Bioorganic Diversity of Rare Coriandrum sativum L. Honey: Unusual Chromatographic Profiles Containing Derivatives of Linalool/Oxygenated Methoxybenzene

The compounds responsible for highly individual aroma profile of Coriandrum sativum L. honey were isolated by headspace solid‐phase microextraction (HS‐SPME; used fibers: A: polydimethylsiloxane (PDMS)/divinylbenzene (DVB) and B: divinylbenzene/carboxen/polydimethylsiloxane), as well as ultrasonic solvent extraction (USE; used solvents: A: pentane/Et₂O 1 : 2 (v/v) and B: CH₂Cl₂) and analyzed by gas chromatography (GC) and mass spectrometry (MS). Unusual chromatographic profiles were obtained containing derivatives of linalool/oxygenated methoxybenzene. trans‐Linalool oxide (11.1%; 14.6%) dominated in the headspace, followed by other linalool derivatives (such as cis/trans‐anhydrolinalool oxide (5.0%; 5.9%), isomers of lilac aldehyde/alcohol (14.9%; 13.8%) or p‐menth‐1‐en‐9‐al (15.6%; 18.5%)), octanal, and several low‐molecular‐weight esters. The major compounds in the solvent extracts were oxygenated methoxybenzene derivatives such as 3,4,5‐trimethoxybenzyl alcohol (26.3%; 24.7%), methyl syringate (23.8%; 11.7%), and 3,4‐dimethoxybenzyl alcohol (5.6%; 13.9%). Another group of abundant compounds in the extracts were derivatives of linalool (e.g., (E)/(Z)‐2,6‐dimethylocta‐2,7‐diene‐1,6‐diol (17.8%; 16.1%)). Among the compounds identified, cis/trans‐anhydrolinalool oxides and 3,4,5‐trimethoxybenzyl alcohol can be useful as chemical markers of coriander honey.     

Influence of volatile compounds from herbivore‐damaged soybean plants on searching behavior of the egg parasitoid Telenomus podisi

Parasitoids use herbivore‐induced plant volatiles (HIPVs) to locate their hosts. However, there are few studies in soybean showing the mechanisms involved in the attraction of natural enemies to their hosts and prey. The objective of this study was to evaluate the influence of volatile organic compounds (VOCs) of soybean, Glycine max (L.) Merr. (Fabaceae) (cv. Dowling), that were induced after injury caused by Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), on the searching behavior of the egg parasitoid Telenomus podisi Ashmead (Hymenoptera: Scelionidae). Four HIPVs from soybean, (E,E)‐α‐farnesene, methyl salicylate, (Z)‐3‐hexenyl acetate, and (E)‐2‐octen‐1‐ol, were selected, prepared from standards at various concentrations (10^?6 to 10^?1 m ), and tested individually and in combinations using a two‐choice olfactometer (type Y). Telenomus podisi displayed a preference only for (E,E)‐α‐farnesene at 10^?5 m when tested individually and compared to hexane, but they did not respond to the other compounds tested individually at any concentration or when combinations of these compounds were tested. However, the parasitoids stayed longer in the olfactometer arm with the mixture of (E,E)‐α‐farnesene + methyl salicylate at 10^?5 m than in the arm containing hexane. The results suggest that (E,E)‐α‐farnesene and methyl salicylate might help T. podisi to determine the presence of stink bugs on a plant. In addition, bioassays were conducted to compare (E,E)‐α‐farnesene vs. the volatiles emitted by undamaged and E. heros‐damaged plants, to evaluate whether (E,E)‐α‐farnesene was the main cue used by T. podisi or whether other minor compounds from the plants and/or the background might also be used to locate its host. The results suggest that minor volatile compounds from soybean plants or from its surroundings are involved in the host‐searching behavior of T. podisi.     

