Essential oil composition of Piper guineense and its antimicrobial activity. Another chemotype from Nigeria.

The analysis of the essential oil of Piper guineense from Nigeria presents a new chemotype of constituents different from earlier reports with the absence of the usual myristicin. Ishwarane, a common constituent of Aristolochia indica and Bixa orellana, was also isolated from the essential oil of the fruit. The essential oil inhibited the growth of Pseudomonas aeruginosa UCH 655 strain at 5 mg/mL on which standard antibiotic drugs were ineffective.

(-)-Germacrene D receptor neurones in three species of heliothine moths: structure-activity relationships.

Specificity of olfactory receptor neurones plays an important role in food and host preferences of a species, and may have become conserved or changed in the evolution of polyphagy and oligophagy. We have identified a major type of plant odour receptor neurones responding to the sesquiterpene germacrene D in three species of heliothine moths, the polyphagous Heliothis virescens and Helicoverpa armigera and the oligophagous Helicoverpa assulta. The neurones respond with high sensitivity and selectivity to (-)-germacrene D, as demonstrated by screening via gas chromatography with numerous mixtures of plant volatiles. Germacrene D was present in both host and non-host plants, but only in half of the tested species. The specificity of the neurones was similar in the three species, as shown by the "secondary" responses to a few other sesquiterpenes. The effect of (-)-germacrene D was about ten times stronger than that of the (+)-enantiomer, which again was about ten times stronger than that of (-)-alpha-ylangene. Weaker effects were obtained for (+)-beta-ylangene, (+)-alpha-copaene, beta-copaene and two unidentified sesquiterpenes. The structure-activity relationship shows that the important properties of (-)-germacrene D in activating the neurones are the ten-membered ring system and the three double bonds acting as electron-rich centres, in addition to the direction of the isopropyl-group responsible for the different effects of the germacrene D enantiomers.

Synthetic musks in the environment. Part 2: Enantioselective transformation of the polycyclic musk fragrances HHCB, AHTN, AHDI, and ATII in freshwater fish.

A method for the enantioselective separation of the chiral polycyclic musks HHCB, AHTN, AHDI, and ATII is presented. Eighteen fish samples (rudd, tench, crucian carp, eel) and one pooled zebra mussel sample from the pond of a municipal sewage treatment plant were investigated with regard to their concentrations and the enantiomeric ratios (ERs) of polycyclic musks. In addition, three water samples taken at the effluent of the sewage plant, as well as two water samples and two series of semipermeable membrane devices (SPMDs) consisting of six samples each from the pond were included in the present study. This comprehensive data set allowed a reliable evaluation of species-dependent metabolization processes. The pattern of the polycyclic musks in the chromatograms obtained by enantioselective gas chromatography seems to be typical of each species, like a fingerprint. The highest deviations from the racemic ER were found for trans-HHCB and trans-ATII in crucian carp with values of or below 0.1. Calculations showed that enantioselective transformation seems to be the most important process, resulting in the observed lower concentrations in crucian carp compared to tench. Consequences for a risk assessment are discussed.

Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n-diaza[n]paracyclophanes using cyclodextrin-mediated capillary zone electrophoresis.

A number of variously monosubstituted 1,n-diaza[n]paracyclophanes (n = 10-12), which show planar chirality and atropisomerism due to hindered rotation about single bonds, were synthesized via a classical route to analyze their stereodynamic properties. Racemic analytes with 10- and 11-membered bridges were resolved by capillary zone electrophoresis (CZE) in acidic phosphate buffers (pH 2.5-4.5) employing permethylated beta- and gamma-cyclodextrin as chiral additives. Moreover, cyclodextrin mediated CZE was used in a discontinuously driven mode for investigations of the rotational interconversion process of conformationally labile homologues (n = 11). In stopped-flow experiments, after baseline separation enantiomers were partially enantiomerized in situ inside the capillary by heating. The rate constants (k(enan) = 1/2 k(rac)) and rotational energy barriers (Delta G(++)) were determined from the resulting enantiomeric ratios. Energy barriers between 113-126 kJ/mol were found depending on the substituent of the benzene ring and the degree of ionization of the amino groups in bridgehead positions. The energy barriers increased in order of the substituents: NO(2) >> CF(3) > Br > Cl > CH(3) approximately F. In addition, the rotational energy barriers were decreased by approximately 6-8 kJ/mol in the presence of the chiral selector.

Scyptolin A and B, cyclic depsipeptides from axenic cultures of Scytonema hofmanni PCC 7110.

