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  • 1.
    Bohman, Björn
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Cavonius, Lillie
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unelius, C. Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds2009In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 11, no 11, p. 1900-1905Article in journal (Refereed)
    Abstract [en]

    Hydrolysis of labile esters of beta-hydroxyketones has been performed with whole plant tissue from various vegetables. The pheromone 5-hydroxy-4-methyl-3-heptanone (1) was used as the model compound. Hydrolysis of acetates and benzoates of 1 was unsuccessful using normal conditions of ester hydrolysis, both by chemical hydrolysis and by the means of commercial lipases. When, however, whole cells of carrot, celery root, eggplant, parsley root, parsnip and potato were used as reagents, hydrolysis of the acetates was successful. At low conversion the hydrolysis was stereoselective and at total conversion virtually no formation of by-products was observed. The selectivity varied among the eight vegetables that were evaluated. Methods of preparation and substrate-to-plant ratio were examined. Furthermore, acetates and benzoates of three analogous compounds [5-hydroxy-3-heptanone (2), 5-hydroxy-5-methyl-3-heptanone (3) and 5-ethyl-6-hydroxy-4-octanone (4)] were hydrolyzed by potato and sweet potato to various degrees, indicating that the method is general for the mild and stereoselective hydrolysis of secondary beta-alkoxy-and beta-aryloxyketones.

  • 2.
    Bohman, Björn
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. University of Western Australia, Australia.
    Flematti, Gavin R.
    University of Western Australia, Australia.
    Unelius, C. Rikard
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Practical one-pot stereospecific preparation of vicinal and 1,3-diols2017In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 58, no 1, p. 75-77Article in journal (Refereed)
    Abstract [en]

    A facile one-pot synthesis providing vicinal diols and 1,3-diols in >95% stereoisomeric purity from commercially available enantiopure hydroxy esters has been developed. The esters were reduced with DIBALH and alkylated in situ with 4-pentenylmagnesium bromide, which after workup generated the title diols as diastereomeric pairs. These pairs were easily separated by preparative chromatography, affording products with retained stereoisomeric purity from the starting materials. This method represents an expedient preparation of many common natural products, such as cerambycid beetle pheromones and intermediates towards bicyclic acetal bark beetle pheromones. (C) 2016 Elsevier Ltd. All rights reserved.

  • 3.
    Bohman, Björn
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Troger, A.
    University of Hamburg.
    Franke, S.
    University of Hamburg.
    Lorenzo, M. G.
    Fiocruz, Belo Horizonte, Brazil.
    Francke, W.
    University of Hamburg.
    Unelius, C. Rikard
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Structure Elucidation and Synthesis of Dioxolanes Emitted by Two Triatoma Species (Hemiptera Reduviidae)2011In: Journal of natural products (Print), ISSN 0163-3864, E-ISSN 1520-6025, Vol. 74, no 4, p. 690-694Article in journal (Refereed)
    Abstract [en]

    Volatiles from the metastemal glands of two species Of true bugs of the Triatominae subfamily, Triatoma brasiliensis and Triatoma infestans, Were analyzed by SPME-GC/MS. Two sets of new natural products were found: (4S,5S)- and (4R,SR)-2,2,4-triethyl-5-methyl-1,3-dioxolane (1) (major component) and (45*,5S*)-2,4-diethyl-2,S-dimethyl-1,3-dioxolane (2) (trace component),-,(2R/S,4S,SS)- as well as (2R/S,4R,5R)-4-ethyl-5-methyl-2-(1-methylethyl)-1,3-dioxolane (3) (minor component), (2R/S,4S*,5S*).-4-ethyl-5-methyl-2-(1-methylpropyl)-1,3-dioxolane (4), (trace component), and (2R/S,4S*,5S*)-4-ethyl-5-methyl-2-(2-methylpropyl)-1,3-dioxolane (5) (trace component). Syntheses of optically active 1 and 3 were carried out by reacting pure,enantiomers of 2,3-pentanediol with 3-pentanone or 2-methylpropanal. The preparation of, pure 1 stereoisomers of 2,3-pentanediol involved a novel key step for the synthesis of secondary alcohols: the reduction of a carboxylic ester by means of DIBAH and in situ alkylation of the intermediate by Grignard reaction at low temperature Starting from the pure enantiomers of methyl lactate; all four stereoisoniers of 2,3-pentanediol were synthesized. and transformed, to the corresponding isomers of 1 and 2. Relative configurations of the natural products and enantiomeric compositions of naturally occurring 1 and :2 were determined by comparison of their mass spectra and gas chromatographic retention times (co-injection) I with those of authentic reference samples.