Hydrolytic resolution of (R,S)-2-hydroxycarboxylic acid esters in biphasic media: implication for rate-limiting formation or breakdown of tetrahedral intermediates in acylation step

A thermally stable esterase (SNSM‐87) from Klebsiella oxytoca is explored as an enantioselective biocatalyst for the hydrolytic resolution of (R,S)‐2‐hydroxycarboxylic acid esters in biphasic media, where the best methyl esters possessing the highest enantioselectivity and reactivity are selected and elucidated in terms of the structure–enantioselectivity correlations and substrate partitioning in the aqueous phase. With (R,S)‐2‐chloromandelates as the model substrates, an expanded Michaelis–Menten mechanism for the rate‐limiting acylation step is adopted for the kinetic analysis. The Brønsted slope of 25.7 for the fast‐reacting (S)‐2‐chloromandelates containing a difficult leaving alcohol moiety, as well as that of 4.13 for the slow‐reacting (R)‐2‐chloromandelates in the whole range of leaving alcohol moieties, indicates that the breakdown of tetrahedral intermediates to acyl‐enzyme intermediates is rate‐limiting. However, the rate‐limiting step shifts to the formation of tetrahedral intermediates for the (S)‐2‐chloromandelates containing an easy leaving alcohol moiety, and leads to an optimal enantioselectivity for the methyl ester substrate. Biotechnol. Bioeng. 2007; 98: 30–38. © 2007 Wiley Periodicals, Inc.     

Benzopyran Derivatives and an Aliphatic Compound from a Mangrove Endophytic Fungus Penicillium citrinum QJF‐22

Two new benzopyran derivatives, (2R,4S)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol and (2S,4R,2′S,4′R)‐4,4′‐oxybis(5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran), and a new aliphatic compound, (3E,5Z,8S,10E)‐8‐hydroxytrideca‐3,5,10,12‐tetraen‐2‐one, together with three known benzopyran derivatives, were obtained from a mangrove endophytic fungus Penicillium citrinum QJF‐22 collected in Hainan island. Their structures were determined by analysis of spectroscopic data and the relative configuration of (2R,4S)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol was also confirmed by single‐crystal X‐ray diffraction. The absolute configurations of four compounds were established by comparison of ECD spectra to calculations. The configuration of (3E,5Z,8S,10E)‐8‐hydroxytrideca‐3,5,10,12‐tetraen‐2‐one was confirmed by comparison of optical value to the similar compound. The configurations of the compounds (2S,4S)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol and (2R,4R)‐5‐methoxy‐2‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐4‐ol were first determined. (3R,4S)‐3,4,8‐Trihydroxy‐3,4‐dihydronaphthalen‐1(2H)‐one exhibited moderate inhibitory effects on LPS‐induced NO production in RAW264.7 cells with IC₅₀ of 44.7 μM, and without cytotoxicity to RAW264.7 cells within 50 μM.     

Chiral syntheses of methyl (R)‐2‐Sulfanylcarboxylic esters and acids with optical purity determination using HPLC

Accessible chiral syntheses of 3 types of (R)‐2‐sulfanylcarboxylic esters and acids were performed: (R)‐2‐sulfanylpropanoic (thiolactic) ester (53%, 98%ee) and acid (39%, 96%ee), (R)‐2‐sulfanylsucciinic diester (59%, 96%ee), and (R)‐2‐mandelic ester (78%, 90%ee) and acid (59%, 96%ee). The present practical and robust method involves (i) clean S_N2 displacement of methanesulfonates of (S)‐2‐hydroxyesters by using commercially available AcSK with tris(2‐[2‐methoxyethoxy])ethylamine and (ii) sufficiently mild deacetylation. The optical purity was determined by the corresponding (2R,5R)‐trans‐thiazolidin‐4‐one and (2S,5R)‐cis‐thiazolidin‐4‐one derivatives based on accurate high‐performance liquid chromatography analysis with high‐resolution efficiency. Compared with the reported method utilizing AcSCs (generated from AcSH and CsCO₃), the present method has several advantages, that is, the use of odorless AcCOSK reagent, reasonable reaction velocity, isolation procedure, and accurate, reliable optical purity determination. The use of accessible AcSK has advantages because of easy‐to‐handle odorless and hygroscopic solid that can be used in a bench‐top procedure. The Ti(OiPr)₄ catalyst promoted smooth trans‐cyclo‐condensation to afford (2R,5R)‐trans‐thiazolidin‐4‐one formation of (R)‐2‐sulfanylcarboxylic esters with available N‐(benzylidene)methylamine under neutral conditions without any racemization, whereas (2S,5R)‐cis‐thiazollidin‐4‐ones were obtained via cis‐cyclo‐condensation and no catalysts. Direct high‐performance liquid chromatography analysis of methyl (R)‐mandelate was also performed; however, the resolution efficiency was inferior to that of the thaizolidin‐4‐one derivatizations.     

