039/c9ra10135g ◽

2020 ◽

Vol 10 (17) ◽

pp. 10329-10337 ◽

Cited By ~ 2

Author(s):

Hanan Fael ◽

A. Levent Demirel

Keyword(s):

Antimicrobial Activity ◽

Controlled Release ◽

Multilayer Films ◽

Antimicrobial Efficacy ◽

Layer By Layer

Polyanion–nisin multilayer films exhibit antimicrobial activity by controlled release of nisin or as stable biofilm inhibiting coatings depending on polyanion.

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1217. Predicting the Efficacy of an Antimicrobial Surface Coating Utilizing X-Ray Fluorescence Spectroscopy (XRF)

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1080 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S437-S438

Author(s):

Parham Asgari ◽

Jie Fang ◽

Val Price ◽

Don DeClue ◽

Gavri Grossman ◽

...

Keyword(s):

Antimicrobial Activity ◽

Stainless Steel ◽

Fluorescence Spectroscopy ◽

Polymer Coating ◽

Test Organism ◽

Polymer Coatings ◽

Antimicrobial Efficacy ◽

X Ray ◽

Durable Polymer ◽

The Relationship

Abstract Background Contaminated surfaces are a critical risk factor for transmitting infectious disease. Current disinfection products provide short-term antimicrobial action; however, these surfaces can be re-contaminated within hours after cleaning. To address this limitation, long-lasting antimicrobial polymer coatings have been developed as an adjunct to traditional disinfecting and cleaning protocols. Due to the micro-scale thickness and transparency of the coating, confirmation of its presence on surfaces is difficult with conventional methods; therefore, this study explores a novel approach to measuring durable polymer coatings on stainless steel coupons to validate their presence and relative antimicrobial activity. Methods In this study, we utilized a hand-held X-ray fluorescence spectroscopy (XRF) analyzer to quantitatively evaluate the amount of antimicrobial polymer coating deposited on stainless steel test surfaces. Stainless steel surfaces with amounts of coating ranging from 0.12 to 3.60 mg/in.2 were analyzed for their XRF profile using a hand-held spectrometer. Additionally, the relationship between the XRF spectra and antimicrobial activity was evaluated using a modified version of an existing sanitization protocol for hard surfaces using Staphylococcus epidermidis as the test organism. Results Comparison of the amount of antimicrobial polymer coating (in mg) and the XRF values (photon count) revealed a calibration curve with a high degree of linearity (R2 = 0.993) especially for surfaces that had lower mass (Figure 1). In addition, the relationship between XRF values and antimicrobial efficacy also were found to be well-correlated with a logarithmic trend (R2 = 0.9308) (Figure 2). Conclusion The observed trends between coating mass, XRF value and antimicrobial efficacy suggests that these analytical techniques are viable options for determining the presence of invisible antimicrobial polymer coatings. Additionally, laboratory-based calibration curves based on XRF values can be used to predict the level of antimicrobial activity of surfaces that have been treated with polymer coatings. These findings suggest that the use of a hand-held XRF spectrometer can be a rapid and cost-effective method for assessing the presence and efficacy of polymer coatings. Disclosures All authors: No reported disclosures.

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Antimicrobial Activities of Hydrophobically Modified Poly(Acrylate) Films and Their Complexes with Different Chain Length Cationic Surfactants

Coatings ◽

10.3390/coatings9040244 ◽

2019 ◽

Vol 9 (4) ◽

pp. 244

Author(s):

Ioana Cătălina Gîfu ◽

Monica Elisabeta Maxim ◽

Ludmila Otilia Cinteza ◽

Marcela Popa ◽

Ludmila Aricov ◽

...

Keyword(s):

Antimicrobial Activity ◽

Cationic Surfactants ◽

Antimicrobial Properties ◽

Multilayer Films ◽

Antimicrobial Activities ◽

Layer By Layer ◽

Antimicrobial Efficiency ◽

Hydrophobically Modified ◽

Multilayered Systems ◽

The Stability

Multilayer films from hydrophobically modified poly(acrylic acid) (HMPA) and their complexes with cationic surfactants were successfully prepared using the layer-by-layer (LbL) method. Alkyl trimethylammonium bromide derivatives with various lengths of the hydrophobic chain (C10–C18) were used to interact with the HMPA polymer, generating highly hydrophobic domains in the films and contributing to the antimicrobial properties of the prepared coating. The antimicrobial efficiency against common pathogens such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans was investigated in relationship with the morphology and composition of the thin films. The wettability and roughness of the multilayered systems were evaluated using atomic force microscopy (AFM) and contact angle measurements. The effects of the microbial exposure on the surface properties of the prepared films were investigated in order to assess the stability of the HMPA-deposited multilayers and the durability of the antimicrobial activity. The hydrophobically modified films exhibited antimicrobial activity against the studied pathogens. The best efficiency was registered in the case of S. aureus, which showed an inhibition of growth up to 100% after 2 h. C. albicans proved to be less sensitive to the effect of the multilayers deposited from HMPA–surfactant complexes. These results suggest that HMPA and HMPA–surfactant complex LbL multilayer films can be used as promising materials in antimicrobial surface coatings with increased resistance to pathogens during exposure.

