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PubMed1984

Metabolism of alpha-terpineol by Pseudomonas incognita.

Details of the metabolism of alpha-terpineol by Pseudomonas incognita are presented. Degradation of alpha-terpineol by this organism resulted in the formation of a number of acidic and neutral metabolites. Among the acidic metabolites, beta-isopropyl pimelic acid, 1-hydroxy-4-isopropenyl-cyclohexane-1-carboxylic acid, 8-hydroxycumic acid, oleuropeic acid, cumic acid, and p-isopropenyl benzoic acid have been identified. Neutral metabolites identified were limonene, p-cymene-8-ol, 2-hydroxycineole, and uroterpenol. Cell-free extracts prepared from alpha-terpineol adapted cells were shown to convert alpha-terpineol, p-cymene-8-ol, and limonene to oleuropeic acid, 8-hydroxycumic acid, and perillic acid, respectively, in the presence of NADH. The same cell-free extract contained NAD+ -specific dehydrogenase(s) which converted oleuropyl alcohol, p-cymene-7,8-diol, and perillyl alcohol to their corresponding 7-carboxy acids. On the basis of various metabolites isolated from the culture medium, together with the supporting evidence obtained from enzymatic and growth studies, it appears that P. incognita degrades alpha-terpineol by at least three different routes. While one of the pathways seems to operate via oleuropeic acid, a second may be initiated through the aromatization of alpha-terpineol. The third pathway may involve the formation of limonene from alpha-terpineol and its further metabolism.

Chromatography, Gas↗
PubMed2004

New monoterpene glucoside from the aerial parts of thyme (Thymus vulgaris L.).

A new monoterpene glucoside (1) was isolated from a methanol extract of the dried aerial parts of thyme (Thymus vulgaris L.), together with known 2- and 5-beta-D-glucopyranosylthymoquinols (2 and 3, respectively), and (-)-angelicoidenol-beta-D-glucopyranoside (4). The structure of 1 was elucidated to be (R)-p-cymen-9-yl beta-D-glucopyranoside by spectral evidence and enantioselective synthesis from (R)- and (S)-p-cymen-9-ol derived from p-cymen-8-ol.

Glucosides↗
PubMed1996

Gas chromatographic-mass spectrometric method to characterise the transfer of dietary odorous compounds into plasma and milk.

The flavours contained in a mammalian mother's milk can exert a marked influence on her offspring's proximate suckling behaviour and later preferences. The aim of this study was to establish a reliable analytical procedure to characterise the mammary transfer of selected volatile constituents of maternal food from non-pregnant and recently parturient ewes. Six known volatile compounds, most representative of cumin aroma (alpha-pinene, gamma-terpinene, cuminaldehyde, p-cymene, limonene and cineole), were traced in the blood and milk of ewes fed with cumin seeds, using liquid-liquid extraction combined with gas chromatography-specific ion monitoring mass spectrometry. Among the six cumin odour markers, only one, p-cymene, was transferred in quantifiable amounts into the venous plasma. The other cumin markers could only be detected as traces corresponding to amounts lower that the limit of quantification. In milk, four of the cumin markers could be detected, and two of these were quantified.

Animals↗
PubMed2003

Antimicrobial and antioxidant activity of the essential oil and methanol extracts of Thymus pectinatus Fisch. et Mey. Var. pectinatus (Lamiaceae).

The essential oil, obtained by using a Clevenger distillation apparatus, and water-soluble (polar) and water-insoluble (nonpolar) subfractions of the methanol extract of Thymus pectinatus Fisch. et Mey. var. pectinatus were assayed for their antimicrobial and antioxidant properties. No (or slight) antimicrobial activity was observed when the subfractions were tested, whereas the essential oil showed strong antimicrobial activity against all microorganisms tested. Antioxidant activities of the polar subfraction and the essential oil were evaluated using 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical, superoxide radical scavenging, and lipid peroxidation assays. The essential oil, in particular, and the polar subfraction of the methanol extract showed antioxidant activity. The essential oil was analyzed by GC/MS, and 24 compounds, representing 99.6% of the essential oil, were identified: thymol, gamma-terpinene, p-cymene, carvacrol, and borneol were the main components. An antimicrobial activity test carried out with fractions of the essential oil showed that the activity was mainly observed in those fractions containing thymol, in particular, and carvacrol. The activity was, therefore, attributed to the presence of these compounds. Other constituents of the essential oil, such as borneol, gamma-terpinene, and p-cymene, could be also taken into account for their possible synergistic or antagonistic effects. On the other hand, thymol and carvacrol were individually found to possess weaker antioxidant activity than the crude oil itself, indicating that other constituents of the essential oil may contribute to the antioxidant activity observed. In conclusion, the results presented here show that T. pectinatus essential oil could be considered as a natural antimicrobial and antioxidant source.

