Héloïse Côté

Plant-derived products, particularly essential oils, represent a promising source of antiviral scaffolds. Although Populus balsamifera L. has been traditionally used to manage respiratory ailments and infections, the antiviral potential of its bud essential oil remains unexplored. In this study, we evaluated the in vitro antiviral cytoprotective activity of P. balsamifera bud essential oil and its major constituents against HCoV-OC43, a human betacoronavirus associated with seasonal respiratory infections, using a cell-based cytoprotection assay. The assay reliably detected the activity of reference antivirals, including chloroquine (EC₅₀ = 0.11 ± 0.01 µg/mL), molnupiravir, and fluvoxamine, supporting its suitability for antiviral screening. Under these conditions, P. balsamifera bud essential oil exhibited strong cytoprotective activity, with an EC₅₀ of 3.3 ± 0.5 µg/mL. Chemical analysis revealed a sesquiterpene-rich composition. Two major constituents, α-bisabolol and nerolidol, also showed marked cytoprotection, with EC₅₀ values of 2.7 ± 0.3 µg/mL and 2.6 ± 0.4 µg/mL, respectively, supporting their contribution to the overall activity of the oil. To our knowledge, this study provides the first experimental evidence of antiviral cytoprotective activity of P. balsamifera bud essential oil against a human coronavirus and identifies α-bisabolol and nerolidol as active compounds in this model.

The use of growth-promoting antibiotics in livestock faces increasing scrutiny and opposition due to concerns about the increased occurrence of antibiotic-resistant bacteria. Alternative solutions are being sought, and plants of Lamiaceae may provide an alternative to synthetic antibiotics in animal nutrition. In this study, we extracted essential oil from Monarda didyma, a member of the Lamiaceae family. We examined the chemical composition of the essential oil and then evaluated the antibacterial, antioxidant, and anti-inflammatory activities of M. didyma essential oil and its main compounds in vitro. We then evaluated the effectiveness of M. didyma essential oil in regard to growth performance, feed efficiency, and mortality in both mice and broilers. Carvacrol (49.03%) was the dominant compound in the essential oil extracts. M. didyma essential oil demonstrated antibacterial properties against Escherichia coli (MIC = 87 µg·mL⁻¹), Staphylococcus aureus (MIC = 47 µg·mL⁻¹), and Clostridium perfringens (MIC = 35 µg·mL⁻¹). Supplementing the diet of mice with essential oil at a concentration of 0.1% significantly increased body weight (+5.4%) and feed efficiency (+18.85%). In broilers, M. didyma essential oil significantly improved body weight gain (2.64%). Our results suggest that adding M. didyma essential oil to the diet of broilers offers a potential substitute for antibiotic growth promoters.

Background: Tanacetum vulgare L. (Asteraceae) is a perennial herb that has been used to treat multiple ailments. Regional variability of the chemical composition of T. vulgare essential oils is well-known. Despite these regional chemotypes, most relevant studies did not analyze the complete chemical composition of the T. vulgare essential oil and its constituents in relation to their biological activities. Here, we assess the anti-inflammatory, antioxidant, antibacterial, and cytotoxic activities of T. vulgare collected from northern Quebec (Saguenay-Lac-St-Jean), Canada. Methods: Essential oil was extracted from plants by steam distillation and analyzed using GC-FID. Biological activities of essential oil and its main constituents were evaluated in vitro. Results: We identified the major compounds as camphor, borneol, and 1,8-cineole. The oil possesses anti-inflammatory activity inhibiting NO production. It also inhibits intracellular DCFH oxidation induced by tert-butylhydroperoxide. Anti-inflammatory activity of essential oil appears driven mainly by α-humulene while antioxidant activity is provided by α-pinene and caryophyllene oxide. Essential oil from T vulgare was active against both Escherichia coli and Staphylococcus aureus with camphor and caryophyllene oxide responsible for antibacterial activity. Finally, T. vulgare essential oil was slightly cytotoxic against the human healthy cell line WS1 while α-humulene and caryophyllene oxide were moderately cytotoxic against A-549, DLD-1, and WS1. Conclusion: We report, for the first time, links between the specific compounds found in T. vulgare essential oil and anti-inflammatory, antioxidant, antibacterial, and cytotoxic activities. T. vulgare essential oil possesses interesting biological properties.