In vitro evaluation of nebulized eucalyptol nano-emulsion formulation as a potential COVID-19 treatment

The comprehensive review of eucalyptol: synthesis, metabolism, and therapeutic applications in disease treatment

BACKGROUND

Eucalyptol (1,8-cineole), a naturally occurring monoterpenoid compound, is ubiquitously distributed across plant, animal, and microbial organisms. This bioactive molecule demonstrates significant therapeutic potential for various neurological and respiratory disorders, including cancer, epilepsy, and tracheitis, attributable to its potent antioxidant, anti-inflammatory, and antimicrobial properties.

SCOPE AND THRUST

The present review systematically examines the biosynthetic pathways and metabolic routes of eucalyptol, while elucidating its molecular mechanisms underlying microbial inhibition. We comprehensively summarize its principal therapeutic pathways in major disease interventions, with particular emphasis on its multi-target pharmacological actions. Furthermore, this analysis addresses potential toxicological concerns associated with eucalyptol application and discusses emerging strategies utilizing biological agents for active enhancement.

CONCLUSION AND SIGNIFICANCE

This comprehensive evaluation not only enhances our understanding of eucalyptol's therapeutic mechanisms but also provides critical insights for its development as a promising phytopharmaceutical agent in clinical practice.

The Current Status, Hotspots, and Development Trends of Nanoemulsions: A Comprehensive Bibliometric Review

Nanoemulsions, which are characterized by their nanometer-scale droplets, have gained significant attention in different fields, such as medicine, food, cosmetics, and agriculture, because of their unique properties. With an increasing number of countries engaging in research on nanoemulsions, interest in their properties, preparation methods, and applications has increased. Hence, tracing the relevant research on nanoemulsions published in the past ten years on a global scale, by conducting data mining and visualization analysis on a sufficiently large text dataset through bibliometrics, sorting out and summarizing certain indicators, the development history, research status and research hotspots in the field of nanoemulsions can be clearly revealed, providing reference value and significance for subsequent research. This bibliometric review examines the research landscape of nanoemulsions from 2013-2023 via the SCI-E and SSCI databases, providing insights into the current status, hotspots, and future trends of this field. To offer a comprehensive overview, this analysis includes publication counts, author keywords, institutional contributions, research areas, prolific authors, highly cited papers and hot research papers. The findings reveal that China led in nanoemulsions research, followed by USA, India, and Brazil, with the University of Massachusetts emerging as a key player with the highest average number of citations per article (ACPP) and h-index. Food Chemistry, Pharmaceutics, and the Journal of Drug Delivery Science and Technology are among the top journals publishing in this area. Chemistry, pharmacology, and pharmacy emerged as the primary research domains, with McClements DJ as the most prolific and influential author. In keyword analysis, essential oil nanoemulsions are currently the main preparation direction, and various characteristics of nanoemulsions, such as their bioavailability, stability, biocompatibility, and antioxidant and antibacterial properties, have also been studied extensively. Research hotspots are focused mostly on the development of new applications and technologies for nanoemulsions.

Eucalyptus Essential Oil Inhibits Cell Infection by SARS-CoV-2 Spike Pseudotyped Lentivirus

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a public health concern due to infections with new SARS-CoV-2 variants. Therefore, finding effective preventive and therapeutic treatments against all SARS-CoV-2 variants is of great interest. In this study, we examined the capacity of eucalyptus essential oil (EEO) and eucalyptol (EOL) to prevent SARS-CoV-2 infection, using as a model SARS-CoV-2 Spike pseudotyped lentivirus (SARS-CoV-2 pseudovirus) and 293T cells transfected with human angiotensin-converting enzyme 2 (hACE2-293T cells). First, we determined the cytotoxicity of EEO and EOL using the MTT colorimetric assay, selecting non-cytotoxic concentrations ≤ 0.1% (v/v) for further analysis. Subsequently, we evaluated the capacity of EEO and EOL in cell cultures to preclude infection of hACE2-293T cells by SARS-CoV-2 pseudovirus, using a luciferase-based assay. We found that EEO and EOL significantly reduced SARS-CoV-2 pseudovirus infection, obtaining IC50 values of 0.00895% and 0.0042% (v/v), respectively. Likewise, EEO and EOL also reduced infection by vesicular stomatitis virus (VSV) pseudovirus, although higher concentrations were required. Hence, EEO and EOL may be able to inhibit SARS-CoV-2 infection, at least partially, through a Spike-independent pathway, supporting the implementation of aromatherapy with these agents as a cost-effective antiviral measure.

Evaluation of the effects of a dasatinib-containing, self-emulsifying, drug delivery system on HT29 and SW420 human colorectal carcinoma cells, and MCF7 human breast adenocarcinoma cells

Background/Aim

Dasatinib (DS), a second-generation tyrosine kinase inhibitor, functions as a multi-target small-molecule drug via targeting various tyrosine kinases involved in neoplastic cell growth. DS inhibits cancer cell replication and migration, and induces tumor cell apoptosis in a variety of solid tumors. However, it is poorly soluble in water under some pH values. Therefore, the development of a DS-containing, self-emulsifying, drug delivery system (SeDDs) could help overcome these problems in treating cancer cells.

