New germacranolides and other sesquiterpene lactones from Dicoma species

Two subspecies of Dicoma anomala afforded, in addition to known compounds, an eudesmanolide, a guaianolide and four germacranolides, the latter being closely related 8, 12-lactones. D. schinzii gave three new germacranolides and D. zeyheri a pair of isomeric acetylenic compounds. The structures were elucidated by highfield ¹H NMR spectroscopy. The chemotaxonomic situation of this genus is discussed briefly.     

Seven germacranolides and four eudesmanolides from Tithonia rotundifolia

The aerial parts of Tithionia rotundifolia afforded, in addition to two known sesquiterpene lactones, eleven new ones, seven germacranolides and four eudesmanolides. The structures were determined by ¹H NMR spectroscopy.     

Sesquiterpene lactones from helogyne hutchisonii

The aerial parts of Helogyne hutchisonii afforded, in addition to known sesquiterpene lactones, two new heliangolides and two germacranolides. The structures were elucidated by high-field ¹H NMR spectroscopy.     

Germacranolides from anvillea garcini

The aerial parts of Anvillea garcini afforded three germacranolides, two of which had not being isolated previously. The structures were elucidated by ¹H NMR spectroscopy. The configuration of 9-acetoxy parthenolide at C-9 has been revised.     

Five germacranolides from Gochnatia discoidea

The investigation of two further Gochnatia species afforded five new germacranolides, all being 8,12-lactones. The structures were elucidated by intensive ¹H NMR studies and by some chemical transformations. The chemotaxonomic aspects are discussed briefly.     

Zwei neue germacranolide aus Artemisia argentea

The aerial parts of Artemisia argentea afforded, in addition to known compounds (arborescin, artemetin, sitosterol and lirioresinol-B-dimethyl ether), two new germacranolides, closely related to ketopelenolide, also isolated from an Artemisa species. The structures were elucidated by intensive ¹H NMR studies and by some chemical transformations.     

Six guaianolides from Stylotrichium rotundifolium

The investigation of Stylotrichium rotundifolium afforded the epoxide of β-sesquiphellandrene, a new derivative of geranylnerol and six guaianolides not isolated previously. Furthermore, two germacranolides also present in a Lasiolaena species and several known compounds were isolated. The structures were elucidated by detailed ¹H NMR investigations. The chemotaxonomic situation is discussed briefly.     

Germacranolides from Viguiera microphylla

Three new germacranolides, including two heliangolides (niveusin C-2′,3′-epoxide and 1,2-dehydroniveusin C-2′,3′-epoxide) and a germacrolide (3β-hydroxy-8β-epoxyangeloyloxycostunolide-1β,10α-epoxide) were isolated from Viguiera microphylla. Their structures were established by spectroscopic analyses, including extensive ¹H NMR and ¹³C NMR decoupling experiments and chemical transformations. X-ray diffraction analysis confirmed the structure of niveusin C-2′,3′-epoxide.     

Sesquiterpene lactones and other constituents from Tanacetum parthenium

A reinvestigation of the aerial parts of Tanacetum parthenium afforded in addition to known compounds three pinene derivatives, two spiroketal enol ether polyines, four germacranolides; and six guaianolides, two of them being endoperoxides, and two secoguaianolides. The structures were elucidated by high field ¹H NMR spectroscopy, mass spectroscopy and a few chemical transformations. The biogenetic relationships are discussed briefly.     

Acanthospermolides and other constituents from Blainvillea acmella

The aerial parts of Blainvillea acmella afforded, in addition to widespread triterpenes, desacetyl ovatifolin, desacyl grazielic acid tiglate, 8β-[2-methylbutyryloxy]-9β-hydroxy-14-oxo-acanthospermolide, four new germacranolides and seven acanthospermolides. The roots gave ovatifolin, two widespread thiophenacetylenes and two daucane derivatives. Comparison of the data with those of cyclochaenin required a revision of its structure. The structures were elucidated by high field ¹H NMR spectroscopy. Biogenetic relationships and taxonomic aspects are discussed briefly.     

Millerenolides,sesquiterpene lactones from Milleria quinqueflora

The aerial parts of Milleria quinqueflora afforded 17 new germacranolides (five melampolides and 12 millerenolides), two ent-pimarene and two ent-kaurene derivatives as well as two alicyclic diterpenes and a galactoside. The structures were elucidated by NMR spectroscopy. The chemotaxonomic situation is discussed.     

Guaianolides,heliangolides, diterpenes and cycloartenol derivatives from Balsamorhiza sagittata

Investigation of the aerial parts of Balsamorhiza sagittata afforded 12 new sesquiterpene lactones, five guaianolides, three heliangolides, three germacranolides and two geranylnerol derivatives. From the roots eight cycloartane derivatives, a hydroxylanosterone and hexacos-1-ene were isolated. Structures were elucidated mainly by spectroscopic methods, especially high field NMR. The chemotaxonomic situation is discussed briefly.     

Neue kaurensäure-derivate und germacranolide aus Montanoa pteropoda

The investigation of Montanoa pteropoda afforded in addition to known kaurene-derivatives three new ones and three germacranolides, which most probably have the structures as shown. The structures are elucidated by extensive ¹H-NMR studies and some chemical transformation. The chemotaxonomical situation is discussed briefly.     

