Chemical Composition and Biological Activities of Eucalyptus globulus Essential Oil

Efficacy of ground herb-based and essential oil-based phytobiotics on the intestinal health and performance of nursery pigs challenged with F18+Escherichia coli

This study aimed to evaluate the efficacy of using ground herb-based phytobiotics and essential oil-based phytobiotics in pig diets on intestinal health and growth performance (GP) of nursery pigs challenged with F18+Escherichia coli. Forty nursery pigs (6.4 ± 0.1 kg) at 21 d of age were individually housed and assigned to 4 dietary treatments in a randomized complete block design, with body weight and sex as blocking factors. Basal diets were fed to pigs for 28 d in 3 phases. Treatments were negative control (NC): basal diet, non-challenged; positive control (PC): basal diet, challenged with F18+E. coli; HP: PC + 1% ground herb-based phytobiotics (Salcochek Pro, Ayurvet Limited, Kaushambi, India); EP: PC + 1% essential oil-based phytobiotics (Liq-biotic, Ayurvet Limited). The GP was recorded for each phase and fecal score (FS) was measured daily. On day 7 postweaning, the challenged groups were orally inoculated with F18+E. coli (2.0 × 1010 CFU), the NC treatment received a sterile saline solution. On day 28, pigs were euthanized to collect jejunal samples to evaluate intestinal health and relative abundance (RA) of jejunal mucosa-associated microbiota. Data were analyzed using the MIXED procedure on SAS 9.4. The PC increased (P < 0.05) the RA of Prevotellaceae, Lachnospiraceae, and Ruminococcaceae when compared to NC. The HP reduced (P < 0.05) the RA of Veillonellaceae, Prevotellaceae, and Lachnospiraceae when compared to PC. The EP tended to reduce the RA of Streptococcaceae (P = 0.073) and Corynebacteriaceae (P = 0.074) when compared to PC. The PC increased (P < 0.05) occludin and tended to increase (P = 0.096) toll-like receptor-4 (TLR4) when compared to NC. The PC decreased (P < 0.05) average daily gain and average daily feed intake when compared to NC in days 7 to 28. The PC increased FS (P < 0.05) compared to the HP and EP days 7 to 11. The HP and EP decreased (P < 0.05) FS when compared to PC during days 7 to 11 and days 7 to 18. In conclusion, F18+E. coli challenge disrupted the jejunal mucosa-associated microbiota, increased TLR4 expression and FS, and consequently reduced GP. Both HP and EP phytobiotics supported intestinal morphology during the challenge to F18+E. coli by supporting enterocyte maturation. The HP and EP treatments exhibited antimicrobial-like effects by altering the jejunal mucosa-associated microbiota and reduced FS during the first 2 weeks post-challenge. The HP treatment showed potential antioxidant effects.

GC-MS Characterization and Bioactivity Study of Eucalyptus globulus Labill. (Myrtaceae) Essential Oils and Their Fractions: Antibacterial and Antioxidant Properties and Molecular Docking Modeling

BACKGROUND/OBJECTIVES

Eucalyptus globulus is a medicinal plant extensively used by the Moroccan population for treating a range of illnesses, especially respiratory conditions.

METHODS

This study aimed to assess the antioxidant and antibacterial properties of E. globulus essential oil and its individual fractions (F1, F2, and F3). Antioxidant activity was evaluated through iron-reducing power, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Antibacterial activity was tested using disk diffusion and dilution methods, supported by molecular docking studies. Furthermore, GC-MS analysis was conducted on the essential oil and its individual fractions.

RESULTS

GC-MS analysis identified the major compounds in the essential oil and its fractions as eucalyptol (62.32-42.60%), globulol (5.9-26.24%), o-cymene (6.89-24.35%), cryptone (7.10-15.95%), terpinen-4-ol (2.43-15.24%), and α-pinene (2.46-7.89%). Fraction F3 displayed the highest antioxidant activity in DPPH (IC50 = 3.329 ± 0.054 mg/mL) and ABTS assays (IC50 = 3.721 ± 0.027 mg/mL), while fraction F2 was most effective in the FRAP assay (IC50 = 1.054 ± 0.008 mg/mL). The essential oil and its fractions also showed antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Enterobacter cloacae, Escherichia coli, and Acinetobacter baumannii. Molecular docking further corroborated these findings, supporting both antioxidant and antibacterial activities.

