Sesquiterpene Moiety Research Articles

Sesquiterpene aryl ester natural products in North American Armillaria species

In the first comprehensive study on the secondary metabolism of all ten North American Armillaria species, we analyzed their capacity to produce sesquiterpene aryl ester natural products. All species were identified as producers. Species-specific trends were observed for some species, e.g., for Armillaria ostoyae and A. gemina (low diversity of aryl esters) or A. tabescens (very low number of chlorinated aryl esters). The crude extracts were assayed for antibiotic activity against wood-rotting basidiomycetes and ubiquitous soil fungi. Inhibitory effects were strongly dependent on the target organism, with basidiomycetes being more susceptible than other fungi. Tapinella panuoides and Omphalotus illudens were inhibited by extracts of all Armillaria species whereas the same extracts were completely inactive against Trichoderma harzianum, widely inactive against Mucor racemosus, and only moderately active against Aspergillus flavus and Penicillium oxalicum. Activity tests with seven purified aryl esters suggest that lipophilicity and the position of the double bond in the tricyclic sesquiterpene moiety impact upon bioactivity while the substitution pattern of the aromatic ring does not. Arnamial was the most active compound and showed a minimum inhibitory concentration of <5 μg/ml for all four basidiomycetes and Penicillium oxalicum, but did not inhibit Trichoderma harzianum and Mucor racemosus.

Biologically active sesquiterpene coumarins fromFerulaspecies

Extracts from different species of the genus Ferula (Apiaceae) have had various biomedical applications for many centuries. Many biological features of this genus such as cytotoxicity, antibacterial, antiviral, P-glycoprotein (P-gp) inhibitory and antiinflammatory activity have been attributed to sesquiterpene coumarins; structures containing a common coumarin group and a sesquiterpene moiety. This both highlights the importance of sesquiterpene coumarins as biologically active natural products and necessitates further studies on these compounds. Taking into account the versatile biological properties of compounds isolated from Ferula and the unprecedented interest in the application of natural products as a new generation of therapeutics, the present review will discuss reports on biological activities of sesquiterpene coumarins of the genus Ferula, from 1990 onwards.

ChemInform Abstract: Fissistigmatins A-D: Novel Type Natural Products with Flavonoid-Sesquiterpene Hybrid Structure from Fissistigma bracteolatum

Abstract From Fissistigma bracteolatum Chatt. (Annonaceae), a Vietnamese folk medicinal plant, the novel type natural products fissistigmatin A–D (1–4), being composed of a flavonoid and a sesquiterpene moiety, were isolated. Their structures were elucidated by extensive NMR techniques, MS, CD, molecular modelling calculations and X-ray analysis.

Megalanthine, a bioactive sesquiterpenoid from Heliotropium megalanthum, its degradation products and their bioactivities.

The new bioactive sesquiterpenoid (3R,6E)-2,6,10-trimethyl-3-(3-p-hydroxyphenylpropanoyloxy)-dodeca-6,11-diene-2,10-diol, named megalanthine, was isolated from the resinous exudates of Heliotropium megalanthum. The degradation products of this compound were identified. Several plant-defensive properties (insecticidal, antifungal, and phytotoxic) were evaluated after obtaining positive results in a preliminary etiolated wheat coleoptile bioassay. This bioassay showed the need to have both the phenolic and sesquiterpene moieties of the natural product present to achieve a biological effect. This result was confirmed in phytotoxicity bioassays. Megalanthine was ruled out as a significant plant-plant defense agent because of its lack of stability. The positive results recorded in the antifungal and antifeedant tests suggest, however, that this chemical is relevant in several ecological interactions involving H. megalanthum.

A Cytotoxic Sesquiterpene and Unprecedented Sesquiterpene‐Bisbibenzyl Compounds from the Liverwort Schistochila glaucescens.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A cytotoxic sesquiterpene and unprecedented sesquiterpene-bisbibenzyl compounds from the liverwort Schistochila glaucescens

Extracts of the New Zealand liverwort Schistochila glaucescens were cytotoxic. Bioactivity-directed isolation led to the new sesquiterpene lactone glaucescenolide 1 as the main cytotoxic component with an IC 50 of 2.3 μg/ml against P388 leukaemia cells. Also isolated were three known bisbibenzyls, neomarchantins A 2 and B 3 and marchantin C 4 , which were also cytotoxic (P388 IC 50s 8–18 μg/ml). Two new compounds GBB A 5 and B 6 are the first examples of a bisbibenzyl connected to a sesquiterpene moiety. A biosynthetic route to 1 , 5 and 6 , via a shared intermediate, furanosesquiterpene 7 , is proposed.

