Eucalyptus-derived essential oils alleviate microbes and modulate inflammation by suppressing superoxide and elastase...

Area of Science:

• Phytochemistry
• Pharmacology
• Medicinal Chemistry

Background:

• Eucalyptus species are globally cultivated for their pharmaceutical and industrial applications.
• Understanding the chemical variability and bioactivity of different Eucalyptus species is crucial for their effective utilization.

Purpose of the Study:

• To conduct a comparative analysis of the chemical composition of essential oils from three Egyptian Eucalyptus species: *E. citriodora*, *E. camaldulensis*, and *E. ficifolia*.
• To evaluate the *in vitro* anti-inflammatory, antiviral (including anti-SARS-CoV-2), antibacterial, and antifungal activities of these essential oils.
• To perform *in silico* studies to confirm biological activities and predict ADME parameters of identified compounds.

Main Methods:

• Hydrodistillation was used to obtain essential oils from the three Eucalyptus species.
• Gas Chromatography-Mass Spectrometry (GC-MS) was employed for chemical composition analysis.
• *In vitro* assays were conducted to assess anti-inflammatory, antiviral, antibacterial, and antifungal activities. *In silico* analysis was performed on macromolecular drug targets.

Main Results:

• *E. citriodora* oil was rich in citronellal (54.9%) and citronellol (25.4%), showing the highest inhibitory activity on superoxide radical and elastase release.
• *E. camaldulensis* oil major constituents were β-cymene (12.7%) and 1,8-cineole (11.7%).
• *E. ficifolia* oil contained *trans*-β-ocimene (22.4%) and 1,8-cineole (13.5%), exhibiting significant antiviral activity against Hepatitis A, Herpes Simplex, and Coxsackie viruses, and potent antibacterial activity against *Staphylococcus aureus* (MIC ≈ 25 μg/mL). *E. camaldulensis* oil was most active against *Candida albicans* (MIC ≈ 45 μg/mL).

Conclusions:

• The chemical profiles of the essential oils vary significantly among the studied Eucalyptus species.
• *E. ficifolia* essential oil demonstrates promising broad-spectrum antiviral and antibacterial potential.
• The findings support the ethnobotanical use of Eucalyptus oils and highlight *E. ficifolia* as a valuable source for pharmaceutical development.