Two New Antioxidant Phenylpropanoids from Lindelofia stylosa

Two new phenylpropanoids were isolated from Lindelofia stylosa (Kar . and Kir .) and characterized as 4‐hydroxy‐N‐{4‐[(E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enamido]butyl}benzamide ( 1 ) and 2‐[3‐hydroxy‐4‐(4‐hydroxyphenoxy)phenyl]‐1‐(methoxycarbonyl)ethyl (E)‐3‐(3,4‐dihydroxyphenyl)prop‐2‐enoate ( 2 ). Four known compounds, i.e. two phenylpropanoids, p‐coumaric acid (=(E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoic acid; 3 ) and ferulic acid (=(E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoic acid; 4 ), and two naphthalene glycosides, 8‐O‐β‐D ‐glucopyranosyltorachrysone ( 5 ) and 8‐O‐β‐D ‐glucopyranosyl‐6‐demethoxytorachrysone ( 6 ), were also isolated for the first time from the plant. Compounds 1 – 6 were subjected to various antioxidant assays, including DPPH radical‐ and superoxide anion‐scavenging, and Fe²⁺‐chelation assays. Compound 2 was found to be most active in all assays with potency nearly similar to that of propyl gallate. Besides 2 , compounds 1 and 5 were also found to be active in DPPH radical‐scavenging standard assay.     

Synthesis and binding potencies of cyclohexapeptide somatostatin analogs containing naphthylalanine and arylalkyl peptoid residues

We report the synthesis, binding affinities to the recombinant human somatostatin receptors, and structure‐activity relationship studies of compounds related to the cyclic hexapeptide, c‐[Pro⁶‐Phe⁷‐D‐Trp⁸‐Lys⁹‐Thr¹⁰‐Phe¹¹], L‐363,301 (the numbering in the sequence refers to the position of the residues in native somatostatin). The Pro residue in this compound is replaced with the arylalkyl peptoid residues Nphe (N‐benzylglycine), (S)βMeNphe [(S)‐N‐[(α‐methyl)benzyl]glycine] or (R)βMeNphe [(R)‐N‐[(α‐methyl)benzyl]glycine] and l ‐1‐naphthylalanine is incorporated into either position 7 or 11 of the parent compound. The synthesis and binding data of the Nnal⁶ ([N‐naphthylmethyl]glycine) analog of L‐363,301 is also reported. The incorporation of the Nnal residue into position 6 of L‐363,301 resulted in an analog with weaker binding affinities to all hsst receptors but enhanced selectivity towards the hsst2 receptor compared with the parent compound. The other compounds bind effectively to the hsst2 receptor but show some variations in the binding to the hsst3 and hsst5 receptors resulting in different ratios of binding affinities to the hsst5 and hsst2 or hsst3 and hsst2, respectively. The incorporation of the Nphe residue into position 6 and the Nal residue into position 7 of L‐363,301 led to a compound which binds potently to the hsst2 and has increased selectivity towards this receptor (weaker binding to hsst3 and hsst5 receptors) compared with the parent compound. The analogs with β‐methyl chiral substitutions in the aromatic peptoid side chain and Nal in position 7 or 11 bind effectively to the hsst2 and hsst5 receptors. They exhibit similar ratios of binding affinities to the hsst5 and hsst2 receptors as observed for L‐363,301. There are however minor differences in binding to the hsst3 receptor among these analogs. These studies allow us to investigate the influence of additional hydrophobic groups on the binding activity to the isolated human somatostatin receptors and the results are important for the design of other somatostatin analogs. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd.     

