Bioactivity and Nanoformulation of Eucalyptus camaldulensis Essential Oils: Implications for Antioxidant and Anti-inflammatory Applications

Abstract

This study explored the antioxidant and anti-inflammatory potential of Eucalyptus camaldulensis essential oils by developing nanoemulsions from leaf and fruit oils using low-energy emulsification. The resulting stable nanoemulsions exhibited particle sizes of 215.3 and 250.3 nm for fruit and leaf oil-based nanoemulsions, with polydispersity indices of 0.228 and 0.367 and zeta potentials of −84.1 and −30.4 mV, respectively. The transmission electron microscopy confirmed the formation of spherical, well-dispersed nanoparticles. Gas chromatography-mass spectrometry analysis revealed the dominance of limonene (14.52%), spathulenol (14.3%), and bicyclogermacrene (12.39%) in fruit oil, while spathulenol (21.34%), p-cymene (17.95%), and cryptone (11.03%) were the major constituents in leaf oil. Sesquiterpenes, especially spathulenol, increased dramatically due to nanoemulsification, with 49.15% and 25.08% in fruit and leaf oil-based nanoemulsions. Leaf and fruit oils showed higher antioxidant activity than oil-based nanoemulsions using DPPH and ABTS assays. In vivo analysis revealed a time-dependent decrease in edema volume, with nanoemulsion groups showing the most significant effects, indicating that E. camaldulensis oil-based nanoemulsions maintain anti-inflammatory properties over time. They also improved growth and metabolic efficiency while reducing organ damage and nephrotoxicity in rats exposed to CCl4 toxicity. Compared to crude oils, superior hepatoprotective effects were noted in oil-based nanoemulsions, alleviating oxidative stress and inflammation. Docking studies indicated that major constituents interacted with proteins involved in oxidative stress and inflammation, with sesquiterpenes showing the highest binding affinities, while certain monoterpenes also demonstrated significant docking scores against oxidative stress enzymes. The study highlights the potential antioxidant and tissue-protective properties of Eucalyptus camaldulensis essential oils and their nanoemulsions.