Essential oils composition, antibacterial and antioxidant activities of hydrodistillated extract of Eucalyptus globulus fruits

Abstract

Aromatic plants and their essential oils have been used since antiquity in flavor and fragrances, as condiments or spices, in medicines, as antimicrobial/insecticidal agents, and to protect stored products. The present study was undertaken: to determine (:) the chemical composition of essential oils extract from Eucalyptus globulus (E. globulus) fruits, using Gas-Chromatography coupled with Mass Spectrometry (GC/MS) method, to examine their antioxidant activity (DPPH’, reducing power and lipid peroxidation inhibition assays) compared to that of Butylated hydroxyanisole (BHA) standard, and to estimate their antibacterial effects against reference pathogenic strains: Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Listeria innocua (L. innocua), Escherichia coli (E. coli), Pseudomonas aerugenosa (P. aerugenosa), compared to that of two antibiotics (tetracycline and gentamicin). Twenty eight volatile compounds were identified, with the predominance of sesquiterpenes and oxygenated sesquiterpenes compounds (61.2%). The results of the antioxidant activities (DPPH scavenging activity, reducing power and inhibition of lipid peroxidation activity) of essential oils extract revealed weak activities with IC50 values of 27.0 ± 0.2 mg mL−1, 32.9 ± 1.8 mg mL−1 and 4.9 ± 0.2 mg mL−1, respectively; as compared to those of Butylated hydroxyanisole (BHA) standard that were about 0.05 ± 0.0 mg mL−1, 0.03 ± 0.0 mg mL−1 and 0.5± 0.2 mg mL−1, respectively. The antibacterial activity shows an inhibition effect of essential oils extracts against all the tested bacteria with MIC of 3 and 4 mg mL−1. A bactericidal effect is observed, with MBC varying between 3.6 and 9.0 mg mL−1, which demonstrates the sensibility of all tested bacteria to the essential oils of E. globulus fruits.