Vanadium-catalyzed transformation of 13(S)-hydroperoxy-9(Z), 11(E)-octadecadienoic acid: Structural studies on epoxy alcohols and trihydroxy acids

Treatment of methyl 13(S)-hydroperoxy-9(Z), 11(E)-octadecadienoate with vanadium oxyacetylacetonate led to the formation of two diastereometric α,β-epoxy alcohols, i.e. methyl 11(R), 12(R)-epoxy-13(S)-hydroxy-9(Z)-octadecenoate and methyl 11(S), 12(S)-epoxy-13(S)-hydroxy-9(Z)-octadecenoate. The epoxy alcohols underwent spontaneous hydrolysis into isomeric trihydroxyesters. The first mentioned epoxy alcohol afforded methyl 9(R), 12(S), 13(S)- and methyl 9(S), 12(S), 13(S)-trihydroxy-10(E)-octadecenoates as major hydrolysis products whereas the latter epoxy alcohol afforded methyl 9(R), 12(R), 13(S)- and methyl 9(S), 12(R)-13(S)-trihydroxy-10(E)-octadecenoates as major compounds. Smaller amounts of diastereomeric methyl 11,12,13-trihydroxy-9-octadecenoates were also formed from both epoxy alcohols. The vanadium-catalyzed conversion of 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoic acid (13(S)HPOD) (methyl ester) into α,β-epoxy alcohols and their further conversion into trihydroxy derivatives offers a model system for similar transformations of certain poly-unsaturated fatty acids recently described in the fungus, Saprolegnia parasitica.     

Antiproliferative Evaluation of Some 2‐[2‐(2‐Phenylethenyl)‐cyclopent‐3‐en‐1‐yl]‐1,3‐benzothiazoles: DFT and Molecular Docking Study

The 2‐[2‐(2‐phenylethenyl)cyclopent‐3‐en‐1‐yl]‐1,3‐benzothiazoles were synthesized from the reactions of 7‐benzylidenebicyclo[3.2.0]hept‐2‐en‐6‐ones with 2‐aminobenzenethiol. The antiproliferative activities of 2‐[2‐(2‐phenylethenyl)cyclopent‐3‐en‐1‐yl]‐1,3‐benzothiazoles were determined against C6 (rat brain tumor) and HeLa (human cervical carcinoma cells) cell lines using BrdU cell proliferation ELISA assay. Cisplatin and 5‐fluorouracil (5‐FU) were used as standards. The most active compound was 2‐{(1S,2S)‐2‐[(E)‐2‐(4‐methylphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against C6 cell lines with IC₅₀=5.89 μm value (cisplatin, IC₅₀=14.46 μm and 5‐FU, IC₅₀=76.74 μm ). Furthermore, the most active compound was 2‐{(1S,2S)‐2‐[(E)‐2‐(2‐methoxyphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against HeLa cell lines with IC₅₀=3.98 μm (cisplatin, IC₅₀=37.95 μm and 5‐FU, IC₅₀=46.32 μm ). Additionally, computational studies of related molecules were performed by using B3LYP/6‐31G+(d,p) level in the gas phase. Experimental IR and NMR data were compared with the calculated results and were found to be compatible with each other. Molecular electrostatic potential (MEP) maps of the most active 2‐{(1S,2S)‐2‐[(E)‐2‐(2‐methoxyphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against HeLa and the most active 2‐{(1S,2S)‐2‐[(E)‐2‐(4‐methylphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against C6 were investigated, aiming to determine the region that the molecule is biologically active. Biological activities of mentioned molecules were investigated with molecular docking analyses. The appropriate target protein (PDB codes: 1 M17 for the HeLa cells and 1JQH for the C6 cells) was used for 2‐{(1S,2S)‐2‐[(E)‐2‐(2‐methoxyphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole and 2‐{(1S,2S)‐2‐[(E)‐2‐(4‐methylphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole molecules exhibiting the highest biological activity against HeLa and C6 cells in the docking studies. As a result, it was determined that these molecules are the best candidates for the anticancer drug.     

