Chemical composition and antimicrobial activity of Eucalyptus radiata leaf essential oil, sampled over a year.

This study investigated the seasonal variation of the chemical composition and antimicrobial activity ofEucalyptus radiataleaf essential oil. Young and matureEucalyptus radiataleaf material was collected monthly (January 2014 to December 2014), hydrodistilled and analyzed using GC-MS. Essential oil yields ranged from 0.14% to 4.31% (w/w). The major compounds were 1,8-cineole (65.7% ± 9.5), α-terpineol (12.8% ± 4.4) and limonene (6.5% ± 2.4). Chemometric tools were used to determine seasonal variations, which showed slight variance inE. radiatachemistry between seasons. The minimum inhibitory concentration (MIC) assay showed that the highest activity was noted against the Streptococci (0.19–2.00 mg/mL) andLactobacillus acidophilus(0.19–1.75 mg/mL). The activity of theE. radiataleaf essential oil is dependent on the unique ratio of its compounds. TheE. radiataleaf essential oil showed good oil yields, a relatively consistent chemical profile and noteworthy antimicrobial activity that rivals other commercial Eucalypt counterparts. [ABSTRACT FROM AUTHOR]