  • 4.
    Bohman, Björn
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unelius, C. Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Synthesis of all four stereoisomers of 5-hydroxy-4-methyl-3-heptanone using plants and oyster mushrooms2009In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 65, no 42, p. 8697-8701Article in journal (Refereed)
    Abstract [en]

    All four possible stereoisomers of 5-hydroxy-4-methyl-3-heptanone were synthesized from common achiral reagents using fast, straightforward organic synthesis, including the use of whole tissue of Daucus carota, Solanum melongena, and Pleurotus ostreatus.

  • 5.
    Bohman, Björn
    et al.
    Univ Western Australia, Australia.
    Weinstein, Alyssa M.
    Australian Natl Univ, Australia.
    Unelius, C. Rikard
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Lorenzo, Marcelo G.
    Fiocruz MS, Brazil.
    Attraction of Rhodnius prolixus males to a synthetic female-pheromone blend2018In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 11, article id 418Article in journal (Refereed)
    Abstract [en]

    Background: The triatomine bug Rhodnius prolixus Stal, 1859 (Heteroptera: Reduviidae) is the primary vector of Chagas disease in Colombia and Venezuela. An important step in controlling Chagas disease is monitoring the growth and spread of bug populations to inform effective management. Such monitoring could be carried out using pheromone traps. To develop effective pheromone traps, it is vital to understand the pheromone chemistry of R. prolixus. Previous studies have found that female R. prolixus metasternal gland secretions induce males to: leave shelters, take off, orientate during walking, aggregate around mating pairs, and mate. This study aims to identify a synthetic blend of female metasternal gland compounds that could be used to attract R. prolixus. Results: We investigated the electrophysiological activity of the ten most abundant compounds in female R. prolixus metasternal glands using single sensillum recordings. In total we obtained 60 recordings from basiconic sensilla in male R. prolixus. In 31 of these recordings, responses to individual compounds were observed. Each of the ten tested compounds elicited neuron responses in a minimum of eight recordings. Having confirmed their electrophysiological activity, we tested these ten compounds by presenting them to male Rhodnius prolixus in a 7 olfactometer. Male bugs showed a significant preference for the blend of metasternal gland compounds compared to the clean air control. Conclusions: A simple blend of ten compounds found in female R. prolixus metasternal glands is attractive to conspecific males. All compounds in the blend are either commercially available at low cost, or easily synthetically prepared from simple precursors. We hope that this blend will be evaluated as a lure for pheromone traps in field bioassays.

  • 6. Gibb, A.R.
    et al.
    Suckling, D.M.
    El-Sayed, A.M.
    Bohman, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unelius, Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Dymock, J.J
    Larsen, M.L.
    Willoughby, B.E.
    (Z,E)-11,13-Hexadecadienyl Acetate: Sex Pheromone of the Grass Webworm Herpetogramma licarsisalis - Identification, Synthesis and Field Bioassays.2007In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 33, no 4, p. 839-47Article in journal (Refereed)
  • 7. Sunnerheim, Kerstin
    et al.
    Nordqvist, Annelie
    Nordlander, Göran
    Borg-Karlson, Anna-Karin
    Unelius, Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bohman, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nordenhem, Henrik
    Hellqvist, Claes
    Karlén, Anders
    Quantitative Structure -Activity Relationships of Pine Weevil Antifeedants, a Multivariate Approach2007In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 55Article in journal (Refereed)
  • 8.
    Unelius, C. Rikard
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bohman, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Lorenzo, Marcelo
    Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas. Centro de Pesquisas René Rachou/FIOCRUZ, Belo Horizonte, BRAZIL.
    Tröger, A
    Univ of Hamburg.
    Franke, S
    Univ of Hamburg.
    Francke, Wittko
    Univ of Hamburg.
    (4S,5S)-2,2,4-Triethyl-5-methyl-1,3-dioxolane: A New Volatile Released by a Triatomine Bug2010In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 12, no 24, p. 5601-5603Article in journal (Refereed)
    Abstract [en]

    Adults of the triatomine bug, Triatoma brasiliensis release 2,2,4-triethyl-5-methyl-1,3-dioxolane (1) as a mixture of the (4S,5S)- and (4R,5R)-enantiomers in a ratio of 4:1. Among the volatile acetals identified from insects so far, this is the first example resulting from an intermolecular condensation of a carbonyl moiety and a diol substructure.

