Chemical Composition and Antifungal Activity of Essential Oils from Flowers, Leaves and Peels of Tunisian Citrus aurantium Against Penicillium digitatum and Penicillium italicum

Abstract

The essential oils isolated by hydro-distillation from the peel, leaves and flowers of Citrus aurantium var amara were analyzed by GC-MS and GC-FID. The major components were limonene (87.02%), linalyl acetate (53.76%) and linalool (39.74%), respectively identified from peels, leaves and flowers essential oils. The antifungal activity of the oils and its components (α- terpineol, terpinen-4-ol, linalool and limonene) was tested by poisoned food technique and agar well diffusion assay against two plant pathogenic fungi Penicillium digitatumand Penicillium italicum isolated from different sites of Tunisia. The oil that showed better activity was neroli oil (the inhibition zone diameter reached 32 ± 2 mm and the inhibition percentage was morethan 50% for P. italicum isolated from Soliman) followed by leaves essential oils (P. italicum isolated from Soliman the inhibition zone diameter was 22.6 ± 1.1 mm and the inhibition percentage was 60.7 ± 2.8%), while peels essential oils were inactive against all tested isolates. Fungal sporulation has been reduced to 22.5% and 25% respectively for P. italicum and P. digitatum at 50 mg/mL of neroli oil. In addition, weight of mycelia were also decreased almost 40 times after adding 50 mg/mL of neroli oil for both P. italicum and P. digitatum. In vivo experiments have confirmed that neroli oil was able to show the highest antifungal activity by reducing incidence of infection up to 36% after storage. Furthermore, isolates, identified as resistant to the fungicide, were found to be sensitive to the action of the oils.