Anti-Bacterial Agents↗
PubMed2006

Synthesis, characterization, and in vitro evaluation of novel ruthenium(II) eta6-arene imidazole complexes.

Ten complexes of general formula [Ru(eta6-arene)Cl2(L)], [Ru(eta6-arene)Cl(L)2][X], and [Ru(eta6-arene)(L)3][X]2 (eta6-arene = benzene, p-cymene; L = imidazole, benzimidazole, N-methylimidazole, N-butylimidazole, N-vinylimidazole, N-benzoylimidazole; X = Cl, BF4, BPh4) have been prepared and characterized by spectroscopy. The structures of five representative compounds have been established in the solid state by single-crystal X-ray diffraction. All the new compounds were assessed by the same in vitro screening assays applied to [imidazole-H][trans-RuCl4(DMSO)(imidazole)] (NAMI-A) and [Ru(eta6-arene)Cl2(1,3,5-triaza-7-phosphaadamantane)] (RAPTA) compounds. It was found that the new compounds show essentially the same order of cytotoxicity as the RAPTA compounds toward cancer cells. Several of the compounds were selective toward cancer cells in that they were less (or not) cytotoxic toward nontumorigenic cells that are used to model healthy human cells. Thus, two of the compounds, [Ru(eta6-p-cymene)Cl(vinylimid)2][Cl] (vinylimid = N-vinylimidazole) and [Ru(eta6-benzene)(mimid)3][BF4]2 (mimid = N-methylimidazole), have been selected for a more detailed in vivo evaluation.

Animals↗
PubMed2002

Isolation and structure elucidation of radical scavengers from Thymus vulgaris leaves.

2,2-Diphenyl-1-picrylhydrazyl radical (DPPH*) scavenging activity-guided fractionation of a leaf extract of Thymus vulgaris led to the isolation of the radical scavengers rosmarinic acid 1, eriodictyol, taxifolin, luteolin 7-glucuronide, p-cymene 2,3-diol, p-cymene 2,3-diol 6-6'-dimer, carvacrol, thymol, and a new compound, 2. The fractionation was considerably facilitated by using an on-line HPLC detector for radical scavenging activity. In this detector activity is monitored as the disappearance of the color of a postcolumn added stable radical after reacting with radical scavengers in a reaction coil. Compound 2, which consists of rosmarinic and caffeic acid moieties linked via a C-3'-C-8' ' ether bridge, was mainly elucidated by various NMR techniques and CD. Phenylpropanoid trimer 2 was a weaker and stronger radical scavenger than rosmarinic acid 1 in off-line TEAC and DPPH* assays, respectively.

Biphenyl Compounds↗
PubMed2006

Conflicting demands on detoxification pathways influence how common brushtail possums choose their diets.

Most herbivores eat more and survive better when they have access to a variety of foods. One explanation involves the detoxification of plant secondary metabolites (PSMs). By feeding from a variety of plants that contain different classes of PSMs, animals can use multiple detoxification pathways and presumably consume more food. Although popular, this theory is difficult to test because it requires knowledge of the detoxification pathways of each PSM in the diet. We established that common brushtail possums (Trichosurus vulpecula) use various combinations of oxidation, hydrolysis, and conjugation with glucuronic acid (GA) or glycine to detoxify six PSMs. Compared to their ingestion of a single PSM, possums ate more when offered a choice between two diets containing PSMs that require apparently independent detoxification pathways (benzoate and 1,8-cineole, benzoate and p-cymene, benzoate and orcinol, benzoate and salicin, or orcinol and 1,8-cineole). However, possums still did not eat as much of these diets as they did of a basal diet free of PSMs. This suggests that detoxification pathways are never independent, but are separated instead by degrees. In contrast, possums offered a choice of two PSMs that require competing detoxification pathways (1,8-cineole and p-cymene, 1,8-cineole and salicin, or orcinol and salicin) ate no more than when offered diets containing one of the compounds. There was an exception: even though both rutin and orcinol are detoxified via conjugation with GA, the feeding behavior of possums did not suggest competition for detoxification pathways. This implies that the supply of GA is not limiting. This study provides the first convincing evidence that herbivorous mammals can eat more by selecting mixed diets with a diversity of PSMs that make full use of their detoxification potential. It also emphasizes that other behavioral and physiological factors, such as transient food aversions, influence feeding behavior.