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75 Evaluating the in vitro release of essential oils from microparticles in simulated swine gastric and intestinal fluids and the essential oil stability in microparticles during feed pelleting process

Journal of Animal Science ◽

10.1093/jas/skz258.145 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 70-70

Author(s):

Janghan Choi ◽

Lucy Wang ◽

Joshua Gong ◽

Ludovic Lahaye ◽

Song Liu ◽

...

Keyword(s):

Essential Oil ◽

Essential Oils ◽

In Vitro Release ◽

Oil Stability ◽

Positive Effects ◽

Intestinal Fluids ◽

Gastric Fluids ◽

The Stability ◽

Vitro Release

Abstract Essential oils are defined as plant-derived natural bioactive compounds with positive effects on animal growth and health due to their antimicrobial and antioxidative properties. However, essential oils are very volatile, can evaporate rapidly and be rapidly absorbed in the upper gastrointestinal tract. In addition, due to their labile nature, the stability of essential oils during feed processing is often questionable, leading to variable final concentrations in feeds. Micro-encapsulation has become one of the most popular methods to deliver essential oils into the lower gut. The objective of the present study was double: 1) to validate and demonstrate the slow release of essential oils, such as thymol, micro-encapsulated in combination with organic acids in a matrix of triglycerides, in simulated swine gastric and intestinal fluids and 2) to evaluate the essential oil stability in the microparticles during feed pelleting process. In the in vitro release experiments, the microparticles were incubated in simulated gastric fluids for 2 hours and then the samples were incubated in simulated intestinal fluids for 0, 1, 2, 3, 4, 6, 8, 10, and 24 hours at 39°C. In the pelleting experiment, a wheat-corn basal diet with 2 kg of micro-encapsulated product was formulated and pelleted. The thymol content in the samples was analyzed by gas chromatography with flame-ionization detection. The results showed that 27.65% thymol was released in simulated gastric fluids and the rest of thymol was progressively released in intestinal fluids until completion, which was achieved by 24 hours. The thymol concentration was not significantly different between the mash feeds and pelleted feeds (P > 0.05). In conclusion, the micro-encapsulated organic acid and essential oil product was able to maintain the stability of thymol under a commercial pelleting process and allow a slow and progressive release of its active ingredients as thymol in simulated digestive fluids.

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Leptospermum scoparium (Mānuka) and Cryptomeria japonica (Sugi) Leaf Essential Oil Seasonal Chemical Variation and Their Effect on Antimicrobial Activity

10.20944/preprints202008.0623.v1 ◽

2020 ◽

Author(s):

Kyung Whan Bang ◽

Gillian Lewis ◽

Silas G. Villas-Boas

Keyword(s):

Antimicrobial Activity ◽

Seasonal Variation ◽

Essential Oil ◽

Essential Oils ◽

Cryptomeria Japonica ◽

Consumer Products ◽

Antimicrobial Efficacy ◽

Future Application ◽

Chemical Variation ◽

Leptospermum Scoparium

This study evaluated the antimicrobial activity of Leptospermum scoparium (Mānuka) and Cryptomeria japonica (Sugi) essential oils and assessed the effect of seasonal chemical variation on the oils’ antimicrobial efficacies. Plate based assays were conducted to elucidate the oils’ spectrum of in vitro antimicrobial activity and to determine the oils’ minimum inhibitory concentrations (MIC) as a measure of antimicrobial efficacy. Gas chromatography – mass spectrometry was adopted to chemically profile oils distilled in different seasons. The resultant compositional information in conjunction with MIC data was used to evaluate the effect of seasonal variation on the oils’ antimicrobial efficacy. Both Mānuka and Sugi essential oils were active against all classes of target microorganisms. However, limited activity was observed against Gram-negative bacteria. The oils displayed consistent chemotypic characteristics regardless of the time of distillation. Nonetheless, there were quantitative differences in compound abundance in both essential oils. Significant differences in the MIC of Sugi essential oil was observed against target microorganisms as a result of seasonal variation in constituent abundances while Mānuka essential oil’s antimicrobial efficacy was unaffected. This study demonstrates that seasonal chemical variation is an important quality assurance parameter to consider for future application of essential oils as antimicrobial agents in consumer products.

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