Essential oils obtained by hydrodistillation from the different parts (stems, adult leaves, immature flowers and fruits) of Eucalyptus oleosa were screened for their antioxidant and antimicrobial properties and their chemical composition. According to GC-FID and GC-MS, the principal compound of the stem, immature flowers and the fruit oils was 1,8-cineole, representing 31.5%, 47.0% and 29.1%, respectively. Spathulenol (16.1%) and γ-eudesmol (15.0%) were the two principal compounds of adult leaves oil. In the DPPH (1,1-diphenyl-2-picrylhydrazyl) assay, the oils of the four parts showed moderate antioxidant activity. In the ABTS (2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate) assay, the most active part was the adult leaves, with a IC 50 value 13.0 ± 0.6 mg/L, followed by stems (IC 50 = 43.5 ± 1.4 mg/L). The essential oils showed a better antibacterial activity against Gram-positive and Gram-negative bacteria, and a significant antifungal

Essential oils of four different Eucalyptus species (Eucalyptus salubris, Eucalyptus salmonophloia, Eucalyptus oleosa, and Eucalyptus gracilis) grown in southern Tunisia were screened for their antioxidant and antimicrobial properties as well as their chemical compositions. According to gas chromatography-flame ionization detection and gas chromatography-mass spectrometry analysis, chemical compositions of the Eucalyptus species E. salubris (27 compounds; 99.2%), E. salmonophloia (31 compounds; 99.2%), E. oleosa (32 compounds; 97.6%), and E. gracilis (18 compounds; 97.7%) were identified. In the 1,1-diphenyl-2-picrylhydrazyl assay, the antioxidant activity was in the range of 12.0-52.8 mg/mL, whereas in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate assay, E. oleosa (176.5 +/- 3.1 mg/L) gave the best inhibition result. To evaluate antimicrobial activity, all essential oils were tested against bacteria (two Gram-positive and two Gram-negative), two yeast, and two fungi. Essential oils exhibited an interesting antibacterial activity against all microorganisms tested (activity was better against Gram-positive bacteria) except for Staphylococcus aureus and Escherichia coli. Correlations between chemical composition and biological and antioxidant activities were studied.

This study investigated the chemical composition (by using gas chromatography/flame ionization detection and gas chromatography/mass spectrometry, an antioxidant [1,1-diphenyl-2-picrylhydrazyl] [DPPH] radical-scavenging assay, and a 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate [ABTS] radical cation-scavenging assay) and the antimalarial and cytotoxic activities of essential oil extracted from leaves of Melaleuca armillaris. Thirty-two components representing more than 98% of the total composition of the essential oil were identified. The main components were 1,8-cineole (85.8%), camphene (5.05%), and α-pinene (1.95%). The antioxidant activity by ABTS assay showed a mean (± standard deviation) 50% inhibitory concentration (IC(50)) value of 247.3 ± 3.9 mg/L, and the DPPH assay yielded an IC(50) value of 2183.6 ± 44.3 mg/L. The antimalarial study indicated that the essential oil had mild activity against the chloroquine-resistant Plasmodium falciparum FcB1 strain (IC(50), 27 ± 2 mg/L). The cytotoxic activity of this essential oil was tested against MCF7 human breast cancer cells and was found to be high (IC(50), 12 ± 1 mg/L).