Volatile components from European liverworts Marsupella emarginata,M. aquatica and M. alpina

The hydrodistillation products of the liverworts Marsupella emarginata, M. aquatica and M. alpina were investigated by spectroscopic methods. A number of new compounds could be isolated by preparative gas chromatography (GC) and identified by spectroscopic techniques including GC-mass spectrometry, NMR and chemical correlations in conjunction with enantioselective GC. From M. emarginata, in addition to many known compounds, the sesquiterpene hydrocarbon (-)-7-epi-eremophila-1(10),8,11-triene (1) and the sesquiterpene derivatives (-)-4-epi-marsupellol (2), (-)-marsupellol acetate (18), (-)-4-epi-marsupellol acetate (4), (+)-5-hydroxymarsupellol acetate (5) and (-)-9-acetoxygymnomitr-8(12)-ene (24) could be identified. In M. aquatica the sesquiterpene hydrocarbons (-)-myltayl-8(12)-ene (7), ent-(+)-amorpha-4,11-diene (8), (-)-amorpha-4,7(11)-diene (9), the sesquiterpene alcohol (+)-9-hydroxyselina-4,11-diene (10) and (-)-2-acetoxyamorpha-4,7(11)-diene (11) were identified. In M. alpina (-)-trans-selina-4(15),11-dien-5-ol (12), (+)-8,9-epoxyselina-4,11-diene (13) and (+)-cis-selina-4(15),11-dien-5-ol (14) were found as new natural products.     

Sesquiterpene constituents from the essential oil of the liverwort Plagiochila asplenioides

The essential oil of the liverwort Plagiochila asplenioides from two different locations in Northern Germany were investigated by chromatographic and spectroscopic methods. Seven compounds were isolated by preparative gas chromatography (GC) and their structures investigated by mass spectrometry (MS), NMR techniques and chemical correlations in combination with enantioselective GC. In addition to known constituents, aromadendra-1(10),3-diene, two aromatic sesquiterpene hydrocarbons, bisabola-1,3,5,7(14)-tetraene and bisabola-1,3,5,7-tetraene, three sesquiterpene ethers, muurolan-4,7-peroxide, plagiochilines W and X, in addition to ent-4-epi-maaliol, could be identified as natural compounds for the first time.     

Variability in chemical constituents in Petasites hybridus from Austria

Petasites hybridus (Asteraceae), butter bur, is an ancient medicinal plant with spasmolytic sesquiterpene esters. Two chemotypes, the petasine and the furanopetasine chemotype, occur in Austria. The first one is considered as pharmaceutically useful due to its spasmolytic constituents, but it is restricted to the northern parts of the Alps. This use, however, is impaired by the presence of low amounts of toxic pyrrolizidine alkaloids (PA), mainly senecionine and intergerrimine. PA are usually concentrated in the metabolically active parts of the complex rhizome which are the thickenings just below the leaves. They are also present in flower stalks but are almost absent in leaf buds, the petioles and the leaf blades. The alkaloids showed a great variability within and between populations; the values recorded ranged from less than 2 to 500mgkg(-1) PA, median PA of 77 populations varied from 2 to 191mgkg(-1) in the rhizomes. In nearly 25% of the samples analysed the PA content was below 10mgkg(-1), another 25% had between 10 and 20mgkg(-1) PA. Histograms of PA concentrations in a population often showed a distinct skewness toward lower alkaloid contents. Alkaloid content was independent of sesquiterpene chemotype. The seasonal influence on PA content of rhizomes was little in comparison to the variability within the population or within the rhizome itself. Nevertheless, when comparable rhizome parts within a population were considered, the PA content may remain stable over several years. Although plants totally free of PA could not yet be found, it is possible to select populations low in alkaloids. Several populations of the petasine chemotype containing less than 10mgkg(-1) in the rhizomes could be found in the area investigated.     