Two novel cyclic depsipeptides were isolated from axenic cultures of the terrestrial cyanobacterium Scytonema hofmanni PCC 7110 and designated scyptolin A and B. Amino acid analyses in context with mass and 1H/13C NMR spectroscopies revealed a composition typical for heterologous cyanopeptolins but containing the uncommon residue 3'-chloro-N-methyl-Tyr (cmTyr) and a unique sidechain. Scyptolin A and B both consist of the N-acylated peptide But(1)-Ala(2)-Thr(3)-Thr(4)-Leu(5)-Ahp(6) (3-amino-6-hydroxy-2-oxo-1-piperidine)-Thr(7)-cmTyr(8)-Val(9), which forms a 19-membered ring by esterification of the carboxyl of Val(9) with the hydroxyl of Thr(4). In scyptolin B, the hydroxyl of the Thr(3) residue is additionally esterified with N-butyroyl-Ala. Both scyptolin A and B exhibit selective inhibition of porcine pancreatic elastase in vitro with IC(50) values of 3.1 microg/ml.

Synthesis and stereochemistry of some bicyclic gamma-lactones from parasitic wasps (Hymenoptera: Braconidae). Utility of hydrolytic kinetic resolution of epoxides and palladium(II)-catalyzed hydroxycyclization-carbonylation-lactonization of ene-diols.

A palladium(II)-catalyzed hydroxycyclization-carbonylation-lactonization sequence with appropriate pent-4-ene-1,3-diols provides efficient access to the bicyclic gamma-lactones, 5-n-butyl- and 5-n-hexyltetrahydrofuro-[3,2-b]furan-2(3H)-ones (3) and (4), respectively, in both racemic and enantiomeric forms. Some of the substrate pent-4-ene-1,3-diols of high enantiomeric excess (ee) have been derived from racemic terminal epoxides by hydrolytic kinetic resolution (HKR) using cobalt (III)-salen complexes. (9Z,12R)-(+)-Ricinoleic acid also serves as a "chiral pool" source of other pent-4-ene-1,3-diols. These syntheses and enantioselective gas chromatography confirm the structures and absolute stereochemistry of the lactones in some species of parasitic wasps (Hymenoptera: Braconidae). The highly abundant 5-n-hexyltetrahydrofuro-[3,2-b]furan-2(3H)-one (4) in Diachasmimorpha kraussii and D. longicaudata is of high ee (>99%) with (3aR,5R,6aR) stereochemistry.

Sesquiterpenoid constituents of the liverworts Lepidozia fauriana and Lepidozia vitrea.

The sesquiterpene constituents of the essential oils of the Taiwanese liverworts Lepidozia fauriana and L. vitrea were investigated. 11,12-Dihydrochiloscyphone and 7,10-anhydro-11,12-dihydrochiloscypholone were isolated from L. fauriana and spectroscopically characterised together with their hydrogenation products. From the same species three amorphane derivatives amorpha-4,9-dien-14-al, amorpha-4,9-dien-2-ol and 7,14-anhydroamorpha-4,9-diene, and from L. vitrea two oxygenated elemanes, namely 7-acetoxy-elema-1,3-dien-8-ol and elema-1,3-dien-7-ol, were isolated and identified. Structure elucidation was carried out by NMR spectroscopy and chemical correlations in conjunction with enantioselective gas chromatography were utilized to establish absolute configurations.

Chemical study of the essential oil of Cyperus rotundus.

Minor constituents of the essential oil of Cyperus rotundus have been investigated. The three new sesquiterpene hydrocarbons (-)-isorotundene, (-)-cypera-2,4(15)-diene, (-)-norrotundene and the ketone (+)-cyperadione were isolated and their structures elucidated. The absolute configuration of (-)-rotundene was derived by chemical correlation and enantioselective gas chromatography.

Variable stereochemistry in highly branched isoprenoids from diatoms.

C(25) highly branched isoprenoid (HBI) alkenes are ubiquitous lipids found in geochemical samples around the globe. The origins of these widespread geochemicals are believed to be restricted to a limited number of diatoms, including Haslea ostrearia (and related species), Rhizosolenia setigera, and Pleurosigma intermedium. The unsaturation of the HBI alkenes ranges from 2-6 in different species and cultures. The number of stereogenic centres is usually limited to two in the HBI alkenes due to double bond positions. The relative and/or absolute configurations for these have been determined for a range of HBI alkenes produced from different diatoms cultured under a number of growth conditions. These determinations have involved a combined spectroscopic and chromatographic analysis using NMR spectroscopy and chiral gas chromatography, respectively. HBIs isolated from Haslea spp. belong to a specific structural type which exhibit configurational diastereoisomerism, while those isolated from P. intermedium and R. setigera represent a different structural type and usually exist as mixtures of geometric isomers only. HBIs are reported from a new species of diatom whose stereochemical properties lie between those found for Haslea spp. and P. intermedium.

Volatile constituents in mosses (Musci).