Animals↗
PubMed2005

Increase in activity of essential oil components carvacrol and thymol against Escherichia coli O157:H7 by addition of food stabilizers.

The major components of oregano and thyme essential oils that had previously been shown to inhibit Escherichia coli O157:H7 were determined by high-performance liquid chromatography with UV detection and liquid chromatographic tandem mass spectrometry. The MICs and MBCs of carvacrol, thymol, p-cymene, and gamma-terpinene against a strain of E. coli O157: H7 phage type 34 isolated from bovine feces were determined by microdilution assay. The constituents were then tested in checkerboard assays to detect possible interactions. Carvacrol and thymol displayed bacteriostatic and bactericidal properties with MICs of 1.2 mmol/liter and were additive in combination. p-Cymene and gamma-terpinene displayed no measurable antibacterial activity up to 50 mmol/liter, and neither influenced the activity of carvacrol or thymol. Growth curves in the presence of nonlethal concentrations of carvacrol with the addition of agar (0.05%, wt/vol) or carrageenan (0.125%, wt/vol) as stabilizer were produced by optical density measurement. The stabilizers agar and carrageenan both significantly improved the effectiveness of carvacrol in broth, possibly because of a delay in the separation of the hydrophobic substrate from the aqueous phase of the medium. When carvacrol was dissolved in ethanol before addition to broth, stabilizers were not needed. Carvacrol and thymol, particularly when used in combination with a stabilizer or in an ethanol solution, may be effective in reducing the number or preventing growth of E. coli O157:H7 in liquid foods.

Agar↗
PubMed2001

Effects of volatile oil constituents of Nigella sativa on carbon tetrachloride-induced hepatotoxicity in mice: evidence for antioxidant effects of thymoquinone.

Effects of the volatile oil constituents of Nigella sativa, namely, thymoquinone (TQ), p-cymene and alpha-pinene, on carbon tetrachloride (CCl4-indued acute liver injury were investigated in mice. A single dose of CCl4 (15 microl/Kg i.p.) induced hepatotoxicity 24 h after administration manifested biochemically as significant elevation of the enzymes activities of serum alanine transaminase (ALT, EC:2.6.1.2), asparate transaminase (AST, EC:2.6.1.1) and lactate dehydrogenase (LDH, EC: 1.1.1.27). The toxicity was further evidenced by a significant decrease of non-protein sulfhydryl(-SH) concentration, and a significant increase of lipid peroxidation measued as malondialdhyde (MDA) in the liver tissues. Administration of different doses of the TQ (4, 8, 12.5, 25 and 50 mg/Kg i.p.) did not alter the chosen biochemical parameters measured, while higher doses of TQ were lethal. The LD50 was 90.3 mg/Kg (77.9-104.7, 95% CL). Pretreatment of mice with different doses of TQ 1 h before CCl4 injection showed that the only dose of TQ that ameliorated hepatotoxicity of CCl4 was 12.5 mg/Kg i.p. as evidenced by the significant reduction of the elevated levels of serum enzymes as well as hepatic MDA content and significant increase of the hepatic nonprotein sulfhydryl(-SH) concentration. Treatment of mice with the other volatile oil constituents, p-cymene or alpha-pinene did not induce any changes in the serum ALT measured. In addition, i.p. administration of these compounds 1 h before CCl4 injection, did not protect mice against CC4-induced hepatotoxicity. The results of the present study indicate that TQ (12.5 mg/Kg, i.p.) may play an important role as antioxidant and may efficiently act as a protective agent against chemically-induced hepatic damage. In contrast, higher doses of TQ were found to induce oxidative stress leading to hepatic injury.

