Bactericidal and antioxidant effects of essential oils from Satureja montana L., Myristica fragrans H. and Cymbopogon flexuosus.

The extraction and characterization of the essential oils (EO) from Satureja montana L., Myristica fragrans H. and Cymbopogon flexuosus and the determination of their antibacterial and antioxidant activities were achieved. The EO were identified by gas chromatography/mass spectrometry and quantified by gas chromatography using a flame ionization detector. The antibacterial potential against Escherichia coli and Staphylococcus aureus was evaluated by cell susceptibility assays and by scanning electron microscopy. The antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl assay, by ß-carotene bleaching and by determining the reducing power. Borneol (36·18%), γ-terpineol (12·66%) and carvacrol (11·07%) were the principal components in the EO from S. montana, and sabinene (49·23%) and α-pinene (13·81%) were found in the EO from M. fragrans. Geranial (59·66%) and neral (38·98%) isomers were the only major components in the EO from C. flexuosus. The EO from S. montana was effective against E. coli, with minimum inhibitory and bactericidal concentrations (MIC and MBC) of 6·25 µl ml-1 , whereas bactericidal potential against both was observed for the EO from M. fragrans; MIC = 6·25 µl ml-1 for S. aureus and MBC = 12·5 µl ml-1 for E. coli. A significant protective role on lipid substrates in the ß-carotene bleaching assay was seen for the EO from S. montana and M. fragrans. Overall, such EO can be promising agents against pathogenic bacteria and for protecting biomolecules during oxidative stress.

Antifungal activity of poly(ε-caprolactone) nanoparticles incorporated with Eucalyptus essential oils against Hemileia vastatrix.

Coffee (Coffea L.) is one of the main crops produced globally. Its contamination by the fungus Hemileia vastatrix Berkeley and Broome has been economically detrimental for producers. The objective of this work was to extract and characterize the essential oils from Eucalyptus citriodora Hook, Eucalyptus camaldulensis Dehn and Eucalyptus grandis Hill ex Maiden, produce and characterize nanoparticles containing these essential oils and evaluate the in vivo and in vitro antifungal activity of free and nanoencapsulated essential oils. The principal constituent of the essential oil from E. citriodora was citronellal; that from E. grandis was α-pinene; and that from E. camaldulensis was 1,8-cineol. The in vitro antifungal activity against the fungus H. vastatrix was 100% at a concentration of 1000 µl l-1 for all the oils and nanoparticles containing these natural products. The sizes of the nanoparticles produced with the essential oils from E. citriodora, E. camaldulensis and E. grandis were 402·13 nm, 275·33 nm and 328·5 nm, respectively, with surface charges of -11·8 mV, -9·24 mV and - 6·76 mV, respectively. Fourier transform infrared analyses proved that the encapsulation of essential oils occurred in the polymeric matrix of poly(ε-caprolactone). The incorporation of essential oils into biodegradable poly(ε-caprolactone) nanoparticles increased their efficiency as biofungicides in the fight against coffee rust, decreasing the severity of the disease by up to 90·75% after treatment with the nanoparticles containing the essential oil from E. grandis.