The Effect of Altitude on the Chemical Composition, Antioxidant and Antimicrobial Activities of Eucalyptus globulus Labill. Essential Oils

Abstract

Eucalyptus globulus Labill., a medicinal plant native to Eastern Morocco, is renowned for its therapeutic qualities and pleasant aroma. This study aimed to investigate the effect of altitude on the chemical composition, and biological activities of E. globulus leaves essential oil. E. globulus leaves were collected from three different locations; Nador, Morocco, Taourirt, Morocco, and Ain Benimathar, Morocco with altitudes 7 m, 380 m, and 950 m, respectively. The essential oils were extracted by hydro-distillation. The chemical composition of the oils was determined by GC-MS analysis. The antioxidant potential was assessed by total antioxidant capacity (TAC) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The antimicrobial activity was tested against various bacterial and fungal strains using standard procedures. GC-MS analysis revealed significant variations in the chemical composition of the essential oils. For the sample collected at 7 m altitude, 17 constituents were identified in the essential oil, with the major constituents being β-Cymene (17.21%), Eucalyptol (10.88%), α-pinene (10.54%), Phellandrene (9.70%), and p-Menth-1-en-4-ol (8.92%). The essential oil of the sample collected at 380 m altitude, contained mainly Eucalyptol (45.53%), 4,6-di-t-Butylpyrogallol (18.27%), α-pinene (7.25%), β-Cymene (6.24%), and Camphor (5.26%). While the essential oil of the sample collected at 950 m altitude were composed mainly of Eucalyptol (24.92%), Pinocarveol (16.94%), 4,6-Di-t-Butylpyrogallol (14.40%), β-Eudesmol (12.50%), and α-pinene (11.30%). The oils exhibited significant antioxidant and antimicrobial activities with greater activity against the fungi. This study has highlighted the impact of cultivation altitude on the chemical composition and the biological effect of E. globulus essential oil.