Alanine Transaminase↗
PubMed2006

Identification and expression of the cym, cmt, and tod catabolic genes from Pseudomonas putida KL47: expression of the regulatory todST genes as a factor for catabolic adaptation.

Pseudomonas putida KL47 is a natural isolate that assimilates benzene, 1-alkylbenzene (C(1)-C(4)), biphenyl, p-cumate, and p-cymene. The genetic background of strain KL47 underlying the broad range of growth substrates was examined. It was found that the cym and cmt operons are constitutively expressed due to a lack of the cymR gene, and the tod operon is still inducible by toluene and biphenyl. The entire array of gene clusters responsible for the catabolism of toluene and p-cymene/p-cumate has been cloned in a cosmid vector, pLAFR3, and were named pEK6 and pEK27, respectively. The two inserts overlap one another and the nucleotide sequence (42,505 bp) comprising the cym, cmt, and tod operons and its flanking genes in KL47 are almost identical (>99%) to those of P. putida F1. In the cloned DNA fragment, two genes with unknown functions, labeled cymZ and cmtR, were newly identified and show high sequence homology to dienelactone hydrolase and CymR proteins, respectively. The cmtR gene was identified in the place of the cmtI gene of previous annotation. Western blot analysis showed that, in strains F1 and KL47, the todT gene is not expressed during growth on Luria Bertani medium. In minimal basal salt medium, expression of the todT gene is inducible by toluene, but not by biphenyl in strain F1; however, it is constantly expressed in strain KL47, indicating that high levels of expression of the todST genes with one amino acid substitution in TodS might provide strain KL47 with a means of adaptation of the tod catabolic operon to various aromatic hydrocarbons.

Amino Acid Sequence↗
PubMed2001

Essential oil composition of sea fennel (Crithmum maritimum) form Turkey.

Constituents of essential oils of sea fennel (Crithmum maritimum L.) collected in different localities of Turkey in 1997 and 1998 have been identified by GC/MS. The effects of collection time and locality on the oil content and composition have been studied. The samples were classified into groups according to the main components: sabinene, gamma-terpiene, methyl thymol and terpinen-4-ol; gamma-terpinene, dill apiol and sabinene; gamma-terpiene, methyl thymol and limonene; p-cymene, methyl thymol and gamma-terpinen. (Z)-beta-ocimene and spathulenol were found with high percentage values in some samples. cis-p-Menth-4-en-1,2-diol was identified in only one oil. Early collected plants yielded oil rich in p-cymene. Effect of freezing plant did not have any important effect in oil composition.

Apiaceae↗
PubMed2004

Heteronuclear rhodium, palladium, platinum, and gold organoimido complexes from dinuclear organoamido rhodium precursors.

