Chemical basis of anti-listerial effects of rosemary herb during stomaching with fresh-cut vegetables

Fresh rosemary herb has demonstrated much stronger anti-listerial effects when stomached with contaminated fresh-cut vegetables than those obtained by application of rosemary essential oils. Various types of rosemary extracts (hydrodistillates, CO₂ extracts, hexane/acetone extracts) were analysed by GC–MS and tested for anti-listerial effects in vitro. Principal component analysis showed that verbenone levels were most correlated with anti-listerial effects, followed by levels of camphor. Stomaching rosemary herb greatly increased headspace levels of verbenone and camphor (by up to 20 times) compared to intact or chopped fresh rosemary. It is speculated that by crushing the herb under water, stomaching released enhanced levels of these components as lipophilic nanosomes which rapidly migrated to lipophilic surfaces, including the membranes of Listeria cells.     

Acetophenone as an Anti-attractant for the Western Pine Beetle, <Emphasis Type="Italic">Dendroctonus Brevicomis</Emphasis> LeConte (Coleoptera: Scolytidae)

Host location and colonization by bark beetles is dependent upon the relative and absolute amounts of attractant and antiattractant compounds available. Many investigations have lead to use of antiattractants for the management of these pests and have been especially focused on verbenone. However, recent studies have identified new antiattractants for several species of bark beetles. We report results of recent investigations of the response of western pine beetle, Dendroctonus brevicomis LeConte, to two recently identified antiattractants, acetophenone, and fenchyl alcohol, with verbenone as a standard of comparison, in northern California. Release of both acetophenone and verbenone resulted in significantly lower trap catches of D. brevicomis in aggregation pheromone-baited traps, while fenchyl alcohol was inactive. Acetophenone was the only antiattractant that did not reduce numbers of the most abundant predator of D. brevicomis, Temnochila chlorodia (Mannerheim), responding to the attractant pheromone of its prey. Aggregation pheromone-baited traps with acetophenone also had the highest predator/prey ratio. Our results suggest that acetophenone may be part of the intra- and interspecific interactions among sympatric species of bark beetles and may have application in their control.     

Electrophysiological and Behavioral Responses of <Emphasis Type="Italic">Ips subelongatus</Emphasis> to Semiochemicals from Its Hosts,Non-hosts,and Conspecifics in China

Volatiles from hosts, non-hosts, interspecifics, and conspecifics of the Asian larch bark beetle, Ips subelongatus Motsch., were analyzed using both gas chromatographic-electroantennographic detection (GC-EAD) and gas chromatography/mass spectrometry (GC-MS) techniques, and field trapping bioassays in Inner Mongolia, China. GC-EAD experiments indicated that I. subelongatus antennae (both sexes) strongly responded not only to the major male-produced conspecific components, ipsenol, and ipsdienol, but also to other bark beetle compounds (cis-verbenol and verbenone), host monoterpenes (α-pinene, β-pinene, and para-cymene) from Larix sp. logs, and non-host leaf (green leaf volatiles and geranyl acetone) and bark (C₈-alcohols and trans-conophthorin) volatiles. Repeatable EAD responses were also found to two compounds from hindgut extracts that are undetectable by GC. One of these minor compounds was identified as amitinol. Field trapping experiments showed that the EAD-active, major male-hindgut component, racemic ipsenol, is the only individual compound that significantly attracted both sexes of I. subelongatus, whereas all other compounds, including previously reported pheromone components of European Ips cembrae, ipsdienol and 3-methyl-3-buten-1-ol, were unattractive. Ipsdienol, 3-methyl-3-buten-1-ol, or their binary blend had no synergistic or antagonistic effects on I. subelongatus attraction when combined with ipsenol, whereas cis-verbenol (a synomone) and verbenone (the antiaggregation semiochemical) inhibited its attraction to the ipsenol-containing attractive blend. A mixture of three EAD-active host monoterpenes, α-pinene, β-pinene, and para-cymene, was unattractive, but interrupted the pheromone response of I. subelongatus. Geranyl acetone, one of the strong EAD-active non-host volatiles also significantly reduced the number of I. subelongatus captured in traps baited with ipsenol-containing attractive blend. Our results add support to the recent phylogenetic finding that European and Asian larch bark beetles should be regarded as two distinct species: I. cembrae infecting larch in Europe and I. subelongatus infesting larch in Asia.     

Transformations of monoterpenoid ketones in supercritical isopropanol/CO2 in a continuous flow reactor in the presence of alumina. Competitive reduction of olefinic double bond and carbonyl group

Reactivity of monoterpenoid α,β-unsaturated ketones (carvone, verbenone and pinocarvone) in binary supercritical solvent isopropanol/CO₂ in a flow reactor in the presence of granular Al₂O₃ was studied. Competitive reduction of olefinic double bond and carbonyl group was observed at the first reaction step. Subsequent transformation of intermediate products – alcohols – enables single step production of polyunsaturated monoterpenes 1,5,8-p-mentatriene and verbenene from carvone and verbenone, respectively, at contact times of several minutes.