The use of chemometric modelling to determine chemical composition-antimicrobial activity relationships of essential oils used in respiratory tract infections

Antifungal Properties of Essential Oils Derived from the Genus Cymbopogon: A Systematic Review

Essential oils (EOs) are products of secondary metabolism with recognized organoleptic characteristics and biological properties. Recently, there has been a growing demand for EOs in the national and international market, mainly due to the recognition of their use as complementary medicine practices, and the increased use in the industries of pharmaceutics, cosmetics, well-being, veterinary and agroecology, boosting the productive sector. In this context, EOs from grasses of the Cymbopogon (Poaceae) are promising sources of bioactive compounds, due to their recognized biological properties, such as anti-inflammatory, antibacterial, antifungal, antidiabetic, repellent, and larvicide. Thus, the present study aims to carry out a review of the scientific literature of the main works related to the evaluation of the antifungal action of essential oils extracted from plants of the Cymbopogon genus, compiling the species that showed the best results and relating them to their main chemical constituents. This review covers the following species: C. citratus, C. flexuosus, C. winterianus, C. martinii, C. nardus, C. giganteus, C. schoenanthus, C. khasans, and C. proximus. Among them, C. citratus was the most assessed, being associated with the vast majority of studies (61.9 %), and it was also the species that showed the best results in terms of MIC.

Optimizing the Antimicrobial Synergism of Melaleuca alternifolia (Tea Tree) Essential Oil Combinations for Application against Respiratory Related Pathogens

Antimicrobial research into the use of Melaleuca alternifolia essential oil has demonstrated broad-spectrum activity; however, much of the research published focuses on identifying the potential of this essential oil individually, rather than in combination for an enhanced antimicrobial effect. This study aimed to determine the antimicrobial activity of four essential oil combinations, all inclusive of M. alternifolia, against nine pathogens associated with the respiratory tract. The minimum inhibitory concentration assay was used to determine the antimicrobial activity of four essential oil combinations, M. alternifolia in combination with Cupressus sempervirens, Origanum majorana, Myrtus communis, and Origanum vulgare essential oils. The interactions between essential oil combinations were analyzed using isobolograms and SynergyFinder 2.0 software to visualize the synergistic potential at varied ratios. The antimicrobial activity of the different combinations of essential oils all demonstrated the ability to produce an enhanced antimicrobial effect compared to the essential oils when investigated independently. The findings of this study determined that isobolograms provide a more in-depth analysis of an essential oil combination interaction; however, the value of that interaction should be further quantified using computational modelling such as SynergyFinder. This study further supports the need for more studies where varied ratios of essential oils are investigated for antimicrobial potential.

Essential oils as valuable feed additive: A narrative review of the state of knowledge about their beneficial health applications and enhancement of production performances in poultry

New research has begun to develop safe and effective alternatives to feed-antibiotics as growth enhancers in response to mounting pressure on the poultry sector to do so. There is a significant demand for poultry products all across the world right now. To achieve this goal, key performance indicators are optimized, such as the rate of chicken growth, the amount of feed used, and the health of the flock as a whole. As a result of this growing need, various alternatives to antibiotics have entered the market. New approaches are desperately needed to keep poultry productivity and efficiency at a high level in the face of mounting pressure to limit the use of antibiotics. Recent years have seen an uptick in interest in the potential of aromatic plant extracts as growth and health boosters in poultry. The great majority of plants' positive effects are accounted for by essential oils (EOs) and other secondary metabolites. EOs have been proven to promote digestive secretion production, improve blood circulation, exert antioxidant qualities, reduce levels of dangerous microbes, and maybe improve the immune status of poultry. EOs are often believed to be safe, non-toxic alternatives because they are all-natural, chemical-free, and devoid of potentially harmful deposits. EOs are extracted from plants, and while there are thousands of them, only approximately 300 have been deemed to have significant commercial value. Many different types of bacteria, viruses, fungi, and parasites are negatively affected by EOs in multiple studies conducted both in vitro and in vivo. The review covers the fundamentals of EOs, their anti-oxidant and immunomodulatory capabilities, their growth-promoting benefits, and their effectiveness against numerous diseases in poultry.