Treatment of the organoamido complexes [Rh(2)(mu-4-HNC(6)H(4)Me)(2)(L(2))(2)] (L(2) = 1,5-cyclooctadiene (cod), L = CO) with nBuLi gave solutions of the organoimido species [Li(2)Rh(2)(mu-4-NC(6)H(4)Me)(2)(L(2))(2)]. Further reaction of [Li(2)Rh(2)(mu-4-NC(6)H(4)Me)(2)(cod)(2)] with [Rh(2)(mu-Cl)(2)(cod)(2)] afforded the neutral tetranuclear complex [Rh(4)(mu-4-NC(6)H(4)Me)(2)(cod)(4)] (2), which rationalizes the direct syntheses of 2 from [Rh(2)(mu-Cl)(2)(cod)(2)] and Li(2)NC(6)H(4)Me. Reactions of [Li(2)Rh(2)(mu-4-NC(6)H(4)Me)(2)(CO)(4)] with chloro complexes such as [Rh(2)(mu-Cl)(2)(CO)(4)], [MCl(2)(cod)] (M = Pd, Pt), and [Ru(2)(mu-Cl)(2)Cl(2)(p-cymene)(2)] afforded the homo- and heterotrinuclear complexes PPN[Rh(3)(mu-4-NC(6)H(4)Me)(2)(CO)(6)] (5; PPN=bis(triphenylphosphine)iminium), [(CO)(4)Rh(2)(mu-4-NC(6)H(4)Me)(2)M(cod)] (M = Pd (6), Pt(7)) and [(CO)(4)Rh(2)(mu-4-NC(6)H(4)Me)(2)Ru(p-cymene)] (8), while the reaction with [AuCl(PPh(3))] gave the tetranuclear compound [(CO)(4)Rh(2)(mu--4-NC(6)H(4)Me)(2)[Au(PPh(3))](2)] (9). The structures of complexes 6, 8, and 9 were determined by X-ray diffraction studies. The anion of 5 reacts with [AuCl(PPh(3))] to give the butterfly cluster [[Rh(3)(mu-4-NC(6)H(4)Me)(2)(CO)(6)]Au(PPh(3))] (10), in which the Au atom is bonded to two rhodium atoms. Reaction of the anion of 5 with [Rh(cod)(NCMe)(2)](BF(4)) gave the tetranuclear complex [Rh(4)(mu-4-NC(6)H(4)Me)(2)(CO)(6)(cod)] (11) in which the Rh(cod) fragment is pi-bonded to one of the arene rings, while the reaction of the anion of 5 with [PdCl(2)(cod)] afforded the heterotrinuclear complex 6 through a metal exchange process.

Journal Article↗
PubMed2005

Preparation, structure, and ethylene polymerization behavior of half-sandwich picolyl-functionalized carborane iridium, ruthenium, and rhodium complexes.

The synthesis of half-sandwich transition-metal complexes containing the Cab(N) and Cab(N,S) chelate ligands (HCab(N) = HC2B10H10CH2C5H4N (1), LiCab(N,S) = LiSC2B10H10CH2C5H4N (4)) is described. Compounds 1 and 4 were treated with chloride-bridged dimers [{Ir(Cp*)Cl2}2] (Cp* = eta5-C5Me5), [{Ru(p-cymene)Cl2}2] and [{Rh(Cp*)Cl2}2] to give half-sandwich complexes [Ir(Cp*)Cl(Cab(N))] (2), [Ru(p-cymene)Cl(Cab(N))] (3), and [Rh(Cp*)Cl(Cab(N,S))] (5), respectively. Addition reaction of LiCab(S) (Cab(S) = SC2(H)B10H10) to the rhodium complex 5 yields [Rh(Cp*)(Cab(S))(Cab(N,S))] (6). All the complexes were characterized by IR and NMR spectroscopy, and by elemental analysis. In addition, X-ray structure analyses were performed on complexes 2, 3, 5, and 6, in which the potential C,N- and N,S-chelate ligands were found to coordinate in a bidentate mode. The carborane complex 2 shows catalytic activities up to 3.7x10(5) g PE mol(-1) Ir h(-1) for the polymerization of ethylene in the presence of methylaluminoxane (MAO) as cocatalyst. The polymer obtained from this homogeneous catalytic reaction has a spherical morphology. Catalytic activities and the molecular weight of polyethylene have been investigated for various reaction conditions.

Journal Article↗
PubMed2006

Utilization of self-sorting processes to generate dynamic combinatorial libraries with new network topologies.

The synthesis of water-soluble, organometallic macrocycles is described. They were obtained by self-assembly in reactions of the half-sandwich complexes [[Ru(C6H5Me)Cl2]2], [[Ru(p-cymene)Cl2]2], [[Rh(Cp)Cl2]2], and [[Ir(Cp*)Cl2]2] with the ligand 5-dimethylaminomethyl-3-hydroxy-2-methyl-4-(1H)-pyridone in buffered aqueous solution at pH 8. The structure of the Ru-(p-cymene) complex was determined by single-crystal X-ray crystallography. Upon mixing, these complexes undergo scrambling reactions to give dynamic combinatorial libraries. In combination with structurally related complexes based on amino-methylated 3-hydroxy-2-(1H)-pyridone ligands, an exchange of metal fragments but no mixing of ligands was observed. This self-sorting behavior was used to construct dynamic combinatorial libraries of macrocycles, in which two four-component sub-libraries are connected by two common building blocks. This type of network topology influences the adaptive behavior of the library as demonstrated in selection experiments with lithium ions as the target.