CONCLUSIONS

The present findings demonstrate the antioxidant and antimicrobial properties of Eucalyptus globulus essential oil and its fractions, underscoring the need for further research to confirm their medicinal potential and explore pharmaceutical applications.

Bisphenol AF Caused Reproductive Toxicity in Rats and Cineole Co-Treatment Exhibited Protective Effect

Bisphenol AF (BPAF) is increasingly used and now found in products intended for human consumption. The protective effect of 1,8-cineole (CIN) against BPAF-induced reproductive toxicity was investigated. Four groups were created, with each group consisting of eight rats: control, BPAF (200 mg/kg), CIN (200 mg/kg), and BPAF + CIN groups. The results demonstrated that the BPAF group exhibited a decline in testosterone levels and a decrease in sperm parameters compared with the control. Additionally, higher levels of MDA were observed, along with lower levels of GSH and GPx activity. CAT activity also decreased slightly. Tnf-α, Nf-κB levels were significantly higher, and caspase-3 expression was elevated, while PCNA expression decreased. BPAF significantly increased tissue degeneration compared with the control. However, the BPAF + CIN group showed statistically significant improvements in sperm parameters, except for concentration. They also exhibited an increase in testosterone levels and an improvement in MDA and GSH levels compared with the BPAF group. However, GPx activity partially enhanced. Tnf-α and Nf-κB levels were significantly reduced, and caspase-3 levels declined while PCNA and Bcl-2 levels increased. The Johnsen Testicular Biopsy score showed a substantial increase. Overall, these results suggest that CIN co-treatment in rats enhanced reproductive health and exhibited antioxidant, antiapoptotic, and anti-inflammatory properties against BPAF-induced testicular damage.

Chemical profiling and spectroscopic studies of leaf volatile oil of Eucalyptus globulus from Botswana isolated by conventional hydrodistillation and ultrasound assisted hydrodistillation

Environmental factors have an influence on the chemistry and percentage recovery of volatile oils. Therefore, the chemical composition of Eucalyptus globulus (E. globulus) volatile oil from Botswana was determined. The volatile oil was isolated from the leaves of E. globulus plant by means of the conventional hydrodistillation and ultrasound assisted hydrodistillation at 50 W and 300 W. The extraction method that gave a better recovery of the volatile oil was ultrasound assisted hydrodistillation at 300 W with a yield of 2.50%. The volatile oil obtained by hydrodistillation and ultrasound assisted hydrodistillation at 50 W had comparable recovery yields of 2.24% and 2.20% respectively. Eucalyptol was identified as the major component in the oil. The amount of eucalyptol present in E. globulus volatile oil extracted by ultrasound assisted hydrodistillation (65%) show that the oil has a potential to be explored for therapeutic purposes.

Virucidal effects of eucalyptus essential oil on porcine reproductive and respiratory syndrome virus

Currently, the efficacy of vaccination for preventing and controlling PRRSV is insufficient. Therefore, there is an urgent need for novel effective preventive strategies. This study aimed to investigate the antiviral effect of Eucalyptus essential oil (EEO) against PRRSV in vitro. Marc-145 cells were infected with PRRSV (rJXA1-R), and the toxicity of EEO in the cells was measured using the Cell Counting Kit-8 method. Additionally, the antiviral effect of EEO on PRRSV-infected cells was assessed using three treatment methods: drug administration post-PRRSV inoculation (post-treatment), drug administration before PRRSV inoculation (pre-treatment), and simultaneous drug administration and PRRSV inoculation (co-treatment). The EEO could not inhibit virus adsorption and/or replication since post-treatment and pre-treatment did not prevent viral infectivity. However, EEO exerted a significant virucidal effect on PRRSV. When PRRSV-infected cells were treated with 0.0156, 0.0312, and 0.0625% EEO, the cell survival rates were 55.37, 118.96, and 121.67%, respectively, and the titer of progeny virions decreased from 5.77 Log10TCID50 to 5.21 Log10TCID50, 0.55 Log10TCID50, and less than 0.167 Log10TCID50, respectively (where TCID50 is the 50% tissue culture infected dose). The fluorescence intensity of the PRRSV N protein significantly decreased in the indirect immunofluorescence assay. When cells were co-treated with EEO (0.0625%) and PRRSV (1000 TCID50) for 15 min, the viral particles were inactivated, and PRRSV (1000 TCID50) particles loss infectivity when the co-treatment time reached 60 min. In a word, EEO has no obvious therapeutic effect on PRRSV infection, but it can effectively inactivate virus particles and make them lose the ability to infect cells. These findings provide insights for the development and use of EEO to treat PRRS.