Potential effects of essential oils in safeguarding the health and enhancing production performance of livestock animals: The current scientific understanding

The food sector competes in a cutthroat environment, and it constantly struggles to maintain or even grow its market share. For customer confidence and consumption to remain strong, consistent animal products are needed. The qualitative attributes of the derived goods appear to be improved by the addition of bioactive substances to food, such as essential oils (EOs), and consumers are shielded from the impacts of bacterial and oxidative deterioration. Due to the current controversy surrounding synthetic chemicals and their alleged carcinogenic potential, a substantial study has been done to find effective and safe substitutes. Aromatic plants and the corresponding EOs from them are considered natural products and are typically employed in ruminant nutrition. Since dietary supplementation has been demonstrated to be an easy and practical method to successfully suppress oxidative processes or microbial deterioration at their localized sites, the addition of EOs in animal diets is now becoming a regular practice. However, there is just a little amount of evidence supporting the notion that these compounds may improve nutrient absorption and gastrointestinal health. Additionally, a variety of factors affect how well EOs works in animal diets. These variables can be, on the one hand, the erratic composition, and the many additions to the diet, and, on the other hand, erratic animal genetic elements. Maximizing the use of EOs and creating high-quality products require a deeper understanding of the composition and activity of the gastrointestinal tract microbiota. Numerous EOs contain bioactive substances with the potential to serve as multifunctional feed supplements for animals, with impacts on growth performance, the digestive system, the growth of pathogenic bacteria, and lipid oxidation, among others. To establish their regular use in animal production and to determine their precise mechanism of action, more research is required. The potential advantages of EOs for livestock health and production are highlighted in the current article.

Chemometric Investigation and Antimicrobial Activity of Salvia rosmarinus Spenn Essential Oils

To ensure the better production and sustainable management of natural resources, a chemometric investigation was conducted to examine the effect of cooperative and harvesting periods on the crop yields and chemical compositions of Salvia rosmarinus Spenn essential oils in the Oriental region of Morocco. The samples were collected from three cooperatives over nine time periods from January 2018 to April 2019. The chemical composition of Salvia rosmarinus Spenn essential oils was analyzed by gas chromatography coupled with mass spectrometry. The data from this study were processed by multivariate analyses, including principal component analysis (PCA) and hierarchical cluster analysis (HCA). The disc diffusion technique and a determination of the minimal inhibitory concentration were performed to study the antibacterial properties of the oils. Statistical analysis showed that the cooperative and harvest period have a significant effect on yields. The highest yield of essential oil was recorded in April 2019 at cooperative C1. The PCA and the HCA results were divided into two groups: Group A for the summer season and group B for the winter season. The samples collected during summer were characterized by a high amount of 1,8-cineole component and a high yield of essential oil, whereas the samples collected during winter were qualified by a high amount of α-pinene component and a low yield of essential oil. The antibacterial activity of Salvia rosmarinus Spenn essential oils showed that Mycobacterium smegmatis ATCC23857 and Bacillus subtilis ATCC 23857 are the most susceptible strains, stopping growth at 1/500 (v/v). The least susceptible strain is Escherichia coli ATCC25922, with an MIC value corresponding to 1/250 (v/v). The findings of this study could have a positive economic impact on the exploitation of rosemary in the Oriental region, especially during the best harvest periods, as they indicate how to obtain the best yields of oils richest in 1,8-cineole and α-pinene chemotypes.

Essential Oil Blends: The Potential of Combined Use for Respiratory Tract Infections

This study investigated the potential efficacy of 369 commercial essential oil combinations for antimicrobial, anti-toxic and anti-inflammatory activity with the aim of identifying synergy among essential oils commonly used in combination by aromatherapists for respiratory purposes. Essential oil combinations were assessed for their antimicrobial activities using a panel of Gram-positive, Gram-negative, and yeast strains associated with respiratory tract infections. The antimicrobial activity was measured by determining the minimal inhibitory concentration (MIC) of microbial growth. The fractional inhibitory concentration index (ΣFIC) was calculated to determine the antimicrobial interactions between the essential oils in the combination. The toxicity of the essential oil combinations was tested in vitro using the brine shrimp lethality assay, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on RAW 264.7 mouse macrophage cells and A549 lung cancer cell lines. In addition, an inflammatory response was evaluated measuring nitric oxide production. The essential oils, when in combination, demonstrated an increased antimicrobial effect, a reduction in toxicity and provided improved anti-inflammatory outcomes. Five distinct combinations [Cupressus sempervirens (cypress) in combination with Melaleuca alternifolia (tea tree), Hyssopus officinalis (hyssop) in combination with Rosmarinus officinalis (rosemary), Origanum marjorana (marjoram) in combination with M. alternifolia, Myrtus communis (myrtle) in combination with M. alternifolia and Origanum vulgare (origanum) in combination with M. alternifolia] were found to be the most promising, demonstrating antimicrobial activity, reduced cytotoxicity and improved anti-inflammatory effects. With the increased prevalence of respiratory tract infections and the growing antimicrobial resistance development associated with antimicrobial treatments, this study provides a promising complementary alternative for the appropriate use of a selection of essential oil combinations for use in the respiratory tract.