Germacranolides from Dicoma tomentosa

An investigation of the aerial parts of Dicoma tomentosa afforded four new germacranolides and four melampolides together with urospermal A and its 11β,13-dihydroderivative. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is 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.     

Germacranolides,a guaianolide with a β-lactone ring and further constituents from Grazielia species

An investigation of three Grazielia species afforded, in addition to known compounds, several new sesquiterpene lactones, eight germacranolides, two melampolides and one guaianolide as well as three diterpenes, two geranylgeraniol derivatives and a labda-diene. Three of the sesquiterpene lactones had an additional β-lactone ring, one an acid function, and two others unusual ester functions. The structures were elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.     

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.     

Chemical fingerprinting and antibacterial activity of Saussurea lappa clarke

Costunolide and dehydrocostus lactone of Saussurea lappa are the active compounds having various biological activities used in medicine. HPLC and HPTLC were used for chemical profiling of S. lappa samples collected from different geographical regions of Uttarakhand, India. Costunolide was found to be 0.19 to 0.39% and 0.25 to 0.56% while dehydrocostus lactone was reported in the ranges of 0.27 to 0.70 and 0.50 to 1.06% by HPLC and HPTLC, respectively. Antibacterial activity of methanol extracts of S. lappa was evaluated in order to compare the effects of active constituents against gram positive and negative bacteria. It was determined by well diffusion method. S. lappa exhibited inhibitory effect on bacterial strains with the MICs ranging from 3.12 to 12.50 μg/μL for Escherichia coli and Citrobacter freundii, from 6.25 to 25.00 μg/μL for Enterococcus faecalis and from 6.25 to 50.00 μg/μL for Staphylococcus aureus. It was observed that the samples of S. lappa containing the higher contents of costunolide and dehydrocostus lactone showed the higher antibacterial activity. The results demonstrated that concentrations of both active constituents depended on altitude at which the collected plants were located.     

Germacranolides in Helianthus mollis

Desacetyleupaserrin, eupaserrin and two new germacranolides, mollisorin-A and mollisorin-B, were isolated from H. mollis. ¹H NMR and ¹³C NMR data and chemical interconversions of the four germacranolides are described.     

Sesquiterpene lactones of Artemisia arbuscula and A. tridentata

Chloroform extracts of Artemisia tridentata ssp. vaseyana f. spiciformis (Osterhout) Beetle and Artemisia arbuscula Nutt. ssp. arbuscula gave identical TLC patterns and contained the known germacranolides tatridin-A (I) and tatridin-B (II), and two new germacranolides deacetyllaurenobiolide (III) and spiciformin (IV). The structures of these lactones were shown through spectral studies and chemical transformations. Deacetyllaurenobiolide was converted to the known germacranolide laurenobiolide (IIIb) and spiciformin (IV) was synthesized from deacetyllaurenobiolide along with an isomeric epoxy lactone (V).     

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.     

Sesquiterpene lactones from Helianthus niveus subsp. niveus

Six germacranolides, tirotundin, tagitinin A. orizabin, 8β,14-dihydroxycostunolide and its 14-isobutyrate, and 4β,5-dihydrotagitinin C, were isolated from aboveground parts of Helianthus niveus subsp. niveus. The last two compounds are new.     

Melampolides from Magnolia grandiflora

Two isomeric melampolides, melampomagnolide A and melampomagnolide B, were isolated from the newly formed leaves of Magnolia grandiflora. Their stereochemical structures were established by spectroscopic means, and by chemical correlation with soulangianolide A and parthenolide, respectively.     

Neue kauren-derivate und melampolide aus Smallanthus uvedalia

The investigation of Smallanthus uvedalia afforded, in addition to known compounds, seven new kaurene derivatives and four melampolides. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Tetraludins D to N,eleven new melampolides from Tetragonotheca ludoviciana

Eleven new melampolides, tetraludins D-N, were isolated from aerial parts of Tetragonotheca ludoviciana. Tetraludins D and E, F and G, J and K, and L and M represented epimeric pairs which differed only at one chiral centre of the five-carbon ester side chain at C-8. In benzene-d₆, the ¹H NMR spectra of the diastereomeric pairs of melampolides exhibited well-separated signals in particular for the absorptions due to the ester side chains that differed in chirality.     

Melampolides and germacranolides from Stevia amambayensis

From the aerial parts of Stevia amambayensis in addition to known compounds three new sesquiterpene lactones, a grazielic acid derivative and two melampolides were isolated. The roots gave two new bisabolene derivatives.     

New melampolides,kaurene derivatives and other constituents from Ichthyothere species

The reinvestigation of Ichthyothere terminalis afforded, in addition to known compounds, two new melampolides, a hydroxy borneol, a pinene derivati     

Melampolides from Mikania cordifolia

Aerial parts of two collections ofMikania cordifolia from northern Argentina afforded eight new melampolides whose structures were established by chemical and spectroscopic means. Two of these appear to be mixtures of ester side chain epimers.     

New melampolides and darutigenol from Sigesbeckia orientalis

Isolation and identification of darutigenol and two new melampolides from Sigesbeckia orientalis, in addition to the previously described orientalide and darutoside, are reported.     

Melampolides and other germacranolides from Blainvillea dichotoma

The aerial parts of Blainvillea dichotoma afforded, in addition to known compounds, seven new sesquiterpene lactones, four related to elephantin, two melampolides and a further cis,cis-germacranolide. The chemotaxonomic situation is discussed briefly.     

Germacranolides from Melampodium americanum and Melampodium pilosum

Chemical analysis of Melampodium americanum yielded, besides the known melampodinin A, four new melampolides, melampodinin B, melampodinin C, 9-des     

New germacrolide- and heliangolide-type sesquiterpene lactones from Melampodium linearilobum

Chemical analysis of Melampodium linearilobum yielded, besides coumarin, seven germacrolide-type sesquiterpene lactones, linearilobin A to G and two heliangolides, linearilobin H and I. All new sesquiterpene lactones are oxygenated at C-14 and C-15 and differ by the number and types of ester moieties at C-8, C-14 and C-15. M. linearilobum represents the first species within the genus known to produce germacrolides and heliangolides instead of the more common melampolides.     

Germacranolides from Mikania grazielae

Mikania grazielae afforded two new germacranolides which were identified as 2α-acetoxyeupatolide and 2α-acetoxylaurenobiolide.