Mitsunobu Alkylation of Cancerostatic 5‐Fluorouridine with (2E)‐10‐Hydroxydec‐2‐enoic Acid,a Fatty Acid from Royal Jelly with Multiple Biological Activities

5‐Fluorouridine ( 1 ) – a nucleoside antimetabolite with strong cancerostatic properties – was protected i) at the 2′‐ and 3′‐OH groups with a heptan‐4‐ylidene residue and ii) at the 5′‐OH group with a (4‐methoxyphenyl)(diphenyl)methyl residue. This fully protected compound, 3 , was submitted to a Mitsunobu reaction with the N‐hydroxysuccinimide (NHS) ester, 5 , of (2E)‐10‐hydroxydec‐2‐enoic acid ( 4 ) which gave nucleolipid 6 . The latter was detritylated with Cl₂CHCOOH to yield the co‐drug 7 as NHS ester.     

Synergism between aromatic compounds and green leaf volatiles derived from the host plant underlies female attraction in the oriental fruit moth

Blends of volatile compounds emitted by host plants are known to mediate the attraction of gravid female herbivores to oviposition sites, but the role of individual odor components is still little understood. We characterized the olfactory response of mated female Cydia (Grapholita) molesta (Busck) (Lepidoptera: Tortricidae) to synthetic mixtures of compounds emitted by peach shoot, a key host plant of this herbivore, and investigated the role of important constituents of bioactive mixtures in moth attraction. Relative ratios of constituents of the mixtures corresponded to the natural ratio of volatile compounds collected in the plant's headspace. A significant attractant effect was found for a comparatively complex 10‐compound mixture that included four green leaf volatiles [(Z)‐3‐hexen‐1‐ol, 1‐hexanol, (E)‐2‐hexenal, and (Z)‐3‐hexen‐1‐yl acetate], five aromatics (benzaldehyde, methyl salicylate, methyl benzoate, benzonitrile, and phenylacetonitrile), and a carboxylic acid (valeric acid). Using a subtraction approach, the number of compounds was progressively decreased, resulting in a bioactive 5‐compound mixture composed of two constituents, green leaf volatiles and aromatic compounds. Further evaluations revealed that benzaldehyde and benzonitrile must be present in association with three distinct green leaf volatiles to produce an attractant effect on the female moths. This 5‐compound mixture was as attractive as natural peach shoot volatiles, which are known to comprise over 20 compounds. Results are discussed in light of the documented synergistic effect between the three general green leaf volatiles and the two specific aromatic compounds.     

Expression of lima bean terpene synthases in rice enhances recruitment of a beneficial enemy of a major rice pest

Volatile terpenoids play a key role in plant defence against herbivory by attracting parasitic wasps. We identified seven terpene synthase genes from lima bean, Phaseolus lunatus L. following treatment with either the elicitor alamethicin or spider mites, Tetranychus cinnabarinus. Four of the genes (Pltps2, Pltps3, Pltps4 and Pltps5) were up‐regulated with their derived proteins phylogenetically clustered in the TPS‐g subfamily and PlTPS3 positioned at the base of this cluster. Recombinant PlTPS3 was able to convert geranyl diphosphate and farnesyl diphosphate to linalool and (E)‐nerolidol, the latter being precursor of the homoterpene (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT). Recombinant PlTPS4 showed a different substrate specificity and produced linalool and (E)‐nerolidol, as well as (E,E)‐geranyllinalool from geranylgeranyl diphosphate. Transgenic rice expressing Pltps3 emitted significantly more (S)‐linalool and DMNT than wild‐type plants, whereas transgenic rice expressing Pltps4 produced (S)‐linalool, DMNT and (E,E)‐4,8,12‐trimethyl‐1,3,7,11‐tridecatetraene (TMTT). In laboratory bioassays, female Cotesia chilonis, the natural enemy of the striped rice stemborer, Chilo suppressalis, were significantly attracted to the transgenic plants and their volatiles. We further confirmed this with synthetic blends mimicking natural rice volatile composition. Our study demonstrates that the transformation of rice to produce volatile terpenoids has the potential to enhance plant indirect defence through natural enemy recruitment.     