The sesquiterpene hydrocarbons of maize (Zea mays) form five groups with distinct developmental and organ-specific distributions

The sesquiterpene hydrocarbon chemistry of maize (Zea mays) inbred line B73 was analyzed by both direct solvent extraction and headspace sampling. In seedlings, 15 olefinic compounds were identified, and 21 olefins were detected in mature plants after anthesis. Both solvent extracts and collections of headspace terpenes were found to contain the same compounds in the same relative proportions suggesting that there is no selective barrier to release from plants. Approximately 25% of the stored pool was found to be released from young seedlings per hour. The individual sesquiterpenes varied extensively in their abundance among different organs and developmental stages. Compounds could be divided into five different groups such that the members of each group always occur together in the same constant ratios to one another. Each group has a distinct distribution pattern. Group A includes the two dominant compounds, (E)-beta-farnesene and alpha-bergamotene, and appears only after herbivore damage in seedlings, but is constitutively present in the leaves and husks after anthesis. The major compounds of group B, including alpha-copaene, germacrene D and delta-cadinene, were present throughout the seedling but found only in husks of mature plants. The group C compounds, beta-bisabolene and an unknown sesquiterpene olefin, are restricted to the roots. The presence of group D and E compounds was confined to the leaves and husk of mature plants. The complex sesquiterpene mixture of group D is identical to the products formed by the previously identified terpene synthase TPS4, suggesting that each of the four other sesquiterpene hydrocarbon mixtures may also represent the products of a single terpene synthase.     

Inhibition of testosterone secretion by S-petasin in rat testicular interstitial cells

S-petasin, a kind of sesquiterpene ester, is the anti-inflammatory ann analgesic component of the butterbur (Petasites hybridus). The clinical benefit of S-petasin is the spasmolytic activity, but its side effects on the reproductive endocrinology are not clear yet. The present study was to explore the effects of S-petasin on the secretion of testosterone in vivo and in vitro. We found that single intravenous injection of S-petasin (1 microg/kg) decreased basal plasma testosterone concentration in adult male rats. The enzymatically dispersed rat testicular interstitial cells were incubated with S-petasin (0-4.3 x 10(-5)M) in the presence or absence of human chorionic gonadotropin (hCG, 0.05 IU/ml), forskolin (adenylyl cyclase activator, 10(-5) M), and androstenedione (testosterone biosynthesis precursor, 10(-9) M) at 34 degrees C for 1 h. The concentrations of testosterone in the incubation medium were measured by radioimmunoassay. S-petasin at 4.3 x 10(-7) M was effective to reduce the basal and hCG-stimulated release of testosterone in rat testicular interstitial cells. The stimulatory effects of testosterone secretion induced by forskolin and androstenedione were significantly reduced by S-petasin at 4.3 x 10(-5) M and 4.3 x 10(-6) M, respectively. These results suggest that S-petasin inhibits the production of testosterone in rat testicular interstitial cells in part through diminishing the activities of adenylyl cyclase and 17-ketosteroid reductase.     

Comparison of the feeding deterrent activity of some sesquiterpene lactones and a lignan lactone towards selected insect storage pests

Four sesquiterpene lactones isolated from Eurpatorium cannabinum, Homogyne alpina and Petasites albus (all Compositae), together with two of their adducts, as well as one lignan lactone of dibenzylbutanolide type from Libocedrus yateensis (Cupressaceae), were tested for their feeding deterrent activity against the adults of Sitophilus granarius and Tribolium confusum, as well as against the larvae of Tribolium confusum and Trogoderma granarium. The strongest deterrent activity against all species was exhibited by the lignan lactone yatein and the sesquiterpene spirolactone bakkenolide A. Both may be included to the class of very good insect feeding deterrents. The comparison presented here showed that the conjugated α-exomethylene moiety of the lactone ring was not the decisive factor for the deterrent activity in the investigated test model.     

Sesquiterpene lactones,waxes and volatile compounds from Artemisia herba-alba subspecies Valentina

The structures of two sesquiterpene lactones isolated from Artemisia herba-alba subsp. valentina have been determined by spectroscopic methods. One of these was dihydroreynosin, the other was a new compound assigned the name torrentin. The chemical compositions of a wax and a hydrocarbon fraction from the essential oil have also been investigated.     