Bisabosquals, novel squalene synthase inhibitors. II. Physico-chemical properties and structure elucidation.

The squalene synthase inhibitor bisabosqual A was isolated from the culture broth of Stachybotrys sp. RF-7260, and its structure was determined on the basis of spectroscopic methods including detailed 2D NMR analyses. The structures of bisabosquals B, C and D isolated from Stachybotrys ruwenzoriensis RF-6853 were determined by spectroscopic methods and chemical reactions. The absolute stereochemistry of bisabosquals A, B and D was determined by X-ray crystallographic analysis. They have novel cis-fused tetracyclic structures with a bisabolane-type sesquiterpene and phenol moieties.

Fissistigmatins A–D: Novel Type Natural Products with Flavonoid–Sesquiterpene Hybrid Structure from Fissistigma bracteolatum

From Fissistigma bracteolatum Chatt. (Annonaceae), a Vietnamese folk medicinal plant, the novel type natural products fissistigmatin A–D ( 1– 4), being composed of a flavonoid and a sesquiterpene moiety, were isolated. Their structures were elucidated by extensive NMR techniques, MS, CD, molecular modelling calculations and X-ray analysis.

Isolation of a New Caryophyllane Ester fromLactarius subumbonatus: Conformational Analysis and Absolute Configuration

(1R,6R,9S)-6-Hydroxycaryophyllene (S)-6-hydroxystearate, a sesquiterpene alcohol esterified by the unusual fatty acid (S)-(+)-6-hydroxystearic acid, has been isolated from the fruiting bodies of the Basidiomycete Lactarius subumbonatus. Both NMR data and AM1 calculations indicate that the caryophyllene macrocyclic ring adopts a ββ conformation. The absolute configuration of the sesquiterpene moiety has been established by theoretical Circular Dichroism calculations (De Voe coupled oscillators theory) and that of the fatty acid by NMR studies of the (R)-2-methoxy-2-naphthylacetic acid (2-NMA) ester.

Total synthesis of phenazinomycin and its enantiomer via high-pressure reaction

Total synthesis of phenazinomycin, a rare type of phenazine antibiotic, was achieved by using high pressure reaction. Chiral sesquiterpene moiety in the side chain was synthesized employing ( S)-3-hydroxy-2,2-dimethylcyclohexanone as a chiral source.

Crystal Studies of Avarol Derivatives. 5'-Acetylavarol from Dysidea avara

The X-ray analysis of the natural product 5'-acetylavarol {4-hydroxy-3-[(1,2,3,4,4a,7,8,8a-octahydro-1,2,4a,5-tetramethyl-1-naphthyl)methyl]phenyl acetate, C 23 H 32 O 3 } confirms the previous structure elucidation of Crispino, De Giulio, De Rosa & Stazzullo [J. Nat. Prod. (1989), 52, 646-648], which was made on the basis of chemical and spectral data. Geometrical distortions, with respect to normal tetrahedral values, are evident in the sesquiterpene moiety. The distortions are induced by short contacts between the bulky substituents of the bicyclic system. The hydroquinone ring is nearly perpendicular to the sesquiterpene residue. The crystal packing is characterized by chains of screw-related molecules connected, along the b-axis direction, through repetition of a hydrogen bond that connects hydroxyl groups and acetyl O atoms. The shortest methyl-methyl intermolecular contact is 3.733 (6) A

Pyripyropenes, novel inhibitors of acyl-CoA:cholesterol acyltransferase produced by Aspergillus fumigatus. II. Structure elucidation of pyripyropenes A, B, C and D.

The structures of pyripyropenes A, B, C and D, novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitors, were determined mainly by spectroscopic studies including various NMR measurements. Pyripyropenes have a common structure which consists of pyridine, alpha-pyrone and sesquiterpene moieties. One of the three O-acetyl residues in the sesquiterpene moiety of pyripyropene A is replaced with an O-propionyl residue in pyripyropenes B, C and D.