Predator–prey interactions: olfactory adaptations of generalist and specialist predators

1 Olfactory responses of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), a generalist predator, Podisus maculiventris (Say) (Hemiptera, Heteroptera: Pentatomidae) (Pm), and a specialist predator, Perillus bioculatus (F.) (Hemiptera, Heteroptera: Pentatomidae) (Pb) were investigated. Volatiles tested included 20 compounds emitted by undamaged potato plants (Solanum tuberosum), plants that had been artificially damaged, or plants damaged by feeding by CPB larvae. 2 Coupled gas chromatography/electroantennogram detector (GC/EAD) recordings revealed five compounds for which reliable responses were recorded from CPB antennae: (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, (±)-linalool, nonanal, methyl salicylate, and indole. Both Pm and Pb responded selectively to the same compounds as the CPB with exceptions: (1) (Z)-3-hexenyl butyrate elicited reliable responses for both Pm and Pb, and (2) (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol were inactive for Pm and Pb under these conditions. Dose–response curves showed that CPB was at least 100 times more sensitive to (E)-2-hexen-1-ol than were the predators. Both predators were more sensitive to each of the other compounds than were CPB. Both CPB and Pm were attracted to a five component blend comprising (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, (±)-linalool, nonanal and methyl salicylate. However, attraction of CPB to the blend occurred only with lower doses of (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol. 3 These results show that the herbivore (CPB) has olfactory receptors which are more sensitive to constitutive host plant volatiles, e.g. green leaf volatiles, while both generalist (Pm) and specialist (Pb) predators are more sensitive to systemic volatiles produced in response to prey feeding. Keywords Colorado potato beetle, constitutive compounds, host plant, induced compounds, olfaction, Perillus bioculatus, Podisus maculiventris, predator, prey, tritrophic.     

Stereoselective Binding of Flurbiprofen Enantiomers and their Methyl Esters to Human Serum Albumin Studied by Time-Resolved Phosphorescence

The interaction of the nonsteroidal anti‐inflammatory drug flurbiprofen (FBP) with human serum albumin (HSA) hardly influences the fluorescence of the protein's single tryptophan (Trp). Therefore, in addition to fluorescence, heavy atom‐induced room‐temperature phosphorescence is used to study the stereoselective binding of FBP enantiomers and their methyl esters to HSA. Maximal HSA phosphorescence intensities were obtained at a KI concentration of 0.2 M. The quenching of the Trp phosphorescence by FBP is mainly dynamic and based on Dexter energy transfer. The Stern–Volmer plots based on the phosphorescence lifetimes indicate that (R)‐FBP causes a stronger Trp quenching than (S)‐FBP. For the methyl esters of FBP, the opposite is observed: (S)‐(FBPMe) quenches more than (R)‐FBPMe. The Stern–Volmer plots of (R)‐FBP and (R)‐FBPMe are similar although their high‐affinity binding sites are different. The methylation of (S)‐FBP causes a large change in its effect on the HSA phosphorescence lifetime. Furthermore, the quenching constants of 3.0 × 10⁷ M^?1 s^?1 of the R‐enantiomers and 2.5 × 10⁷ M^?1 s^?1 for the S‐enantiomers are not influenced by the methylation and indicate a stereoselectivity in the accessibility of the HSA Trp to these drugs. Chirality 24:840–846, 2012. © 2012 Wiley Periodicals, Inc.     

Application of NMR spectroscopy for assignment of the absolute configuration of 8‐tert‐butyl‐2‐hydroxy‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]dec‐6‐en‐10‐one

In order to assign the absolute configurations of 8‐tert‐butyl‐2‐hydroxy‐7‐methoxy‐8‐methyl‐9‐oxa‐6‐azaspiro[4.5]dec‐6‐en‐10‐one ( 2a , 2b ), their esters ( 5a , 5b , 5c , 5d ) with (R)‐ or (S)‐2‐methoxyphenylacetic acid ( 4a , 4b ) have been synthesized. The absolute configurations of these compounds have been determined on the basis of NOESY correlations between the protons of the tert‐butyl group and the cyclopentane fragment of the molecules. The crucial part of this analysis was assignment of the absolute configuration at C‐5. Additionally, by calculation of the chemical shift anisotropy, δ^RS, for the relevant protons, it was also possible to confirm the absolute configurations at the C‐2 centres of compounds 2a , 2b and 5a , 5b , 5c , 5d . Chirality, 25:422–426, 2013.© 2013 Wiley Periodicals, Inc.     