  • 9.
    Unelius, C. Rikard
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Bohman, Björn
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Univ Western Australia, Australia.
    Nordlander, Goran
    Swedish University of Agricultural Sciences.
    Comparison of Phenylacetates with Benzoates and Phenylpropanoates as Antifeedants for the Pine Weevil, Hylobius abietis2018In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 66, no 44, p. 11797-11805Article in journal (Refereed)
    Abstract [en]

    This study concludes an extensive investigation of antifeedants for the pine weevil, Hylobius abietis (Coleoptera: Curculionidae), an economically important pest of planted conifer seedlings. Building on the previously reported antifeedant effects of benzoates and phenylpropanoids (aromatic compounds with one- or three-carbon-atom substituents on the benzene ring), we here report the antifeedant effects of compounds with two-carbon-atom side chains (i.e., phenylacetates). We also present new results; the best antifeedants from the benzoate class were tested at 10-fold lower concentrations in order to find the optimal antifeedants. Generally, for all three compound classes, efficient antifeedants were found to have one or two methyl, chloro, or methoxy substituents on the aromatic ring. For monosubstituted phenylpropanoids, the substituent preferably should be in the para-position. In the search for synergistic antifeedant effects among the three compound classes, combinations of compounds from the three classes were tested in binary and ternary mixtures.

  • 10.
    Unelius, C. Rikard
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Park, K. -C
    McNeill, M.
    Wee, S. L.
    Bohman, Björn
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Suckling, D. M.
    Identification and electrophysiological studies of (4S,5S)-5-hydroxy-4-methyl-3-heptanone and 4-methyl-3,5-heptanedione in male lucerne weevils2013In: Die Naturwissenschaften, ISSN 0028-1042, E-ISSN 1432-1904, Vol. 100, no 2, p. 135-143Article in journal (Refereed)
    Abstract [en]

    An investigation to identify a sex or aggregation pheromone of Sitona discoideus GyllenhAyenl (Coleoptera: Curculionidae) is presented. Antenna flicking and attraction behaviors evoked by conspecifics of both sexes were recorded in arena bioassays, where attraction of females to males was observed. Air entrainment of both males and females was conducted in separate chambers. Gas chromatographic-mass spectrometric analysis of headspace volatiles revealed that two male-specific compounds, 4-methyl-3,5-heptanedione (major) and (4S,5S)-5-hydroxy-4-methyl-3-heptanone (minor), were emitted during the autumnal post-aestivatory flight period. The stereoisomers of the minor component were separated by enantioselective gas chromatography and their absolute configurations assigned by NMR (diastereomers) and the known preference of enantioselective transesterification reactions catalyzed by Candida antarctica lipase B. Electroantennogram and single sensillum recording studies indicate that 4-methyl-3,5-heptanedione as well as all individual stereoisomers of 5-hydroxy-4-methyl-3-heptanone are detected by the antennae of male and female S. discoideus. Further, single sensillum recordings suggest that both sexes of S. discoideus have specialized olfactory receptor neurons (ORNs) for detecting 4-methyl-3,5-heptanedione and different populations of stereoselective ORNs for detecting the stereoisomers of 5-hydroxy-4-methyl-3-heptanone. Some of these stereoselective ORNs appear to be sex-specific in S. discoideus.