Terpenoids from Microliabum polymnioides

The phytochemical study of M. polymnioides led to the isolation of two sesquiterpene lactones namely: 11alphaH-dihydrozaluzanin E and 1beta-hydroxy-4-oxo-11betaH-4-noreudesman-6,12-olide. Their structures were determined by spectroscopic methods. The relative stereochemistry was established by a combination of coupling constant analysis, NOESY correlations and molecular modeling. Three related known sesquiterpene lactones were also identified, and these data were used for chemotaxonomical purposes.     

Probing sesquiterpene hydroxylase activities in a coupled assay with terpene synthases

5-epi-Aristolochene dihydroxylase (EAH) catalyzes unique stereo- and regiospecific hydroxylations of a bicyclic sesquiterpene hydrocarbon to generate capsidiol. To define functional and mechanistic features of the EAH enzyme, the utility of a coupled assay using readily available sesquiterpene synthases and microsomes from yeast overexpressing the EAH enzyme was determined. Capsidiol and deoxycapsidiol biosyntheses were readily measured in coupled assays consisting of 5-epi-aristolochene synthase and EAH as determined by the incorporation of radiolabeled farnesyl diphosphate into thin-layer chromatography-isolated products and verified by gas chromatography-mass spectrometry analysis. The assays were dependent on the amounts of synthase and hydroxylase protein added, the incubation times, and the presence of nicotinamide adenine dinucleotide phosphate. The utility of this coupled assay was extended by examining the relative efficiency of the EAH enzyme to catalyze hydroxylations of different sesquiterpene skeletons generated by other terpene synthases.     

Sesquiterpenes from the east African sandalwood Osyris tenuifolia

The essential oil of the east African sandalwood Osyris tenuifolia was investigated by chromatographic and spectroscopic methods. Beside several already known sesquiterpenes four new compounds could be isolated by preparative gas chromatography and their structures investigated by mass spectroscopy and NMR techniques. Two of the new compounds--tenuifolene (17) and ar-tenuifolene (15)--show a new sesquiterpene backbone. 2,(7Z,10Z)-Bisabolatrien-13-ol (23) and the cyclic ether lanceoloxide (21) belong to the bisabolanes.     

Sesquiterpene lactones and other constituents from Matricaria chamomilla L.

An ethanolic extract of the aerial parts of Matricaria Chamomilla L. collected at Oued Tonga near El-Kala is eastern Argelia yielded two new substances named matricolone and chamolol, together with four known compounds. The structure of the new compounds were determined by chemical transformations and NMR spectroscopy with ¹H-¹H (COSY and ROESY), ¹H-¹³C (one bond and long range correlations) two dimensional experiments. The results obtained indicate the presence of sesquiterpene lactones of the eudesmanolide, germacranolide and guaianolide types. These products can be considered to be of great interest from a chemotaxonomical point of view for this wild-growing plant, because these types of lactones have not been found together in other Matricaria species.     

Insecticidal sesquiterpene pyridine alkaloids from Euonymus species

Three insecticidal sesquiterpene pyridine alkaloids with a beta-dihydroagarofuran sesquiterpene skeleton, euoverrine A (1), B (2), and euophelline (3), and a known compound, euojaponine C (4), were isolated from the root bark of Euonymus verrucosides, E. fortunei and E. phellomana by bioassay-guided fractionation. Their chemical structures were elucidated mainly by analyses NMR and MS spectral data.     

A sesquiterpene hydrocarbon from the bogwoods of Cryptomeria japonica D. Don, presumably formed by diagenetic hydrogenation

Structure of an hitherto unknown component of the essential oils from two bogwoods of Cryptomeria japonica D. Don was determined by mass spectrometry and NMR analyses. It was identified as cadina-1(10)-ene, a new cadinane-type sesquiterpene hydrocarbon with a single double bond.     