The essential oils of mosses of the genera Mnium, Plagiomnium, Homalia, Plagiothecium and Taxiphyllum (Musci) have been investigated by gas chromatography and mass spectrometry. The new sesquiterpenes (+)-10-epi-muurola-4,11-diene and 10,11-dihxdro-alpha-cuparenone were isolated by preparative gas chromatography and identified as major constituents of the hydrodistillation products of Mnium hornmum (Hedw.) using NMR and mass spectrometry. In addition, (+)-dauca-8,11-diene and two new butenolides, 3,4,5-trimethyl-5-pentyl-5H-furan-2-one and 3.4-dimethyl-5-pentyl-5H-furan-2-one were identified as constituents in Plagiomnium undulatum (Hedw.) T. Kop. Although the amounts of volatiles present in the investigated mosses are generally smaller than in liverworts, the spectrum of terpenoid compounds is similar. The investigated mosses also generate aliphatic compounds of greater abundance and structural variety.

Sesquiterpene hydrocarbons with trifarane backbone in the liverwort Trocholejeunea sandvicensis.

The hydrocarbon fraction of the liverwort Trocholejeunea sandvicensis was investigated. Four new sesquiterpene hydrocarbons including the trifaranes (-)-trifara-9,14-diene (6) and (-)-3,7-di-epi-3,7-trifara-9,14-diene (7), as well as (+)-sandvicene (8), a sesquiterpene with uncommon skeleton, and the rearranged trifarane sesquiterpene (+)-neotrifaradiene (9) were isolated and their structure elucidated. A biogenetic pathway for the four compounds is proposed, with nerolidol as their common precursor.

Pacifigorgianes and tamariscene as constituents of Frullania tamarisci and Valeriana officinalis.

The sesquiterpenoid constituents of the essential oils from the liverworts Frullania tamarisci, Frullania fragilifolia and of the angiosperm Valeriana officinalis were investigated. Tamariscene, a compound with a new sesquiterpene skeleton, valerena-4,7(11)-diene and five new pacifigorgiadienes, namely pacifigorgia-1,10-diene, pacifigorgia-1(6),10-diene, pacifigorgia-1(9),10-diene, pacifigorgia-2,10-diene, and pacifigorgia-2(10),11-diene were isolated and identified. Structure elucidation was carried out by NMR spectroscopy and chemical correlations to establish absolute configurations. Compounds present in both the essential oils of the Frullania species and Valeriana officinalis were enantiomeric to each other. A plausible biogenetic relationship between the pacifigorgiane, valerenane and tamariscane skeletons is postulated. Pacifigorgia-6,11-diene, not yet detected in nature, was generated by dehydration and rearrangement of natural (-)-tamariscol.

Constituents of the essential oil of Cyperus alopecuroides.

We have investigated the constituents of the essential oil of Cyperus alopecuroides. Three new compounds, the hydrocarbon, (-)-eudesma-2,4(15)-11-triene, the sesquiterpene alcohol (-)-eudesma-3,11-dien-5-ol and the diterpene hydrocarbon (-)-dolabella-3,7,18-triene were isolated and their structure elucidated.

The role of germacrene D as a precursor in sesquiterpene biosynthesis: investigations of acid catalyzed, photochemically and thermally induced rearrangements.

Germacrene D is considered as a precursor of many sesquiterpene hydrocarbons. We have investigated the acid catalyzed as well as the photochemically and thermally induced rearrangement processes of germacrene D isolated from several Solidago species, which contain both enantiomers of germacrene D. Enantiomeric mixtures of sesquiterpenes of the cadinane, eudesmane (selinane), oppositane, axane, isodaucane, and bourbonane group as well as isogermacrene D were identified as main products and made available as reference compounds for structure investigations and stereochemical assignments of plant constituents. Delta-amorphene, one of the rearrangement products, was identified as a natural product for the first time. The absolute configuration of gamma-amorphene was revised by correlation with the absolute configuration of germacrene D. The mechanisms of the rearrangement reactions are discussed.

Volatile constituents of wood-rotting basidiomycetes.

Phytochemical investigation of the hydrodistillation products of the basidiomycetes Fomitopsis pinicola, Piptoporus betulinus, Gloeophyllum odoratum and Trametes suaveolens led to the identification of numerous mono- and sesquiterpenes as well as many aliphatic alcohols, aldehydes and ketones and some aromatic compounds. In addition, some diterpenes were identified as constituents of Fomitopsis pinicola. The absolute configuration of some terpenes was determined

Constituents of the fungi Daedalea quercina and Daedaleopsis confragosa var. tricolor.

