| 1. |
- Eriksson, Carina, et al.
(författare)
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Antifeedants and feeding stimulants in bark extracts of ten woody non-host species of the pine weevil, Hylobius abietis
- 2008
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 34:10, s. 1290-1297
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Tidskriftsartikel (refereegranskat)abstract
- Bark of ten woody species, known to be rejected as a food source by the pine weevil, Hylobius abietis, were sequentially extracted by a Soxhlet apparatus with pentane followed by methanol. Species were alder (Alnus glutinosa), aspen (Populus tremula), beech (Fagus sylvatica), guelder rose (Viburnum opulus), holly (Ilex aquifolium), horse chestnut (Aesculus hippocastanum), lilac (Syringa vulgaris), spindle tree (Evonymus europaeus), walnut (Juglans regia), and yew (Taxus baccata). Bark of each species was collected in southern Scandinavia during the summer. Resulting extracts were tested for antifeedant activity against the pine weevil by a micro-feeding choice assay. At a dose corresponding to that in the bark, methanol extracts from Aesculus, Taxus, Ilex, and Populus were antifeedant active, while pentane extracts of Aesculus, Fagus, Syringa, and Viburnum were stimulatory. Four known antifeedants against H. abietis, the straight-chained carboxylic acids, hexanoic and nonanoic acid (C6 and C9), carvone, and carvacrol were identified by gas chromatography (GC)-mass spectrometry (MS) in several extracts. The major constituents were identified and tested for feeding deterrence. The aromatic compounds benzyl alcohol and 2-phenylethanol are new non-host plant-derived feeding deterrents for the pine weevil. Additionally, two feeding stimulants, beta-sitosterol and 5-(hydroxymethyl)-2-furaldehyde, were identified. One active methanol extract of Aesculus bark was sequentially fractionated by liquid chromatography, and major compounds were tentatively identified as branched alcohols and esters of hexanoic acid. Five commercially available hexanoate esters and two commercially available branched alcohols were identified as new active antifeedants. Both stimulatory and inhibiting compounds were found in the same extracts and co-eluted in the same or adjacent fractions. The mix of semiochemicals of opposite activity in each extract or fraction could explain the stimulatory-, inhibitory-, or sometimes neutral activity. Generally, such co-occurrence confounds the isolation of antifeedants.
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| 2. |
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| 3. |
- Faldt, J., et al.
(författare)
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Correlations between selected monoterpene hydrocarbons in the xylem of six Pinus (pinaceae) species
- 2001
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Ingår i: Chemoecology. - 0937-7409 .- 1423-0445. ; 11:2, s. 97-106
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Tidskriftsartikel (refereegranskat)abstract
- The compositions of 23 monoterpene hydrocarbons of six pine species (Pinus sylvestris, P. yunnanensis ll,ris, P. armandii, P. tropicalis, P. cubensis and P. caribaca) were compared, using multivariate data analysis. Four of the six species were clearly different from the other species in a Principal Components Analysis (PCA) model, based on the relative amounts (selective normalization) of the monoterpenes. The correlation coefficients between constituents were determined separately for each species and the strongest correlations were found between (+)-alpha -pinene and (+)-camphene and between the corresponding (-)-enantiomers, in all species. This pattern, i.e. a good correlation in all species, was neither shown by the correlation of the structurally more similar (+)-alpha/beta -pinenes, nor by the (-)-alpha/beta -pinenes or within the enantiomeric pairs of alpha -pinene and beta -pinene. For these pairs of monoterpenes, good correlations were found in some species. None of the species showed good correlations in all the investigated monoterpene pairs presented here. Correlations between monoterpenes in insect-attacked trees (P. cubensis and P. caribaea, attacked by Dioryctria horneana, and P. yunnanensis, attacked by Tomicus piniperda) were also determined. The results are discussed from chemotaxonomic and biosynthetic points of view.
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| 4. |
- Isaksson, Dan, et al.
(författare)
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Enantiomerically enriched cryptone by lipase catalysed kinetic resolution
- 2006
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Ingår i: Tetrahedron. - : Elsevier BV. - 0957-4166 .- 1362-511X. ; 17:2, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Thiophenol was added to racemic cryptone (4-isopropyl-2-cyclohexene-1-one) and the resulting 1,4-addition products, cis- and trans-4-isopropyl-3-(phenylsulfanyl)cyclohexanone) were separated and the latter reduced to rac-1,3-cis-1,4-trans-4-isopropyl-3-(phenylsulfanyl)cyclo¬he¬xanol which was subjected to lipase catalysed resolution by acylation catalysed by CAL-B (Candida antarctica lipase B). The remaining alcohol was separated from the produced acetate, which was hydrolysed to the alcohol. The enantiomeric alcohols so obtained were oxidised. The initial products, probably sulfoxidoketones spontaneously decomposed to furnish enantiomerically enriched (R)- and (S)-cryptone with up to 76% and 98% ee, respectively.
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| 5. |
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| 6. |
- Månsson, Per, et al.
(författare)
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Antifeedants against Hylobius abietis pine weevils : An active compound in extract of bark of Tilia cordata linden
- 2005
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 31:5, s. 989-1001
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Tidskriftsartikel (refereegranskat)abstract
- Linden (Tilia cordata) bark contains antifeedants effective against the large pine weevil, Hylobius abietis. Soxhlet extraction of inner and outer bark resulted in an extract which showed antifeedant activity in a micro-feeding assay. The extract was fractionated by chromatography on silica gel using gradient elution with solvents of increasing polarity. The content of the fractions obtained was monitored by thin layer- and gas chromatography. Fractions of similar chemical composition were merged. Two of the 17 fractions showed antifeedant activity in the micro feeding assay. Nonanoic acid was identified in both of these fractions. Subsequent testing in the micro feeding assay showed that nonanoic acid possessed strong antifeedant activity against H. abietis adults.
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| 7. |
- Sjödin, Kristina, et al.
(författare)
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Occurrence and correlations of monoterpene hydrocarbon enantiomers in Pinus sylvestris and Picea abies
- 2000
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Ingår i: Journal of Chemical Ecology. - 0098-0331 .- 1573-1561. ; 26:7, s. 1701-1720
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Tidskriftsartikel (refereegranskat)abstract
- The relative amounts and enantiomeric compositions of monoterpene hydrocarbons in branch and trunk xylem, in needles, and in resin from apical buds in 18 Pinus sylvestris trees have been determined and compared with the terpene content in branch xylem and needles of Picea abies. Besides the high amount of (+)-3-carene, an excess of (+)-alpha-pinene has been found in P. sylvestris, whereas in P. abies (-)-alpha-pinene dominates over (+)-alpha-pinene. In P. sylvestris, clear positive correlations were found between (+)-alpha-pinene and (+)-camphene in the four tissues analyzed. Good positive correlations were also observed between (-)-alpha-pinene and (-)-camphene in the two types of xylem, between (+)-alpha-pinene and (+)-beta-pinene in the resin, and between tricyclene and (-)-camphene in resin and needles. In P. abies, positive correlations were found between (+)-alpha-pinene and (+)-camphene in the branch xylem and between tricyclene and (-)-camphene as well as between (-)-alpha-pinene and (-)-camphene in the needles. Complex relationships between (-)-alpha-pinene and (-)-beta-pinene were found both in the P. abies and in the P. sylvestris tissues. The importance of the enantiomeric composition of alpha-pinene for the host selection of Ips typographus, Tomicus piniperda, and Hylobius abietis is discussed.
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