Structure of phenazinomycin, a novel antitumor antibiotic

Structure and absolute configuration of a novel antitumor antibiotic phenazinomycin was determined on the basis of the spectral data and chemical degradation. Phenazinomycin is the first phenazinone alkaloid which possesses sesquiterpene moiety in its structure.

Structure of the 2,5-dimethyl ether of avarol, a sesquiterpenoid hydroquinone from the marine sponge Dysidea avara

C23H3402, M r = 3 4 2 . 5 3 , monoclinic, P21, a = 1 7 . 2 0 0 ( 9 ) , b = 6 . 5 9 9 ( 4 ) , c = 1 9 . 3 1 6 ( 1 2 ) A , fl = 111.67 (4) ° , V = 2037 (2) A 3, z = 4, D x= I. 12 Mg m -3, 2(Cu Kct) = 1.5418 A, g(Cu Ka) = 0 . 5 0 m m -I, F ( 0 0 0 ) = 7 5 2 , room temperature, final R = 0.056 for 2825 independent observed reflections and 451 parameters. The two independent molecules in the asymmetric unit show identical features except for the different orientation of the hydroquinone fragment with respect to the C I5 sesquiterpene moiety, due to crystal packing requirements. Of the two transconnected six-carbon-atom rings forming the sesquiterpene system the cyclohexene ring A has a conformation intermediate between the sofa and half-chair forms, while the cyclohexane ring B shows a slightly distorted chair conformation. Introduction. The title compound is the 2,5-dimethyl ether of avarol, a sesquiterpenoid hydroquinone extracted from the sponge Dysidea avara (Minale, Riccio & Sodano, 1974). Its absolute stereochemistry has been stated by De Rosa, Minale, Riccio & Sodano (1976) by spectroscopic and chemical methods. Some doubts about the correctness of these assignments were raised by Djura, Stierle, Sullivan, Faulkner, Arnold & Clardy (1980), owing to the inconsistency of physical * Avarol = I IR( 1 ct,2j~,4afl,8afl)]-2-[ ( 1,2,3,4,4a,7,8,8a-octahydroi ,2,4a,5-tetramethyll-naphthalenyl)methyl I1,4-benzenediol. 0108-2701/87/050985-04501.50 data reported for a reaction product common to two different chemical pathways starting from avarol and aureol. Recently, Cariello, De Nicola Giudici & Zanetti (1980) have reported that avarol is active in inducing development aberrations in sea-urchin eggs.

Absolute configurations and circular dichroism of sesquiterpene-coumarin ethers

The absolute stereochemistry of 14 naturally occurring sesquiterpenecoumarin ethers is discussed. In 13 cases the coumarin moiety is isofraxidin (7-hydroxy-6,8-dimethoxycoumarin), in one case scopoletin (7-hydroxy-6-methoxycoumarin). The sesquiterpene moieties belong either to the bicyclic drimenole series or to its consecutive products (methyl migration, ring opening). The CD spectra of all compounds are given. The assignments of the absolute configurations are based on the method ofHoreau, chemical correlation by degradation reactions, extensive comparison of CD data, and biogenetic considerations.

Ilimaquinone, a sesquiterpenoid quinone from a marine sponge

Ilimaquinone ( 1) is a new sponge metabolite of composition C 22H 30O 4. Its structure, which was determined by spectral correlations and X-ray crystallography, comprises a rearranged drimane sesquiterpene moiety linked to a 2-hydroxy-5-methoxybenzoquinone at C-3.

Structures of cochlioquinones A and B, new metabolites of Cochliobolus miyabeanus: chemical and X-ray crystallographic determination

The structures of cochlioquinones A and B, new metabolites isolated from a strain of Cochliobolus miyabeanus, have been determined from chemical, spectroscopic, and crystallographic evidence, the main feature being a p-benzoquinone ring linked to a sesquiterpene moiety and to a C7 side-chain.

Zur Kenntnis der Sesquiterpene und Azulene. 126. Mitteilung. Über die Inhaltsstoffe der Asa foetida I. Farnesiferol A

AbstractFrom the non‐volatile, neutral fraction of Asa foedita (Umbelliferae) 3 isomeric compounds C24H30O4, designated farnesiferol A, B, and C, have been isolated. Farnesiferol A (I) is a mixed ether of umbelliferone with a sesquiterpene moiety of the bicyclofarnesylic type. It might arise biogenetically by oxidative cyclisation of the known umbelliprenine (XXXII).