Phytochemical characterization of forest leaves extracts and application to control apple postharvest diseases

The study investigated the antifungal and phytochemical properties of three forest plants (Eucalyptus globulus, Pistacia lentiscus, and Juniperus phoenicea) against apple diseases caused by Colletotrichum gloeosporioides and Alternaria alternata. The determination of the total polyphenol and flavonoid contents in the three aqueous extracts of studied plants showed that E. globulus exhibited the highest contents than those of P. lentiscus and J. phoenicea. Furthermore, the three studied extracts showed very appreciable antioxidant activity with decreasing order: E. globulus, P. lentiscus, and J. phoenicea. The phytochemical analysis showed different common phenolic acids in the three studied plants namely: quinic acid, gallic acid, chlorogenic acid, and caffeoylquinic acid as well as other flavonoids mainly quercetin and catechin. The results of the current study demonstrated that the fungistatic activity of E. globulus EO (4 and 2 µl/ml) seemed to be the most effective under laboratory conditions with an inhibition zone diameter above 16 mm. However, the poisoned food technique indicated that the aqueous extract (80%) and the essential oil (4 µl/ml) of E. globulus exhibited the highest mycelial growth (> 67%) and spore germination (> 99%) inhibition. Preventive treatments with essential oils (4 µl/ml) and aqueous extracts (80%) applied to apple fruits inoculated with A. alternata and C. gloeosporioides resulted in the lowest lesion diameter (< 6.80 mm) and disease severity index (< 15%) and the most favorable inhibitory growth (> 85.45%) and protective potentials (> 84.92%). The results suggest that E. globulus has a brilliant future in the management of anthracnose and Alternaria rot of apple and provide a basis for further studies on its effects under field conditions.

Disclosing the potential of Cupressus leylandii A.B. Jacks & Dallim, Eucalyptus globulus Labill., Aloysia citrodora Paláu, and Melissa officinalis L. hydrosols as eco-friendly antimicrobial agents

Antimicrobial resistance is a major global health concern, threatening the effective prevention and treatment of infections caused by microorganisms. These factors boosted the study of safe and green alternatives, with hydrosols, the by-products of essential oils extraction, emerging as promising natural antimicrobial agents. In this context, four hydrosols obtained from Cupressus leylandii A.B. Jacks & Dallim, Eucalyptus globulus Labill., Aloysia citrodora Paláu and Melissa officinalis L. were studied. Their chemical composition comprises neral, geranial, 1,8-cineole, terpinen-4-ol, and oplopanonyl acetate, compounds with recognised antimicrobial activity. Concerning antimicrobial activity, significant differences were found using different hydrosol concentrations (10-20% v/v) in comparison to a control (without hydrosol), showing the potential of the tested hydrosols to inhibit the microbial growth of Escherichia coli, Staphylococcus aureus, and Candida albicans. A. citrodora hydrosol was the most effective one, inhibiting 90% of E. coli growth and 80% of C. albicans growth, for both hydrosol concentrations (p < 0.0001). With hydrosol concentration increase, it was possible to observe an improved antimicrobial activity with significant reductions (p < 0.0001). The findings of this work indicate the viability of reusing and valuing the hydrosols, encouraging the development of green applications for different fields (e.g., food, agriculture, pharmaceuticals, and cosmetics).