Phytochemical examination of solvent extracts of the wood-rotting fungi Daedalea quercina and Daedaleopsis confragosa var. tricolor led to the isolation of five new triterpene derivatives and some known fungal constituents. All structures were identified by one- and two-dimensional NMR spectroscopy and mass spectrometry. From Daedalea quercina, the new natural products 16-O-acetylpolyporenic acid C, 16alpha-acetoxy-24-methylene-3-oxolanost-8-en-21-oic acid, (+)-24-methylene-3,23-dioxolanost-8-en-26-oic acid, (+)-3beta,12beta-dihydroxy-24-methyl-23-oxolanost-8-en-26-oi c acid and 12beta,23-epoxy-3alpha,23-dihydroxy-24-methyllanost-8- en-26-oic acid could be isolated. From Daedaleopsis confragosa var. tricolor, the compounds 3alpha-carboxyacetoxyquercinic acid, 3alpha-carboxyacetoxy-24-methylene-23-oxolanost-8-en-2 6-oic acid and 5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol were identified. These are the first described triterpene derivatives isolated from this fungus.

Constituents of various wood-rotting basidiomycetes.

Phytochemical investigation of n-hexane and methanol extracts of fruiting bodies of the wood-rotting fungi Fomitopsis pinicola. Ganoderma lipsiense, Fomes fomentarius and Gloeophyllum odoratum led to the isolation and identification of several triterpene derivatives and some aromatic compounds derived from lignin. These are the new natural products, namely, pinicolic acid E (16alpha-hydroxy-3-oxolanosta-8,24-dien-21-oic acid) and pinicolol C (3-oxolanosta-7,9(11),24-trien-15alpha,21-diol) from the crust of F. pinicola, ganoderenic acid D [(E)-7beta-hydroxy-3,11,15,23-tetraoxolanosta-8,20(22)-di en-26-oic acid] and ganoderic acid N (7beta,20-dihydroxy-3,11,15,23-tetraoxolanost-8-en-26-oic acid) from G. lipsiense and ergosterol peroxide (5alpha,8alpha-epi-dioxyergost-6-en-3beta-ol) as well as ergost-7-en-3-one from F. fomentarius. From G. odoratum, dehydroeburicoic acid [24-methylene-3-oxolanosta-7,9(11)-dien-21-oic acid], the dimethylacetal of 4,4,14alpha-trimethyl-24-oxo-5alpha-chol-8-en-21-oic acid and some aromatic compounds, of which 1-(4'-methoxyphenyl)-1,2-ethandiol is a new natural product, were isolated. Furthermore, a complete set of 13C NMR data of the steryl esters 3beta-linoleyloxyergosta-7,24(28)-diene, 3beta-linoleyloxyergosta-7,24-diene and 3beta-linoleyloxyergost-7-ene, which could be identified as a mixture in all investigated fungi, could be recorded. It was proved by HPLC and TLC investigations, that the crust on top of the fruiting bodies of F. pinicola consists of lanostane derivatives.

Biosynthesis of the gymnomitrane-type sesquiterpenes in liverworts.

The biosynthesis of gymnomitranes in the liverworts Reboulia hemisphaerica (L.) Raddi and Bazzania trilobata (L.) Gray was investigated. Labelling experiments with 1-13C-, 2-13C- and 6,6-D2 glucose, 2,2-D2- and 4,4-D2 mevalolactone and tissue cultures of the liverworts were carried out.

Configurations of polyunsaturated sesterterpenoids from the diatom, Haslea ostrearia.

The partial configurations of C25 isoprenoid alkenes isolated from the diatom Haslea ostrearia Gaillon (Simonsen) have been established. A combination of NMR spectroscopy studies of the alkenes with chiral shift reagents in conjunction with soluble silver beta-diketonate complexes and enantioselective gas chromatography of oxidation products of the alkenes was used. Unexpected differences in highly branched isoprenoid isomer configurations were observed between different laboratory cultures of the alga.

Synthesis and silica-based immobilization of monofunctionalized cyclomaltoheptaose derivatives for enantioselective HPLC.

Heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)cyclomaltohep taose (6-TBDMS-2,3-Me-beta-CD) and heptakis(2,3,6-tri-O-methyl)cyclomaltoheptaose (per-Me-beta-CD) were monofunctionalized by introduction of a 5-cyanopentyl group attached to one of the O-2, O-3 or O-6 positions and subsequent reduction with lithium aluminum hydride to give the corresponding mono-O-(omega-aminohexyl) derivatives. Alternatively, after attachment of a 7-octenyl group and further epoxidation the corresponding mono-omega-epoxyoctyl derivatives of 6-TBDMS-2,3-Me-beta-CD were obtained. The mono-O-(omega-aminohexyl) derivatives were immobilized by reaction with glycidoxypropyl and 'aldehyde' silica, whereas aminopropyl silica was used for the immobilization of the monoepoxyoctyl derivatives. The immobilized cyclodextrin derivatives were partially evaluated as chiral stationary phases in high-performance liquid chromatography (HPLC) and micro-HPLC.