Three types of sesquiterpenes from rhizomes of Atractylodes lancea

Eight sesquiterpenes, including four guaiane-types containing an interesting epoxy unit (1-4), a rare tricyclic carbon skeleton-type (5) and three eudesmane-types (6-8), along with five known compounds, were isolated from rhizomes of Atractylodes lancea. The structures and relative configurations of 1-8 were determined by analysis of spectroscopic data, and the absolute configuration of 8 was assigned by application of the CD technique. Compounds 1, 2 and 4 were evaluated for their cytotoxic effects against P388 and A549 cells, but all were inactive. Possible biosynthetic pathways for sesquiterpenes (1-8) were discussed.     

Tricyclic sesquiterpenes from Eremophila georgei

The structures of three new tricyclic sesquiterpenes from Eremophila georgei are described. The absolute stereochemistry of these sesquiterpenes is shown to be antipodal to that of the zizane sesquiterpenes of vetiver oil.     

Structural characterization of phytotoxic terpenoids from Cestrum parqui

Isolation, chemical characterization and phytotoxicity of nine polyhydroxylated terpenes (five C13nor-isoprenoids, two sesquiterpenes, a spirostane and a pseudosapogenin) from Cestrum parqui L'Herr are reported. In this work we completed the phytochemical investigation of the terpenic fraction of the plant and described the structural elucidation of polar isoprenoids using NMR methods. All the configurations of the compounds have been assigned by NOESY experiments. Four new structures have been identified as (3S,5R,6R,7E,9R)-5,6,9-trihydroxy-3-isopropyloxy-7-megastigmene, 5alpha-spirostan-3beta,12beta,15alpha-triol, and 26-O-(3'-isopentanoyl)-beta-d-glucopyranosyl-5alpha-furost-20(22)-ene-3beta,26-diol, and as an unusual tricyclic sesquiterpene. The compounds have been assayed for their phytotoxicity on lettuce at the concentrations ranging between 10(-4) and 10(-7)M. The activities of some compounds were similar to that of the herbicide pendimethalin.     

Chiral recognition of diastereomeric 6-cedrols by vibrational circular dichroism

The use of vibrational circular dichroism spectroscopy for the chiral recognition of the two epimers of 6-cedrol, tricyclic sesquiterpenes, which contains oxygen as the heaviest atom, is shown. Bands in the 1500-850 cm(-1) region of the spectra were analyzed to calculate the anisotropy factors (g), which provided the regions of maximum circular dichroism effect for each epimer.     

The first acetylenic monoterpene and other constituents from Senecio clevelandii

The aerial parts of Senecio clevelandii afforded three new monoterpene lactones, one of them being the first acetylenic monoterpene to be isolated, a C-14 acetylenic angelate, a tetrahydroquinol ester and several known compounds, among them the tricyclic precursor of the polycyclopentanoide sesquiterpenes.     

Bisabolene derivatives and acetylenic compounds from peruvian Coreopsis species

The investigation of three Peruvian Coreopsis species afforded, in addition to compounds isolated previously from this genus, two new tetraynenes and five sesquiterpenes all related to perezone, including a tricyclic ketone with a cedrane skeleton closely related to pipitzol. The structure were elucidated by spectroscopic methods.     

Tricyclic sesquiterpenes and further diterpenes from Espeletiopsis species

The investigation of five Espeletiopsis and two Coespeletia species afforded, in addition to numerous known compounds, two new kaurene derivatives 19-acetoxy-ent-kaurene and 17-oxo-ent-kaur- 15-en-19-oic acid, as well as two new tricyclic sesquiterpenes, one being the previously reported oxidation product of copaborneol and the second one the 5-oxo derivative of silphiperfol-6-ene. The structures were elucidated by NMR studies and by chemical transformations. The chemotaxonomic situation is discussed briefly.     

Inhibitory activity of eudesmane sesquiterpenes from Alpinia oxyphylla on production of nitric oxide

Sixteen eudesmane-type sesquiterpenes including seven new compounds oxyphyllanene A-G (1-2 and 5-9) were isolated from the fruits of Alpinia oxyphylla. Among them, compounds 1-2 are novel trinoreudesmane sesquiterpenes, and 5 is a noreudesmane one. Their structures were established by spectroscopic analysis, including 2D-NMR techniques. Inhibitory activity of compounds 3-8 and 10-16 were tested against nitric oxide production in LPS and IFN-γ-induced RAW 264.7 murine macrophages, and their IC(50) values ranged from 9.85 to 13.95 μg/ml.     

