Essential Oil Nanoemulsion Hydrogel with Anti-Biofilm Activity for the Treatment of Infected Wounds.

The formation of a bacterial biofilm on an infected wound can impede drug penetration and greatly thwart the healing process. Thus, it is essential to develop a wound dressing that can inhibit the growth of and remove biofilms, facilitating the healing of infected wounds. In this study, optimized eucalyptus essential oil nanoemulsions (EEO NEs) were prepared from eucalyptus essential oil, Tween 80, anhydrous ethanol, and water. Afterward, they were combined with a hydrogel matrix physically cross-linked with Carbomer 940 (CBM) and carboxymethyl chitosan (CMC) to prepare eucalyptus essential oil nanoemulsion hydrogels (CBM/CMC/EEO NE). The physical-chemical properties, in vitro bacterial inhibition, and biocompatibility of EEO NE and CBM/CMC/EEO NE were extensively investigated and the infected wound models were proposed to validate the in vivo therapeutic efficacy of CBM/CMC/EEO NE. The results showed that the average particle size of EEO NE was 15.34 ± 3.77 nm with PDI ˂ 0.2, the minimum inhibitory concentration (MIC) of EEO NE was 15 mg/mL, and the minimum bactericidal concentration (MBC) against S. aureus was 25 mg/mL. The inhibition and clearance of EEO NE against S. aureus biofilm at 2×MIC concentrations were 77.530 ± 7.292% and 60.700 ± 3.341%, respectively, demonstrating high anti-biofilm activity in vitro. CBM/CMC/EEO NE exhibited good rheology, water retention, porosity, water vapor permeability, and biocompatibility, meeting the requirements for trauma dressings. In vivo experiments revealed that CBM/CMC/EEO NE effectively promoted wound healing, reduced the bacterial load of wounds, and accelerated the recovery of epidermal and dermal tissue cells. Moreover, CBM/CMC/EEO NE significantly down-regulated the expression of two inflammatory factors, IL-6 and TNF-α, and up-regulated three growth-promoting factors, TGF-ß1, VEGF, and EGF. Thus, the CBM/CMC/EEO NE hydrogel effectively treated wounds infected with S. aureus, enhancing the healing process. It is expected to be a new clinical alternative for healing infected wounds in the future.

In Vitro Cytotoxicity and Apoptotic Assay of Eucalyptus globulus Essential Oil in Colon and Liver Cancer Cell Lines.

PURPOSE: Toxic effects of vegetables have been the subject of numerous investigations in recent years. Eucalyptus globulus of the Myrtaceae family has been traditionally used in the treatment of various infectious disorders. This study aims to assay the potential anticancer effect of Eucalyptus globulus essential oil, in vitro, and compare its cytotoxic effects on cancerous and non-cancerous cell lines. METHODS: The cytotoxicity of the Eucalyptus globulus essential oil was evaluated in colon cancer cell line SW48, liver cancer cell line HepG2, HEK293t, and skin fibroblast using the MTT assay. We used 5-FU as the control treatment for cancer. The essential oil was diluted by phosphate buffer saline in cell culture. RESULTS: Eucalyptus globulus essential oil with the concentration of 0.01% did not reduce the cell viability of SW48 (IC50 = 0.2%) and fibroblast cells (IC50 = 5%) after a 48-h treatment period. Eucalyptus globulus essential oil did not also exhibit any toxic effects on HEK293t and HEPG2 cell lines, except in high dose (0.5%) with IC50 = 0.2% for both of the cell lines. CONCLUSION: Eucalyptus essential oil showed some side effects and might not be safe to use for treatment at high doses (0.5% and 5%). Moreover, the findings of the present study show that eucalyptus essential oil suppressed the proliferation of human colon cancer cells by inducing apoptosis. Eucalyptus essential oil might be a good candidate for the treatment of colon cancer.

