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Citrus essential oils are used in food to confer flavor and aromas. The citrus essential oils have been granted as GRAS and could be used as antimicrobial additives to control bacterial quorum sensing from potential food bacterial pathogens. The chemical composition and inhibitory activity of Citrus paradisi (grapefruit) essential oils obtained by cold-pressed method (EOP) and cold-pressed method followed by steam distillation, against Pseudomonas aeruginosa were determined. The GC-MS analyses of the oil indicated the amount of the essential oil components was highest with D-limonene in both cases. However, the extraction method modified the chemical composition. EOP had higher amount of coumarins and flavonoid as well as less oxygenated terpenoids. At 0.1 mg/mL essential oils were not able to modify the bacterial development but inhibited the P. aeruginosa biofilm production between 52% and 55%, sessile viability between 45% and 48%, autoinducer production and elastase activity between 30% and 56%. Limonene was less effective at inhibiting P. aeruginosa than the essential oils, suggesting a synergistic effect of the minor components. According to our results, grapefruit essential oils could be used as a food preservative to control P. aeruginosa virulence. [ABSTRACT FROM AUTHOR]

Chemical composition of commercialOriganum compactumandCinnamomum zeylanicumessential oils and the antifungal activity against pathogenic fungi isolated from Mediterranean rice grains have been investigated. Sixty-one compounds accounting for more than 99.5% of the total essential oil were identified by using gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). Carvacrol (43.26%), thymol (21.64%) and their biogenetic precursorsp-cymene (13.95%) and γ-terpinene (11.28%) were the main compounds in oregano essential oil, while the phenylpropanoids, eugenol (62.75%), eugenol acetate (16.36%) and (E)-cinnamyl acetate (6.65%) were found in cinnamon essential oil. Both essential oils at 300 μg/mL showed antifungal activity against all tested strains.O. compactumessential oil showed the best antifungal activity towardsFusariumspecies andBipolaris oryzaewith a total inhibition of the mycelial growth. In inoculated rice grains at lower doses (100 and 200 μg/mL) significantly reduced the fungal infection, soO. compactumessential oil could be used as ecofriendly preservative for field and stored Valencia rice. [ABSTRACT FROM PUBLISHER]

The leaves of Cinnamomum tamala L. (Lauraceae) were collected from seven plants occurring in seven different areas of Manipur and analyzed for their essential oil and eugenol contents using GC and GC/MS. The yield of the oil was found to vary from 1.5-5.6% (w/w), on a thy weight basis. A total of 79 compounds were identified in the oils. Eugenol was found as a major compound in the leaf oils and its concentration varied from 35.1-94.3% followed by α-phellandrene (1.0-25.4%). [ABSTRACT FROM AUTHOR]

Rind oils of nine cultivars of mandarin originated by recent mutation (Loretina, Marisol, Arrufatina, Clemenules, Clemenpons, Hernandina, Oronules, Satsuma Okitsu, Satsuma Owari) belonging to the Citrus reticulata Blanco species and 2 hybrids Fortune (Citrus tangerine Hort. ex Tan x Citrus clementina Hort ex Tan) and Nova (Tangelo Orlando x Citrus clementina Hort ex Tan) were obtained from ripe fruits of trees growing in the same environmental and cultivated conditions. The study of their chemical composition was carried out by capillary GC, GC/MS and the results were submitted to discriminant analysis. The first discriminant function separates the α-thujene chemocultivar, corresponding to oriental mandarin cultivars (Satsuma Okitsu, Satsuma Owari), from the Mediterranean cultivars. Inside this last group, the second discriminant function split up the sabinene chemocultivar (Marisol, Arrufatina Clemenpons and Loretina from the hybrids group (Fortuna and Nova) and alters (Clemenules and Hernandina)). The differential compounds of these groups are: α-thujene α-pinene, sabinene, myrcene, limonene, linalool, α-terpineol and germacrene-D. [Copyright &y& Elsevier]

The essential oil composition of Cistus ladanifer grown in central Spain was analysed by gas chromatography and gas chromatography/mass spectrometry, revealing it to be rich in oxygenated compounds, with trans-pinocarveol (20.00%), bornyl acetate (7.03%) and terpinen-4-ol (6.37%) as the main monoterpene compounds. Viridiflorol (13.59%) and ledol (4.36%) were the main constituents of the oxygenated sesquiterpene fraction. Large amounts of α-pinene (4.70%) were found in the hydrocarbonated fractions. To study its possible use as a natural herbicide, the oil was tested in vitro against Amaranthus hybridus, Portulaca oleracea, Chenopodium album, Conyza canadensis and Parietaria judaica, completely inhibiting A. hybridus germination, and nearly blocking C. canadensis and P. judaica germination at all concentrations assayed. In P. oleracea, the oil showed less effect, inhibiting its germination at the higher doses studied. It did not control C. album germination. Regarding seedling length, the oil had strong phytotoxic activity, being effective at all concentrations tested.