Two sesquiterpene synthases are responsible for the complex mixture of sesquiterpenes emitted from Arabidopsis flowers

Despite the fact that Arabidopsis is largely self-pollinating, its flowers emit a complex mixture of terpene volatiles consisting predominantly of a large group of over 20 sesquiterpenes. Here we report that only two terpene synthases, encoded by the florally expressed genes At5g23960 and At5g44630, are responsible for the formation of virtually all sesquiterpenes found in the Arabidopsis floral volatile blend. Two independent mutant lines with T-DNA insertions in the previously identified At5g23960 gene lacked the emission of three sesquiterpenes, including the main sesquiterpene volatile (E)-beta-caryophyllene, confirming the previous in vitro functional assignment for this gene. Flowers of a mutant line carrying a T-DNA insertion in gene At5g44630 emitted these three sesquiterpenes, but did not emit any of the remaining sesquiterpene volatiles. An At5g44630 cDNA was expressed in Escherichia coli and the produced protein catalyzed the conversion of farnesyl diphosphate into over 15 sesquiterpenes in similar proportions to those found in the floral volatile blend. At5g23960 and At5g44630 promoter-beta-glucuronidase (GUS) fusion experiments demonstrated that both genes are expressed in several parts of the Arabidopsis flower, with strong At5g23960 promoter-GUS activity in the stigma and strong expression of At5g44630 in intrafloral nectaries. Given the previously reported antimicrobial activity of terpenes, their production in stigmas and nectaries may serve to inhibit microbial infection at these vulnerable sites. A survey of 37 Arabidopsis thaliana ecotypes revealed quantitative, but almost no qualitative, variations of floral monoterpene and sesquiterpene emissions suggesting that floral terpene volatiles must play some significant role in the life of the Arabidopsis plant.     

Sesquiterpenes of thalloid liverworts of the genera Conocephalum,Lunularia, Metzgeria and Riccardia

Thalloid liverworts of orders Metzgeriales and Marchantiales elaborate essential oils distinguishable from those of the Jungermanniales by the absence of β-barbatene and anastreptene. Riccardia sinuata elaborates a novel tricyclic exomethylene sesquiterpene of as yet undetermined structure. Conocephalum conicum elaborates cadinene-type sesquiterpenes. β-Cadinene from the latter species is clearly enantiomeric to the same product from vascular plants.     

Sesquiterpenes from Cupressus macrocarpa foliage

Ten sesquiterpenes, many with unusual carbon skeletons, were identified in foliage of Cupressus macrocarpa. These are (-)-10-epi-beta-acoradiene; ent-widdra-2,4(14)-diene; (E)-iso-gamma-bisabolene, i.e., (4E)-4-(1,5-dimethylhex-5-enylidene)-1-methylcyclohexene; (-)-cumacrene, i.e., (4S)-4-[(1R,2S)-2-isopropenyl-1-methylcyclobutyl]-1-methylcyclohexene; (-)-alpha-chamipinene, i.e., (1S,6S,7S)-2,2,6,8-tetramethyltricyclo[5.3.1.01,6]undec-8-ene; and five sesquiterpenes with a 3,3,4'-trimethyl-1,1'-bi(cyclohexyl) skeleton for which the trivial name macrocarpane is proposed. The possible single-enzyme biogenesis of these sesquiterpenes is discussed.     

Total synthesis of (+)-albicanol and (+)-albicanyl acetate.

The drimane sesquiterpenes, (+)-albicanol (2) and (+)-albicanyl acetate (3), were synthesized from an optically active bicyclic diol [(+)-1] that had been obtained via the recently developed optical resolution of a general synthetic intermediate for drimane sesquiterpenes. The crucial step in the previous syntheses was markedly improved by the modified Wittig methylenation of a silyloxy ketone (7). The high overall yield (77% in 4 or 5 steps from (+)-1) by this total synthesis makes it possible to synthesize the other biologically active drimane sesquiterpenes.     

Chemical Constituents of Essential Oil of Two Varieties of Artemisia dubia Wall. ex Bess.

The essential oil of Artemisia dubia var. dubia and dubia var. subdigitata were analysed by GCMS and a tatal of 82 compounds including 50 terpenoids, 12 aromatics and 20 aliphatics were identified, among which variety dubia and var. subdigitata contained 54 and 67 compounds respectivey. Comparative studies indicate that 39 compounds (27 terpenoids, 5 aromatics and 7 aliphatics) were shared by the two varieties. The difference in constituents of essential oil between the two varieties is that more types of biocyclic and tricyclic sesquiterpenes, aromatics and aliphatics were shown inA. Dubia var. subdigitata than A. dubia var. dubia. Compositionally, the terpenoids in essential oil of the two varieties were endowed with a higher degree of cyclization than those of the species from Subgen. Artemisia, but similar to those of the species from Subgen. Dracunculus. Thus the assignment of the two varieties in Subgen. Dracunculus was consistent with the phylogeny of the genus Artemisia.     