Electrophysiological and behavioural responses of Melolontha melolontha to saturated and unsaturated aliphatic alcohols

Male Melolontha cockchafers are known to use green leaf volatiles induced by female feeding on host plants for their mate location. Earlier studies of the response of the European cockchafer, Melolontha melolontha L. (Coleoptera: Scarabaeidae), to different green leaf aldehydes, alcohols, and acetates revealed that only green leaf alcohols were attractive to males in the field. Females were not attracted at all by these volatiles. Here, we present a study that aimed to elucidate the structure–activity relationships of aliphatic alcohols. Both behavioural and physiological responses were studied in male and female M. melolontha by field tests and electroantennography. The compounds tested were saturated aliphatic alcohols with chain lengths between five and eight carbon atoms. Furthermore, the cockchafer's response to six‐carbon alcohols with (E)‐2‐, (E)‐3‐, (Z)‐2‐, (Z)‐3‐, and (Z)‐4‐configurated double bonds was tested. All compounds elicited dose‐dependent responses on the antennae of both sexes. In general, males showed a stronger normalized EAG response to the stimuli than females. However, only the naturally occurring six‐carbon alcohols, i.e., 1‐hexanol (E)‐2‐, (Z)‐3, and (E)‐3‐hexen‐1‐ol were attractive to M. melolontha males in the field. Females were not attracted to any of the tested compounds, confirming previous results on the olfactory orientation of Melolontha cockchafers.     

An Approach to the Chemotaxonomic Differentiation of Two European Dog's Mercury Species: Mercurialis annua L. and M. perennis L.

Mercurialis annua and M. perennis are medicinal plants used in complementary medicine. In the present work, analytical methods to allow a chemotaxonomic differentiation of M. annua and M. perennis by means of chemical marker compounds were established. In addition to previously published compounds, the exclusive presence of pyridine‐3‐carbonitrile and nicotinamide in CH₂Cl₂ extracts obtained from the herbal parts of M. annua was demonstrated by GC/MS. Notably, pyridine‐3‐carbonitrile was identified for the first time as a natural product. Further chromatographic separation of the CH₂Cl₂ extracts via polyamide yielded a MeOH fraction exhibiting a broad spectrum of side‐chain saturated n‐alkylresorcinols. While the n‐alkylresorcinol pattern was similar for both plant species, some specific differences were observed for particular n‐alkylresorcinol homologs. Finally, the investigation of H₂O extracts by LC/MS/MS revealed the presence of depside constituents. Whereas, in M. perennis, a mixture of mercurialis acid (=(2R)‐[(E)‐caffeoyl]‐2‐oxoglutarate) and phaselic acid (=(E)‐caffeoyl‐2‐malate) could be detected, in M. annua solely phaselic acid was found. By comparison with synthesized enantiomerically pure (2R)‐ and (2S)‐phaselic acids, the configuration of the depside could be determined as (2S) in M. annua and as (2R) in M. perennis.     

Identification of host‐plant chemical stimuli for the European grape berry moth Eupoecilia ambiguella