The efficient activity of plant essential oils for inhibiting Botrytis cinerea and Penicillium expansum: Mechanistic insights into antifungal activity

Botrytis cinerea and Penicillium expansum produce deterioration in fruit quality, causing losses to the food industry. Thus, plant essential oils (EOs) have been proposed as a sustainable alternative for minimizing the application of synthetic fungicides due to their broad-spectrum antifungal properties. This study investigated the efficacy of five EOs in suppressing the growth of B. cinerea and P. expansum and their potential antifungal mechanisms. EOs of Mentha × piperita L., Origanum vulgare L., Thymus vulgaris L., Eucalyptus globules Labill., and Lavandula angustifolia Mill., were screened for both fungi. The results showed that the EO of T. vulgaris and O. vulgare were the most efficient in inhibiting the growth of B. cinerea and P. expansum. The concentration increase of all EO tested increased fungi growth inhibition. Exposure of fungi to EOs of T. vulgaris and O. vulgare increased the pH and the release of constituents absorbing 260 nm and soluble proteins, reflecting membrane permeability alterations. Fluorescence microscopic examination revealed that tested EOs produce structural alteration in cell wall component deposition, decreasing the hypha width. Moreover, propidium iodide and Calcein-AM stains evidenced the loss of membrane integrity and reduced cell viability of fungi treated with EOs. Fungi treated with EOs decreased the mitochondria activity and the respiratory process. Therefore, these EOs are effective antifungal agents against B. cinerea and P. expansum, which is attributed to changes in the cell wall structure, the breakdown of the cell membrane, and the alteration of the mitochondrial activity.

Essential Oils and Their Components Control Behaviour of Yellow Mealworm (Tenebrio molitor) Larvae

Beetle Tenebrio molitor L. (Coleoptera, Tenebrionidae) is a well-known pest of grain and flour in food stores and grocery shops. Recently, commercial cultivation of the insect was started for human food and animal feed. Behaviour control of this insect using natural repellents is promising both for grain protection and commercial cultivation. We analysed if natural products of plant origin, namely essential oils (EOs), could be used for this purpose. Behavioural tests were performed using EOs of six plants: thymus (Thymus vulgaris), eucalyptus (Eucalyptus globulus), spearmint (Mentha spicata), lavandin (Lavandula × hybrida), East-Indian lemongrass (Cymbopogon flexuosus), and clove (Eugenia caryophyllus). The most effective repellent for mealworm larvae was EO of spearmint, moderate activity showed that of clove and the least repellent were EOs of lemongrass thymus and lavandin. EO of eucalyptus caused almost no or very low effect. Six of the most abundant compounds of the EOs were selected for testing. The most effective single compounds were terpinene-4-ol and carvone, low-effective cis-sabinene hydrates and those of no significant activity were limonene, myrcene and γ-terpinene.

Essential Oil Composition, Antioxidant Activity and Leaf Micromorphology of Five Tunisian Eucalyptus Species

Eucalyptus species have been widely employed in the projects of reforestation in Tunisia. Although their ecological functions are controversial, these plants are indeed important to counteract soil erosion, and represent a fast-growing source of fuelwood and charcoal wood. In the present study, we considered five Eucalyptus species, namely Eucalyptus alba, E. eugenioides, E. fasciculosa, E. robusta, and E. stoatei cultivated in the Tunisian Arboreta. The aim was to carry out the micromorphological and anatomical characterization of the leaves, the extraction and phytochemical profile of the essential oils (EOs), and the evaluation of their biological properties. Four of the EOs showed the prevalence of eucalyptol (1,8-cineole) varying from 64.4 to 95.9%, whereas a-pinene predominated in E. alba EO (54.1%). These EOs showed in vitro antioxidant activity, and reduced the oxidative cellular stress as shown by their activity on reactive oxygen species (ROS) production, and modulation of the expression of antioxidant enzymes, such as glutamate-cysteine ligase (GCL) and heme oxygenase-1 (Hmox-1). Moreover, the EOs inhibited the production of nitric oxide (NO), showing anti-inflammatory activity. The data collected suggest that these EOs may be considered a promising therapeutic strategy for inflammation-based diseases and may represent an additional value for the economy of Tunisia.