Über inhaltsstoffe der tribus mutisieae

An investigation of nine representative species of the tribe Mutisieae yielded some new results of chemotaxonomic interest. Some new sesquiterpenes and coumarins have been characterised by spectroscopic methods. 5-Methylcoumarins appear to be characteristic of the tribe.     

Induced volatiles in elicitor-treated and rice blast fungus-inoculated rice leaves

The volatiles released from elicitor (copper chloride, jasmonic acid, UV, L-methionine and chitosan oligomer)-treated and rice blast fungus-inoculated rice leaves were collected by the solid-phase microextraction technique and analyzed by GC-MS. (Z)-3-Hexen-1-ol, monoterpenes, methyl salicylate, and sesquiterpenes were identified as elicitor-induced volatiles by a comparison of their GC retention times and mass spectra with those of authentic compounds. The different elicitors resulted in some qualitative and quantitative differences in the production of volatiles. Monoterpenes and sesquiterpenes were identified as the rice blast fungus-induced volatiles.     

Cytotoxic terpenoids from Juglans sinensis leaves and twigs

Bioassay-guided fractionation of an 80% MeOH extract of Juglan sinensis leaves and twigs has resulted in the isolation of three new triterpenes (1-3) and two new sesquiterpenes (4-5) along with two known sesquiterpenes (6-7). The new compounds were determined to be 3β, 11α, 19α, 24, 30-pentahydroxy-20β, 28-epoxy-28β-methoxy-ursane (1), 1α, 3β-dihydroxy-olean-18-ene (2), 2α, 3α, 23-trihydroxy-urs-12-en-28-oic acid 28-O-β-d-glucopyranoside (3), (4S, 5S, 7R, 8R, 14R)-8, 11-dihydroxy-2, 4-cyclo-eudesmane (4), 15-hydroxy-α-eudesmol-11-O-β-d-glucopyranoside (5), by spectroscopic analysis. The cytotoxicity of compounds (1-7) against four cancer cell lines such as B16F10, Hep-2, MCF-7 and U87-MG was evaluated. Compounds 1, 2, 6 and 7 showed potent cytotoxicity against all of four cancer cell lines, respectively.     

New terpenoids from Maytenus apurimacensis as MDR reversal agents in the parasite Leishmania

Two new sesquiterpenes (1-2) and one new lupane triterpene (3) have been isolated from the roots of Maytenus apurimacensis. The novel beta-dihydroagarofurans are the first sesquiterpenes with a basic polyhydroxy skeleton of 15-deoxyalatol and 4,15-dideoxyalatol that show high MDR reversing activity in the protozoan parasite Leishmania tropica.     

Synthesis and evaluation of tricyclic pyrrolopyrimidinones as dipeptide mimetics: inhibition of interleukin-1beta-converting enzyme

The application of a tricyclic pyrrolopyrimidinone scaffold for the synthesis of peptidomimetic inhibitors of interleukin-1beta-converting enzyme (ICE) is reported. The synthesis of the tricyclic scaffold and conversion of it to a variety of target ICE inhibitors were accomplished in 4-5 steps. In vitro biological evaluation of the tricyclic pyrrolopyrimidinones revealed fair to good ICE inhibitors, with the most active compound exhibiting an IC50 of 14 nM in a caspase-1 enzyme binding assay.     

Potent bisimidazole-based HCV NS5A inhibitors bearing annulated tricyclic motifs

This Letter describes the synthesis and biological evaluation of a number of functionalized bisimidazoles bearing annulated tricyclic motifs as potent inhibitors of HCV NS5A protein. Compound 4h, which contains a substituted tricyclic 6-6-6 xanthene, demonstrated broad genotypic spectrum, compelling potency, and good oral bioavailability with dose-dependent drug exposure level in multiple animal species.     

The synthesis and biological activity of certain pentaazaacenaphthylenes, hexaazaacenaphthylenes and their corresponding nucleosides

Synthesis of the tricyclic nucleoside 8-amino-6-N-methyl-2-(beta-D-ribo-furanosyl)-1,2,3,5,6,7-hexaazaacena phthylene (5) has been accomplished by the ring closure of an appropriately substituted pyrazolo[3,4-d]-pyrimidine nucleoside followed by the requisite chemical conversions. The formation, isolation and structural elucidation of two unexpected nucleosides formed by a reductive ring cleavage of the hexaazaacenaphthylene ring system is discussed. A comparison of the antitumor and biological activity of 5 with the structurally related tricyclic pentaazaacenaphthylene nucleoside which is currently in phase II clinical trials at the 5'-phosphate pro-drug is also presented.