Olfaction is of major importance for survival and reproduction in moths. Males possess highly specific and sensitive olfactory receptor neurones to detect female sex pheromones. However, the capacity of male moths to respond to host‐plant volatiles is relatively neglected and the role that such responses could play in the sensory ecology of moths is still not fully understood. The present study aims to identify host‐plant stimuli for the European grape berry moth Eupoecilia ambiguella Hb. (Tortricidae, Lepidoptera), a major pest of vine in Europe. Headspace volatiles from Vitis vinifera L. cv. Pinot Noir, Vitis vinifera subsp. sylvestris and five other host‐plant species comprising five different families are analyzed by gas chromatography linked to electroantennogram (EAG) recording from male E. ambiguella antennae and by gas chromatography‐mass spectrometry. This procedure identifies 32 EAG‐active compounds, among them the aliphatic compounds 1‐hexanol, (Z)‐3‐hexenol, (Z)‐3‐hexenyl acetate and 1‐octen‐3‐ol; the terpenes limonene, β‐caryophyllene and (E)‐4,8‐dimethyl‐1,3,7‐nonatriene; and the aromatic compounds benzaldehyde and methyl salicylate. Male and female E. ambiguella show similar EAG response amplitudes to individual chemical stimuli and also to mixtures of plant volatiles, as represented by essential oils from ten other plant species. This possibly indicates a common role for plant compounds in the sensory ecology of the two sexes of E. ambiguella.     

Terpenoids from Rhizomes of Alpinia japonica Inhibiting Nitric Oxide Production

A new sesquiterpenoid, 1 , and three new diterpenoids, 3 – 5 , along with five known compounds, 2 and 6 – 9 , were isolated from rhizomes of Alpinia japonica. The structures of the new compounds were determined as (1R,4R,6S,7S,9S)‐4α‐hydroxy‐1,9‐peroxybisabola‐2,10‐diene ( 1 ), methyl (12E)‐16‐oxolabda‐8(17),12‐dien‐15‐oate ( 3 ), (12R)‐15‐ethoxy‐12‐hydroxylabda‐8(17),13(14)‐dien‐16,15‐olide ( 4 ), and methyl (11E)‐14,15,16‐trinorlabda‐8(17),11‐dien‐13‐oate ( 5 ) by means of spectroscopic data. The absolute configurations at C(4) in 1 and C(12) in 4 were deduced from the circular dichroism (CD) data of the in situ‐formed [Rh₂(CF₃COO)₄] complexes. Inhibitory effects of the isolates on NO production in lipopolysaccharide‐induced RAW264.7 macrophages were evaluated, and 2 – 4, 6 , and 7 were found to exhibit inhibitory activities with IC₅₀ values between 14.6 and 34.3 μM .     

Enantiomers of fuscumol acetate comprise the aggregation‐sex pheromone of the South American cerambycid beetle Psapharochrus maculatissimus,and likely pheromones of the cerambycids Eupromerella plaumanni and Hylettus seniculus

There is increasing evidence that pheromone chemistry within the large coleopteran family Cerambycidae is often highly conserved, with numerous related species sharing the same pheromone components. As a result, traps containing these components can attract multiple cerambycid species simultaneously. In the present study, we exploited this concept in the identification of the male‐produced aggregation‐sex pheromone of the South American species Psapharochrus maculatissimus (Bates) (Coleoptera: Cerambycidae, subfamily Lamiinae, tribe Acanthoderini). Initially, live adults of both sexes were caught using a trap baited with a lure containing a blend of known cerambycid pheromone components. Headspace volatiles were collected from live beetles and analyzed by coupled gas chromatography‐mass spectrometry. Males of P. maculatissimus sex‐specifically produced a 1:38 blend of (R)‐fuscumol acetate ([2R,5E]‐6,10‐dimethylundeca‐5,9‐dien‐2‐yl acetate) and (S)‐fuscumol acetate, which were both components of the pheromone lures to which they had been attracted. In more focused field trials, traps baited with the (S)‐enantiomer, or a blend approximating the natural 1:38 ratio of (R)‐ to (S)‐enantiomers, attracted adults of both sexes in approximately equal numbers. During bioassays, adults of the lamiine species Eupromerella plaumanni (Fuchs) (tribe Acanthoderini) and Hylettus seniculus (Germar) (Acanthocinini) also were attracted, but to different lures, with E. plaumanni being attracted to the racemic mixture of the two enantiomers of fuscumol acetate, whereas H. seniculus was attracted specifically to (R)‐fuscumol acetate. Our results suggest that differences between these sympatric species in the stereochemistry of fuscumol acetate impart species‐specificity to pheromone communication channels, similar to what has been found recently with lamiine species from other continents.