  • 11.
    Unelius, C. Rikard
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Schiebe, Christian
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Swedish University of Agricultural Sciences.
    Bohman, Björn
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Andersson, Martin N.
    Swedish University of Agricultural Sciences.
    Schlyter, Fredrik
    Swedish University of Agricultural Sciences.
    Non-Host Volatile Blend Optimization for Forest Protection against the European Spruce Bark Beetle, Ips typographus2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 1, article id e85381Article in journal (Refereed)
    Abstract [en]

    Conifer feeding bark beetles (Coleoptera, Curculionidae, Scolytinae) pose a serious economic threat to forest production. Volatiles released by non-host angiosperm plants (so called non-host volatiles, NHV) have been shown to reduce the risk of attack by many bark beetle species, including the European spruce bark beetle, Ips typographus. However, the most active blend for I. typographus, containing three green leaf volatiles (GLVs) in addition to the key compounds trans-conophthorin (tC) and verbenone, has been considered too expensive for use in large-scale management. To lower the cost and improve the applicability of NHV, we aim to simplify the blend without compromising its anti-attractant potency. Since the key compound tC is expensive in pure form, we also tested a crude version: technical grade trans-conophthorin (T-tC). In another attempt to find a more cost effective substitute for tC, we evaluated a more readily synthesized analog: dehydroconophthorin (DHC). Our results showed that 1-hexanol alone could replace the three-component GLV blend containing 1-hexanol, (3Z)-hexen-1-ol, and (2E)-hexen-1-ol. Furthermore, the release rate of tC could be reduced from 5 mg/day to 0.5 mg/day in a blend with 1-hexanol and (-)-verbenone without compromising the anti-attractant activity. We further show that T-tC was comparable with tC, whereas DHC was a less effective anti-attractant. DHC also elicited weaker physiological responses in the tC-responding olfactory receptor neuron class, providing a likely mechanistic explanation for its weaker anti-attractive effect. Our results suggest a blend consisting of (-)-verbenone, 1-hexanol and technical trans-conophthorin as a cost-efficient anti-attractant for forest protection against I. typographus.

  • 12. Vitta, A.C.R.
    et al.
    Bohman, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unelius, C. Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Lorenzo, Marcelo
    Behavioral and Electrophysiological Responses of Triatoma brasiliensis Males to Volatiles Produced in the Metasternal Glands of Female2009In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 35, no 10, p. 1212-1221Article in journal (Refereed)
    Abstract [en]

    In many insects, mate finding is mediated by volatile sex pheromones, but evidence for this phenomenon in triatomines (Heteroptera: Reduviidae) is still fragmentary. Recently, it was shown that metasternal glands (MGs) are involved in producing signals related to the sexual communication of Triatoma infestans and Rhodnius prolixus. Based on this, we tested whether MG volatiles could be involved in the sexual communication of Triatoma brasiliensis. Odor-mediated orientation responses were studied by using a T-tube olfactometer. These tests showed that males exhibit positive anemotaxis when confronted with adult odor-laden air currents. Moreover, females that had their metasternal glands occluded did not elicit significant orientation by males. Compounds produced by the MGs of T. brasiliensis females were identified by means of SPME, GC-FID, and GC-MS, with achiral and chiral columns. All substances identified were ketones and alcohols, and similar compound profiles were found in the secretions produced by both sexes. The most abundant compounds identified were 3-pentanone, followed by (4R)-methyl-1-heptanol, 3-pentanol, and (2S)-methyl-1-butanol. In addition, GC-EAD recordings showed that the antennae of males responded to several of the main components of female MG secretions. Our results showed that compounds produced by the MGs of T. brasiliensis females are involved in the sexual communication of this species.

  • 13.
    Zhao, Tao
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. KTH Royal Instute of Technology, Sweden;Örebro University, Sweden.
    Ganji, Suresh
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Bohman, Björn
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. University of Western Australia, Australia.
    Weinstein, Philip
    University of Adelaide, Australia.
    Krokene, Paal
    Norwegian Institute of Bioeconomy Research, Norway.
    Borg-Karlsson, Anna-Karin
    KTH Royal Instute of Technology, Sweden.
    Unelius, C. Rikard
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Convergent evolution of semiochemicals across Kingdoms: bark beetles and their fungal symbionts2019In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 13, no 6, p. 5-1545Article in journal (Refereed)
    Abstract [en]

    Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Treekilling bark beetles vector numerous symbiotic blue-stain fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1] nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with 13C D-Glucose, the fungus Grosmannia europhioides incorporated 13C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.

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