Investigation of peel and leaf essential oils of Citrus clementina Hort. ex Tan. growing in the south of Vietnam

The essential oils from peels and leaves of Citrus clementine Hort. ex Tan. were extracted via two methods: conventional hydrodistillation (CHD) and microwave-assisted hydrodistillation (MAHD). Their physicochemical properties were investigated. Their chemical compositions of the oils were determined by GC/FID and GC/MS. A total of forty-one and seventy-seven compounds of the total essential oil composition of the peels and leaves respectively were identified. The peel oils were dominated by monoterpene hydrocarbons in which limonene was the main component (95.48% [CHD], and 95.03% [MAHD]). The leaf oils were also dominated by sesquiterpene hydrocarbons with sabinene (26.02% [CHD], and 19.52% [MAHD]), β-elemene (10.50% [CHD], and 18.04% [MAHD]), linalool (9.88% [CHD], and 7.51% [MAHD]), (E)-β-ocimene (5.87% [CHD], and 5.00% [MAHD]), β-caryophyllene (4.04% [CHD], and 7.49% [MAHD]), and δ-selinene (4.76% [CHD], and 8.02% [MAHD]) as major components. The oil contents of peels were obtained with 5.31% and 5.67% by CHD method and MAHD method, respectively. The oil contents of the leaves were obtained with 0.33% and 0.20% by CHD method and MAHD method, respectively. The antimicrobial activity (disc diffusion antibiotic sensitivity assay) of the oils was investigated against six reference test organisms including two Gram (+) bacteria (Bacillus subtilis, Staphylococcus aureus), three Gram (-) bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella flexneri), and one fungus (Candida albicans).