Journal Article↗
PubMed2007

Preparation and structure of mono- and binuclear half-sandwich iridium, ruthenium, and rhodium carbene complexes containing 1,2-dichalcogenolao 1,2-dicarba-closo-dodecaboranes.

The synthesis of half-sandwich transition metal complexes containing both 1,2-dichalcogenolato-1,2-dicarba-closo-docecaborane (Cab(E,E)) [Cab(E,E)=E(2)C(2)(B(10)H(10)); E = S, Se] and N-heterocyclic carbene (NHC) ligands is described. Addition of mono-NHC ligand to the 16e half-sandwich dichalcogenolato carborane complexes [Cp*Rh(Cab(E,E))], [Cp*Ir(Cab(S,S))], [(p-cymene)Ru(Cab(S,S))] (Cp* = pentamethylcyclopentadienyl) gives corresponding mononuclear 18e dithiolate complexes of the type [LM(Cab(E,E))(NHC)]: [Cp*M(Cab(S,S))(1-ethenyl-3-methylimidazolin-2-ylidene)] (M = Ir (2), Rh (3)), [Cp*Rh(Cab(E,E))(3-methyl-1-picolyimidazolin-2-ylidene)] [E = S (6), Se (7)], [(p-cymene)Ru(Cab(S,S))(NHC)] [NHC = 1-ethenyl-3-methylimidazolin-2-ylidene (4), 3-methyl-1-picolyimidazolin-2-ylidene (8)], whereas bis-NHC give centrosymmetric binuclear complexes [{Cp*M(Cab(S,S))}(2)(1,1'-dimethyl-3,3'-methylene(imidazolin-2-ylidene))] [M = Rh (10), Ir (11)]. The complexes were characterized by IR, NMR spectroscopy and elemental analysis. In addition, X-ray structure analyses were performed on complexes 2-4, 6, 8, 10 and 11.

Journal Article↗
PubMed2007

Chemical composition and antimicrobial activity of the essential oils from two species of Eucalyptus.

The leaf-essential oil from Eucalyptus robusta and E. saligna, the latter in two phenologic stages, were analysed by gas chromatography coupled to mass spectrometry (GC-MS). The major constituent in E. robusta oil was the monoterpene alpha-pinene (73.0% of the total amount). The oil composition of the E. saligna was dependent of the phenologic stage. In the vegetative phase, the major constituents were p-cymene (54.2%) and gamma-terpinene (43.8%), while during the blossoming alpha-pinene became the major constituent followed by p-cymene (22.5%). Additionally, the antimicrobial activity for all three oils was evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. The E. robusta oil presented the highest growth inhibition for all the microorganisms tested.

Anti-Infective Agents↗
PubMed1988

Bacterial metabolism of side chain fluorinated aromatics: cometabolism of 4-trifluoromethyl(TFM)-benzoate by 4-isopropylbenzoate grown Pseudomonas putida JT strains.

Enzymes of the p-cymene pathway in Pseudomonas putida strains cometabolized the intermediate analogue 4-trifluoromethyl(TFM)benzoate. Three products, 4-TFM-2,3-dihydro-2,3-dihydroxybenzoate, 4-TFM-2,3-dihydroxybenzoate and 2-hydroxy-6-oxo-7,7,7-trifluorohepta-2,4-dienoate (7-TFHOD) were identified chemically and by spectroscopic properties. Certain TFM-substituted analogue metabolites of the p-cymene pathway were transformed at drastically reduced rates. Hammett type analysis of ring cleavage reactions of 4-substituted 2,3-dihydroxybenzoates revealed the negative inductive and especially mesomeric effect of substituents to be rate determining. Whereas decarboxylation of 3-carboxy-7-TFHOD was not affected by fluorine substitution the subsequent hydrolysis of 7-TFHOD proceeded very slowly. The negative inductive effect of the TFM-group probably inhibited heterolysis of the carbon bond between C5 and C6 of 7-TFHOD.

Benzoates↗
PubMed2007

Electrophysiological and behavioral responses of Ips subelongatus 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 (alpha-pinene, beta-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, alpha-pinene, beta-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.

Acyclic Monoterpenes↗