Microbiological safety of essential oils used in complementary therapies and the activity of these compounds against bacterial and fungal pathogens

Polymer nanoparticles containing essential oils: new options for mosquito control

Mosquitoes (Diptera: Culicidae) are vectors of important parasites and pathogens causing death, poverty and social disability worldwide. The overuse of synthetic insecticides to control mosquito vectors lead to resistance, adverse environmental effects and high operational costs. Therefore, the development of eco-friendly control tools is an important public health challenge. In this study, two different essential oils (EO) (geranium, Geranium maculatum, and bergamot, Citrus bergamia) loaded polymeric nanoparticle (PN) were elaborated using polyethylene glycol (PEG) and chitosan (Qx) as the polymeric matrix/coating. In addition, the mosquito larvicidal acute and residual activity of the PN was evaluated on Culex pipiens pipiens. The physicochemical characterization of PN revealed that PEG-PN had sizes <255 nm and encapsulation efficiency between 68 and 77%; Qx-PN showed sizes <535 nm and encapsulation efficiency between 22 and 38%. From the toxicological test, it was observed that Qx-PN produced higher acute and residual activity than PEG-PN. Overall, this study highlights that polymer nanoparticles containing essential oil are a promising source of eco-friendly mosquito larvicidal products.

Plant essential oils and their constituents in coping with multidrug-resistant bacteria

Antibiotic resistance is documented to be a serious problem that affects the choice of appropriate antibiotic therapy and increases the probability of unfavorable infection outcome. One of the proposed methods to cope with multidrug-resistant (MDR) bacteria is the use of alternative antibacterial treatments, which include natural antimicrobial substances such as plant essential oils (EOs). The aim of the present article is to review published studies on the activity of EOs and their constituents against MDR bacteria and to formulate perspectives for the future. In general, published studies indicate that EOs can be used as effective antiseptics against many species, including MDR bacteria, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, resistant isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae and others; certain EOs may potentiate the effectiveness of antibiotics against MDR bacteria; EOs can be synergistic with bacteriophages; and polymeric nanoparticles can be used for delivery of EOs and enhancement of their activity at the site of infection.

Study of the aerosol fragrances of eugenol derivatives in Cananga odorata using diffuse reflectance infrared Fourier transform spectroscopy and gas chromatography

The purpose of this study was to develop and test a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) method, a fast and non-destructive method without extraction, and compare it with the standard gas chromatography (GC) method currently used. A micro-orifice uniform deposit impactor (MOUDI) was used to sample all the size distributions of the aerosol particles of essential oils to investigate the relation between size distributions and the indoor concentration distributions of ylang essential oils. Correlation coefficients for DRIFTS and GC were 0.9904, 0.9910, 0.9913, and 0.9983 for eugenol, isoeugenol, methyl ether, and eugenyl acetate, respectively. The results showed that the concentrations of the four eugenol derivatives of smoke were approximately three times higher than those of mist. Additionally, the major size distributions of aerosol were 0.19 microm and 1.8 microm for the smoke and mist methods, respectively. Because these two methods produce similar results, DRIFTS is a practical method for assessing these fragrances in aerosols.

Antifungal effect of various essential oils againstCandidaalbicans. Potentiation of antifungal action of amphotericin B by essential oil fromThymus vulgaris

The antifungal effect of the essential oil from Satureja montana L., Lavandula angustifolia Mill., Lavandula hybrida Reverchon, Syzygium aromaticum (L.) Merril and Perry, Origanum vulgare L., Rosmarinus officinalis L. and six chemotypes of Thymus vulgaris L. on Candida albicans growth were studied. The most efficiency was obtained with the essential oil from Thymus vulgaris thymol chemotype (MIC 80% = 0.016 microL/mL and Kaff = 296 microL/mL). The presence in the culture medium of essential oil from Thymus vulgaris thymol chemotype (0.01, 0.1, 0.2, 0.3 microg/mL) and amphotericin B involved a decrease of the MIC 80% of amphotericin B. In contrast, the combination of amphotericin B and low concentrations (0.00031-0.0025 microg/mL) of essential oil was antagonistic. The strongest decrease (48%) of the MIC 80% was obtained with medium containing 0.2 microL/mL of essential oil. These results signify that the essential oil of Thymus vulgaris thymol chemotype potentiates the antifungal action of amphotericin B suggesting a possible utilization of this essential oil in addition to antifungal drugs for the treatment of mycoses.

Aromatherapy practice in nursing: literature review

BACKGROUND

The use of aromatherapy in nursing care continues to be popular in many settings. Most of the nursing literature relates to the use of essential oils in low doses for massage or use of the oils as environmental fragrances. Information from the wider literature may add to the evidence base for use of this therapy in nursing.

AIM

This paper reports a literature relating to the use of aromatherapy by nurses and critically evaluates the evidence to support this practice.

METHOD

Medline, CINAHL, MANTIS and EBSCO Host databases were searched for papers related to use of essential oils and/or aromatherapy. Papers were also obtained through cross-checking of reference lists. A total of 165 articles have been included in this review. Nursing papers were published since 1990 were included, but some references from 1971 onwards relating to scientific research conducted on essential oils were also included. These remain valuable as they are probably the only reference available for a specific oil or property, or show the development of knowledge in this area. Papers were excluded if they consisted only of brief case studies presented in abstract form. The review covers key professional issues and the principal areas of clinical practice where aromatherapy is used.

FINDINGS

Despite calls for more research in the 1980s and 1990s, there is still little empirical evidence to support the use of aromatherapy in nursing practice beyond enhancing relaxation. Its popularity needs to be balanced against the potential risks related to allergies, safety and inappropriate use by inexperienced users.

CONCLUSIONS

There is great potential for more collaborative research by nurses to explore the clinical applications in greater detail and to move beyond the low dose paradigm of application of essential oils.