Effects of S-petasin on corticosterone release in rats

Petasites hybridus is used in Chinese herbal medicine. S-petasin is a bioactive compound isolated from leaves or roots of Petasites hybridus. S-petasin has been used to relieve gastrointestinal pain, lung disease, and spasms of the urogenital tract. However, the side effect of S-petasin on endocrine systems are still not clear. This study explored the effects of S-petasin on the release of corticosterone in vivo and in vitro. An intravenous injection of S-petasin (10 microg/kg) decreased both basal and adrenocorticotropin (ACTH)-induced plasma corticosterone concentration in male rats. In vitro, S-petasin (3 x 10(-6) - 10(-4) M) caused a significant reduction of basal and ACTH-stimulated release of corticosterone from the enzymatically dispersed rat zona fasciculata-reticularis (ZFR) cells in a dose-dependent manner. In order to study possible mechanisms, ZFR cells were incubated with S-petasin (10(-5) M) in the presence or absence of forskolin (adenylate cyclase activator, 10(-6) - 10(-4) M), 8-Br-cAMP (a cAMP analogue, 10(-6) 10(-4) M), 25-OH-cholesterol (pregnenolone biosynthesis precursor, 10(-5) M) combined with trilostane (a blocker of 3beta-hydroxysteriod dehydrogenase, 3beta-HSD, 10(-6) M) and deoxycorticosterone (corticosterone biosynthesis precursor, 10(-9) - 10(-6) M) at 37 degrees C for 1h. The concentration of pregnenolone and corticosterone in media were measured by radioimmunoassay. The stimulatory effects of corticosterone secretion induced by forskolin (10(-5) - 10(-4) M), 8-Br-cAMP (10(-5) - 10(-4) M) and deoxycorticosterone (10(-7) - 10(-6) M) were reduced by S-petasin at 10(-5) M. The stimulatory effects of pregnenolone secretion induced by 25-OH-cholesterol combined with or without trilostane was reduced by S-petasin at 10(-5) M. These results suggest that S-petasin inhibits the production of corticosterone from rat ZFR cells in part through decreasing the activities of adenylyl cyclase, P450scc and 11beta-hydroxylase.     

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.     

Studies on the chemical composition and biological activity of essential oil from Cyperus rotundus Linn.

The sesquiterpene caryophyllene in its alcohol form has been identified for the first time from the essential oil of the tubers of Cyperus rotundus Linn. The structure of the alcohol has been identified by spectroscopic and chemical methods. Bioefficacy of the oil and its hydrocarbon, ketonic and alcoholic fractions is reported for maize and mungbean.     

New melampolide sesquiterpene lactones from Melampodium leucanthum

The isolation of five germacranolide sesquiterpene lactones from Melampodium leucanthum Torrey and Gray (Compositae-Heliantheae) is reported. The structures of three new melampolides, melampodin-A acetate, leucanthin-A and leucanthin-B, have been determined by spectral methods and chemical correlations.     

Exploring biosynthetic diversity with trichodiene synthase

Trichodiene synthase is a terpenoid cyclase that catalyzes the cyclization of farnesyl diphosphate (FPP) to form the bicyclic sesquiterpene hydrocarbon trichodiene (89%), at least five sesquiterpene side products (11%), and inorganic pyrophosphate (PP(i)). Incubation of trichodiene synthase with 2-fluorofarnesyl diphosphate or 4-methylfarnesyl diphosphate similarly yields sesquiterpene mixtures despite the electronic effects or steric bulk introduced by substrate derivatization. The versatility of the enzyme is also demonstrated in the 2.85A resolution X-ray crystal structure of the complex with Mg(2+) (3)-PP(i) and the benzyl triethylammonium cation, which is a bulkier mimic of the bisabolyl carbocation intermediate in catalysis. Taken together, these findings show that the active site of trichodiene synthase is sufficiently flexible to accommodate bulkier and electronically-diverse substrates and intermediates, which could indicate additional potential for the biosynthetic utility of this terpenoid cyclase.     

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.     

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.