Deuteron NMR spectroscopy of copper(II) complexes in solution. 1. (5,7,7,12,14,14,-hexamethyl-1,4,8,1 1-tetraazacyclotetradeca-4,11-diene)-copper(II) and its derivatives in nonaqueous solvent

¹H and ²H NMR spectra of the title copper(II) complexes and its derivatives have been measured. In contrast with their ¹H NMR spectra, ²H NMR spectra gave well resolved sharp signals, and demonstrated that two diastereomers attributable to two asymmetric ligand nitrogens are readily resolved. The remarkable linewidth-narrowing was found in the peripheral methyl groups, which make ²H NMR spectra very useful even for copper(II) complexes with a long electron spin relaxation time. By using ²H NMR spectra, meso-racemate equilibrium was pursued and examined in aqueous and acetonitrile solutions.     

Further sesquiterpene lactones from costa rican eupatorieae

The aerial parts of Ayapana elata afforded two new germacranolides. The configuration at C-3 in one of them was the same as that of some bejaranolides, the structures of which therefore have to be revised. Critonia quadrangularis gave in addition to known compounds three elemanolides, a germacranolide, an isodaucane derivative and tremetone derivative. Critonia hebebotrya contained large quantities of known diterpene acids. Koanophyllon pittieri gave two epimeric ent-labdanes. The structures were elucidated by highfield NMR spectroscopy.     

Two new germacranolides from Elephantopus tomentosus

The bioassay-guided chemical investigation of the whole plant of Elephantopus tomentosus led to the isolation of two new germacranolides, tomenphantopin C (1) and tomenphantopin D (2), together with four known compounds (3–6). Their structures were determined by spectroscopic techniques (UV, IR, MS, 1D and 2D NMR). All compounds were evaluated for cytotoxic and antibacterial activities.     

Synthesis and conformational analysis of carbasugar bioisosteres of α-l-iduronic acid and its methyl glycoside

The synthesis of two novel carbasugar analogues of α-l-iduronic acid is described in which the ring-oxygen is replaced by a methylene group. In analogy with the conformational equilibrium described for α-l-IdopA, the conformation of the carbasugars was investigated by ¹H and ¹³C NMR spectroscopy. Hadamard transform NMR experiments were utilised for rapid acquisition of ¹H,¹³C-HSQC spectra and efficient measurements of heteronuclear long-range coupling constants. Analysis of ¹H NMR chemical shifts and J_H,H coupling constants extracted by a total-lineshape fitting procedure in conjunction with J_H,C coupling constants obtained by three different 2D NMR experiments, viz., ¹H,¹³C-HSQC-HECADE, J-HMBC and IPAP-HSQC-TOCSY-HT, as well as effective proton-proton distances from 1D ¹H,¹H T-ROE and NOE experiments showed that the conformational equilibrium ⁴C₁?²S_5a?¹C₄ is shifted towards ⁴C₁ as the predominant or exclusive conformation. These carbasugar bioisosteres of α-l-iduronic acid do not as monomers show the inherent flexibility that is anticipated to be necessary for biological activity.     

Three germacranolides and other constituents from Eremanthus species

The re-investigation of Eremanthus glomerulatus afforded three new germacranolides and a guaianolide, while from E. mollis two known furanoheliangolides and a new phenylpropanol derivative were isolated. The germacranolides most probably are precursors of the widespread glaucolides. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Sulcatine,a norsesquiterpene from the fungus Laurilia sulcata

The structure of sulcatine, a novel protoilludene norsesquiterpene isolated from a culture of Laurilia sulcata, has been assigned on the basis of a detailed study of its ¹H NMR and ¹³C NMR spectra and chemical evidence. The relative configuration was deduced from the observed ¹H {¹H} nuclear Overhauser effects (NOEs) and from the values of ¹H¹H coupling constants. The application of the exciton chirality method on the dibenzoate permitted establishment of the absolute configuration of sulcatine as 2S,3R,7S,8S,9R.     

One-dimensional 13C NMR and HPLC-1H NMR techniques for observing carbon-13 and deuterium labelling in biosynthetic studies

For several decades isotope labelling techniques have been the indispensable tools used to unravel pathways of secondary product biosynthesis. NMR spectroscopy, together with mass spectrometry, is the most effective measuring technique used in the analysis of metabolites enriched with stable isotopes. ²H and ¹³C are the NMR-detectable nuclides which have been most frequently employed in plant secondary metabolite synthesis. Examples from the biosynthesis of phenylpropanoids, phenylphenalenones, and glucosinolates are used when discussing some aspects of one-dimensional NMR analysis of metabolites selectively labelled with ²H and ¹³C. Besides direct NMR detection of ¹³C-enriched metabolites, special emphasis is placed on indirect detection of ¹³C and ²H, especially by HPLC-¹H NMR coupling, to analyse the isotopomer pattern of compounds in low concentration. The examples discussed in this paper were obtained from studies with Anigozanthos preissii (root cultures) (Haemodoraceae) and Eruca sativa (Brassicaceae).