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Guerin, Patrick

Nom
Guerin, Patrick
Affiliation principale
Site web
Fonction
Professeur associƩ
Email
patrick.guerin@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/310

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  • Publication
    AccĆØs libre
    Components from Sri Lankan Piper betle L. leaf oil and their analogues showing toxicity against the housefly, Musca domestica
    (2007)
    Mohottalage, Susantha
    ;
    Tabacchi, Raffaele 
    ;
    Guerin, Patrick 
    The essential oil extracted from Piper betle L. leaf using pilot plant steam distillation was tested against the adult housefly, Musca domestica, for insecticidal activity. LC50 values at the end of 24 and 48 h exposure periods were 10.3 and 8.7 mg/dm3, respectively. Ceylon citronella oil (Cymbopogon nardus) used as a standard showed LC50s of 26.5 and 24.2 mg/dm3 for the same exposure periods. Bioassay-guided fractionation of P. betle leaf oil revealed safrole and eugenol as the active principles against M. domestica, safrole showing LC50 values of 4.8 and 4.7 mg/dm3, and eugenol 7.3 and 6.2 mg/dm3 for the 24 and 48 h exposure periods, respectively, while citronellal (synthetic standard) showed equal LC50 values of 14.3 mg/dm3 for the same exposure periods. Using safrole as the starting compound, eight analogues were prepared to study structureā€“activity relationships. Among the eight analogues, dihydrosafrole gave almost equal mortality at LC50 4.7 mg/dm3 as that of the parent compound safrole after 24 and 48 h exposure, but isosafrole was twice as active as safrole, showing LC50 values of 2.3 and 2.2 mg/dm3 for the 24 and 48 h exposure periods. Our GCā€“MS studies on Sri Lankan P. betle leaf oil show that it contains safrole (52.7%), allylpyrocatechol diacetate (15.4%), eugenol (6.4%) and eugenyl acetate (5.8%) as the major components. Here we also present the GCā€“MS profile of fractions of Sri Lankan P. betle leaf oil.
  • Publication
    AccĆØs libre
    (1S,3S,7R)-3-methyl-Ī±-himachalene from the male sandfly Lutzomyia longipalpis (Diptera: Psychodidae) induces neurophysiological responses and attracts both males and females
    (2005)
    Spiegel, C.N.
    ;
    Jeanbourquin, Philippe 
    ;
    Guerin, Patrick 
    ;
    Hooper, A.M.
    ;
    Claude, S.
    ;
    Tabacchi, Raffaele 
    ;
    Sano, S.
    ;
    Mori, K.
    Lutzomyia longipalpis adult males form leks on or near hosts and release (1S,3S,7R)-3-methyl-Ī±-himachalene from their tergal glands to lure females to the same site for mating and feeding. Here we have examined whether the male-produced attractant could also serve as a male aggregation stimulus. High resolution chiral capillary gas chromatography analysis of male tergal gland extracts, synthetic (1S,3S,7R)-3-methyl-Ī±-himachalene, and a synthetic mixture of all isomers of 3-methyl-Ī±-himachalene, was coupled to electrophysiological recordings from ascoid sensillum receptor cells in antennae of male and female sandflies. Receptor cells of both sexes responded only to the main component of the male tergal gland extract that eluted at the same retention time as (1S,3S,7R)-3-methyl-Ī±-himachalene. Furthermore, of the eight 3-methyl-Ī±-himachalene isomers in the synthetic mixture only the fraction containing (1S,3S,7R)-3-methyl-Ī±-himachalene, co-eluting with an isomer of (1S*,3S*,7S*)-3-methyl-Ī±-himachalene, elicited an electrophysiological response from male and female ascoid sensillum receptor cells. Both males and females flew upwind in a wind tunnel towards a filter paper disk treated with either 4ā€“6 male equivalents of the tergal gland extract, pure (1S,3S,7R)-3-methyl-Ī±-himachalene or the synthetic mixture of eight isomers. This indicates that (1S,3S,7R)-3-methyl-Ī±-himachalene derived from L. longipalpis males may have a dual function in causing male aggregation as well as serving as a sex pheromone for females.