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Pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease, a serious threat to global forest populations of conifers, especially Pinus spp. A time-course study of the essential oils (EOs) of 2-year-old Pinus halepensis, Pinus pinaster, Pinus pinea and Pinus sylvestris following inoculation with the PWN was performed. The constitutive and nematode inoculation induced EOs components were analyzed at both the wounding or inoculation areas and at the whole plant level. The enantiomeric ratio of optically active main EOs components was also evaluated. External symptoms of infection were observed only in P. pinaster and P. sylvestris 21 and 15 days after inoculation, respectively. The EO composition analysis of uninoculated and unwounded plants revealed the occurrence of chemotypes for P. pinaster, P. halepensis and P. sylvestris, whereas P. pinea showed a homogenous EO composition. When whole plants were evaluated for EO and monoterpene hydrocarbon enantiomeric chemical composition, no relevant qualitative and quantitative differences were found. Instead, EO analysis of inoculated and uninoculated wounded areas revealed an increase of sesquiterpenes and diterpenic compounds, especially in P. pinea and P. halepensis, comparatively to healthy whole plants EOs., (© 2017 Wiley-VHCA AG, Zurich, Switzerland.)

Volatile-oils chemical composition and bioactivity of the essentail oils from Plectranthus barbatus, P. neochilus, and P. ornatus (Lamiaceae) were assessed. Aerial parts from these three related Plectranthus species were collected from cultivated plants grown in Portugal, during vegetative and flowering phases. Volatiles, isolated by distillation-extraction, were analyzed by GC and GC/MS. Monoterpene hydrocarbons (12-74%) and sesquiterpene hydrocarbons (4-45%) constituted the main fractions in all volatiles. α-Pinene (3; 12-67%), oct-1-en-3-ol (6; traces-28%), β-pinene (7; 0.1-22%), and β-caryophyllene (50; 7-12%) dominated P. barbatus volatiles. P. neochilus major volatile components were α-terpenyl acetate (41; traces-48%), α-thujone (2; 2-28%), β-caryophyllene (50; 2-28%), β-pinene (7; 1-25%), and α-pinene (3; 1-19%). Oct-1-en-3-ol (6; 13-31%), β-pinene (7; 11-24%), α-pinene (3; 11-19%), and β-caryophyllene (50; traces-11%) were the main constituents from P. ornatus volatiles. These chemical compositions were rather different from those previously found for specimens harvested in Africa and Brazil. Moreover, the volatiles from the flowers are herewith reported for the first time. Essential oils, isolated by hydrodistillation from leaves and stems, showed a yellowish color and unpleasant odor, with yields ranging from 0.08% to 0.84% (v/dry weight). Antioxidant and antimicrobial activities of the essential oils were evaluated by DPPH· and TBARS assays, and agar disc-diffusion method, respectively. Results showed low or moderate antioxidant capacity and significant antimicrobial activity against Gram-positive bacteria., (Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.)