Comparison of the Composition and Antimicrobial Activities of the Essential Oils of Green Branches and Leaves of Egyptian Navel Orange (Citrus sinensis (L.) Osbeck var. malesy)

Abstract

The essential oils isolated from the leaves and green branches of the Egyptian navel orange trees were analyzed by GC and GC/MS. A total of 33 and 24 compounds were identified from the oils of the leaves and branches accounting for 96.0% and 97.9%, respectively, of the total detected constituents. The major ones were sabinene (36.5; 33.0%), terpinen-4-ol (8.2; 6.2%), δ-3-carene (7.0; 9.4%), limonene (6.8; 18.7%), trans-ocimene (6.7; 6.1%), and β-myrcene (4.5; 4.4%). The antimicrobial activities of both oils were evaluated using the agar-well diffusion method toward three representatives for each of Gram-positive bacteria, Gram-negative bacteria, and fungi. The oil of leaves was more effective as antimicrobial agent than that of the branches. Streptococcus pyogenes, Staphylococcus aureus, Salmonella typhimurium, and Aspergillus fumigatus were the most sensitive bacteria and fungi by the leaves oil.

Keywords: Antimicrobial activities; Branches; Essential oils; Leaves; Navel orange.