Phytochemical Profile and <i>In Vitro</i>Antioxidant Properties of Essential Oils from Powder Fractions of <i>Eucalyptus camaldulensis</i>Leaves

Dried leaves of Eucalyptus camaldulensis were finely grinded and fractionated by sieving into four granulometric classes (<100 μm, 100 - 200 μm, 200 - 355 μm and >355 μm). The obtained powder fractions were used for essential oil (EO) extraction by hydrodistillation and their phytochemical profile and in vitro antioxidant activities were evaluated. The mother powder (unsieved powder) was used for comparison. Particle size exerted a significant influence (p < 0.05) on the phytochemical composition and in vitro antioxidant properties of the EOs. Comparatively, the mother powder had the highest contents of α-pinene (55.6%), camphene (3.4%) and limonene (3.7%), while 1,8-cineole (26.6% and 22.4%), exo-fenchol (5.6% and 3.5%), α-campholenol (4.2% and 3.4%), L-trans-pinocarveol (5.5% and 2.7%), L-borneol (12.6% and 6.8%) and α-terpineol (16.4% and 7.6%) are the main compounds of EOs from the <100 μm and 100 - 200 μm fractions, respectively. The antioxidant activities of the EOs revealed higher radical-scavenging activities DPPH (90.62% and 70.46%) and ABTS (89.59% and 73.31%) for finer fractions (<100 μm and 100 - 200 μm, respectively). The best reducing power (36.15% and 34.27%) were also found in these finer powder fractions which improved by more than 2 times the value of mother powder (reducing power of 17.01%). These results suggest that grinding followed by sieve fractionation concentrates the majority of antioxidant phytochemicals in the EOs of the finer powder fractions of E. camaldulensis leaves. Finer powders could be used as functional ingredients in food formulations for the management of chronic diseases.