Methods

Various SeDD formulations loaded with DS were developed with isopropyl myristate (oil phase), Labrafil (surfactant), and polyethylene glycol (co-surfactant). The physicochemical properties of the formulations were assessed according to droplet size, encapsulation efficiency, and in vitro drug release. The cytotoxicity of the formulations on the cancer cell lines HT29 and SW420 (human colorectal carcinoma), and MCF7 (human breast adenocarcinoma), in addition to MRC5 normal human fetal lung fibroblasts, was evaluated to assess selectivity.

Results

The DS-SeDD formulation showed favorable particle size, encapsulation efficiency, and in vitro drug release. The anti-cancer potency of DS-SeDDs had greater cytotoxicity effects than pure DA on the three cancer cell lines, MCF7, HT29, and SW420l.

Conclusion

The developed DS-SeDD formulations may potentially be an effective sustained drug delivery method for cancer therapy.

Evaluating dasatinib nanocarrier: Physicochemical properties and cytotoxicity activity on cancer cells

Objective

Dasatinib-(DAS) is a tyrosine kinase inhibitor usually used to treat leukemia. However, DAS is a poorly water-soluble drug. Therefore, oil-in-water emulsions were used for DAS to enhance its solubility and cancer treatment efficacy. This study aims to develop an appropriate DAS nanoemulsion (NE) that can overcome the issue of DAS solubility and provide an effective anticancer effect.

Methods

Spherical particles dispersed in an aqueous media approach within an oily phase (oleic acid, Kolliphor RH40, and dipropylene glycol) were used to formulate DAS-NE using high-energy methods. Different formulas were developed and an appropriate formula was analyzed to identify its physicochemical properties. Raw DAS and nonformula cytotoxicity were evaluated through MTT assay against three cancer cell lines, MCF7 (human breast adenocarcinoma), HT29, and SW480 (human colorectal carcinomas), in addition to MRC5 (Normal human fetal lung fibroblast).

Results

Different DAS-NEs (1-7) have been developed successfully. Formulas had a droplet size of a diameter ranging from 84.167 ± 10.178 nm to 273.433 ± 45.267 nm. The drug content of the appropriate formula (DAS-NE3) was found to be 83.2%. The drug release result of DAS-NE3 when compared to raw DAS was about 58%, falling to 13% after 24 h. The DAS-NE3 showed cytotoxicity against the three cancer cells below 26.11 μM but showed 30-fold significantly increased selectivity against MRC5 normal cells compared to that of raw DAS.

Conclusion

This study shows that the DAS-NE3 formula may provide a potentially effective and sustained drug delivery for cancer treatment. This provides valuable information to the scientific community and the pharmaceutical industry.

Comparative Cytotoxicity of Menthol and Eucalyptol: An In Vitro Study on Human Gingival Fibroblasts

The aim of this study was to assess the influence of eucalyptol and menthol on the cell viability, migration, and reactive oxygen species production of human gingival fibroblasts (GFs) in vitro. Three different concentrations of eucalyptol and menthol were prepared following ISO 10993-5 guidelines (1, 5, and 10 mM). GFs were isolated from extracted teeth from healthy donors. The following parameters were assessed: cell viability via MTT, Annexin-V-FITC and 7-AAD staining, and IC50 assays; cell migration via horizontal scratch wound assay; and cell oxidative stress via reactive oxygen species assay. Data were analyzed using one-way ANOVA and Tukey's post hoc test. Statistical significance was established at p < 0.05. Eucalyptol and Menthol exhibited high cytotoxicity on gingival fibroblasts, as evidenced by cytotoxicity assays. Eucalyptol showed lower levels of cytotoxicity than menthol, compared to the control group. The cytotoxicity of the tested substances increased in a concentration-dependent manner. The same occurred in a time-dependent manner, although even 10 min of exposure to the tested substances showed a high cytotoxicity to the GFs. Commercially available products for oral application with these substances in their composition should be tested for cytotoxicity before their use.

Updated insight into the characterization of nano-emulsions

INTRODUCTION

In most of the studies, nano-emulsion characterization is limited to their size distribution and zeta potential. In this review, we present an updated insight of the characterization methods of nano-emulsions, including new or unconventional experimental approaches to explore in depth the nano-emulsion properties.

AREA COVERED

We propose an overview of all the main techniques used to characterize nano-emulsions, including the most classical ones, up to in vitro, ex vivo and in vivo evaluation. Innovative approaches are then presented in the second part of the review that presents innovative, experimental techniques less known in the field of nano-emulsion such as the nanoparticle tracking analysis, small-angle X-ray scattering, Raman spectroscopy, and nuclear magnetic resonance. Finally, in the last part we discuss the use of lipophilic fluorescent probes and imaging techniques as an emerging tool to understand the nano-emulsion droplet stability, surface decoration, release mechanisms, and in vivo fate.

EXPERT OPINION

This review is mostly intended for a broad readership and provides key tools regarding the choice of the approach to characterize nano-emulsions. Innovative and uncommon methods will be precious to disclose the information potentially reachable behind a formulation of nano-emulsions, not always known in first intention and with conventional methods.