Antiviral Activities of Eucalyptus Essential Oils: Their Effectiveness as Therapeutic Targets against Human Viruses.

Given the limited therapeutic management of infectious diseases caused by viruses, such as influenza and SARS-CoV-2, the medicinal use of essential oils obtained from Eucalyptus trees has emerged as an antiviral alternative, either as a complement to the treatment of symptoms caused by infection or to exert effects on possible pharmacological targets of viruses. This review gathers and discusses the main findings on the emerging role and effectiveness of Eucalyptus essential oil as an antiviral agent. Studies have shown that Eucalyptus essential oil and its major monoterpenes have enormous potential for preventing and treating infectious diseases caused by viruses. The main molecular mechanisms involved in the antiviral activity are direct inactivation, that is, by the direct binding of monoterpenes with free viruses, particularly with viral proteins involved in the entry and penetration of the host cell, thus avoiding viral infection. Furthermore, this review addresses the coadministration of essential oil and available vaccines to increase protection against different viruses, in addition to the use of essential oil as a complementary treatment of symptoms caused by viruses, where Eucalyptus essential oil exerts anti-inflammatory, mucolytic, and spasmolytic effects in the attenuation of inflammatory responses caused by viruses, in particular respiratory diseases.

A strategy of rapidly screening out herbicidal chemicals from Eucalyptus essential oils.

BACKGROUND: To enhance discovering efficiency of new herbicidal compounds, a strategy for rapidly screening out strongly herbicidal chemical components from natural resources is necessary. RESULTS: Seventeen essential oils selected from 14 Eucalyptus species and hybrids were evaluated for their herbicidal activities on annual ryegrass. A feasible strategy was established for rapidly pinpointing the chemicals contributing to strong herbicidal activities without the process of isolation and purification of individual compounds. This strategy was based on gas chromatography-mass spectrometry (GC-MS) coupled with principal component analysis (PCA) and verified by the bioassay results using several individual compounds. Two strong herbicidal compounds trans-pinocarveol and α-terpineol were screened out using the strategy. The strong herbicidal activity of trans-pinocarveol was discovered for the first time. CONCLUSION: The established strategy of screening herbicidal compounds from natural resources is simple, feasible and reliable. © 2019 Society of Chemical Industry.

Essential oil-loaded lipid nanoparticles for wound healing.

Chronic wounds and severe burns are diseases responsible for severe morbidity and even death. Wound repair is a crucial process and tissue regeneration enhancement and infection prevention are key factors to minimize pain, discomfort, and scar formation. The aim of this work was the development of lipid nanoparticles (solid lipid nanoparticles and nanostructured lipid carriers [NLC]), to be loaded with eucalyptus or rosemary essential oils and to be used, as medical devices, to enhance healing of skin wounds. Lipid nanoparticles were based on natural lipids: cocoa butter, as solid lipid, and olive oil or sesame oil, as liquid lipids. Lecithin was chosen as surfactant to stabilize nanoparticles and to prevent their aggregation. The systems were prepared by high shear homogenization followed by ultrasound application. Nanoparticles were characterized for physical-chemical properties, bioadhesion, cytocompatibility, in vitro proliferation enhancement, and wound healing properties toward normal human dermal fibroblasts. Antimicrobial activity of nanoparticles was evaluated against two reference microbial strains, one of Staphylococcus aureus, the other of Streptococcus pyogenes. Finally, the capability of nanoparticles to promote wound healing in vivo was evaluated on a rat burn model. NLC based on olive oil and loaded with eucalyptus oil showed appropriate physical-chemical properties, good bioadhesion, cytocompatibility, in vitro proliferation enhancement, and wound healing properties toward fibroblasts, associated to antimicrobial properties. Moreover, the in vivo results evidenced the capability of these NLC to enhance the healing process. Olive oil, which is characterized by a high content of oleic acid, proved to exert a synergic effect with eucalyptus oil with respect to antimicrobial activity and wound repair promotion.