Spatial structures of the sesquiterpene germacrane lactones tanachin and tamirin

An x-ray investigation has been made of the sesquiterpene lactones tanachin and tamarin: diffractometer, CuK-radiation, 845 and 981 reflections, respectively, direct method, R factors 0.064 and 0.065. The conformations of both molecules are boat-boat with configurations of the¹D₁₄ and¹⁵D₅ types.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Institute of Bioorganic Chemistry, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodynkh Soedinenii, No. 2, pp. 198–204, March–April, 1989.     

The sesquiterpene lactones ofStizolophus balsamita

Summary From the epigeal part ofStizolophus balsamita (Lam.) Cass. ex Takht. a new sesquiterpene lactone balsamin has been isolated with the composition C₂₀H₂₆O₆, mp 242–244°C (from ethanol), [] _D ¹⁷ –45.70° (c 1.9; chloroform). Do the basis of the basis of the IR, UV, and PMR spectra of balsamin and its acetate, a stereochemical structure has been proposed for balsamin, and the structures of stizolin and stizolicin isolated previously from the same plant have also been supplemented by stereochemistry.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 467–472, July–August, 1976.     

Epoxidation of sesquiterpene lactones tourneforin and ludartin

Epoxy derivatives of the sesquiterpene lactones ludartin and tourneforin were synthesized. Their structures were elucidated using spectral data and x-ray structure analysis.     

Advances in the chemistry of sesquiterpene lactones

The paper gives a review of the chemistry of natural sesquiterpene lactones.     

Dimeric sesquiterpene lactones : Structure of absinthin

Absinthin, a constituent of $\text{A}$. $\text{absinthium}$, has been given structure $\text{2}$.     

Fragmentation of sesquiterpene lactones related to leucomisin

The mass spectra of seven sesquiterpene lactones — leucomisin, austricin, parishin B, parishin C, matricarin, artelin, and artelin diacetate — have been studied. It has been shown that the presence of the conjugated bonds C(1)=C(10), C(2)=0, and C(3)=C(4), and also C(5)=C(6), stabilizes M⁺, and the main fragmentation process is that of the splitting out of the lactone ring. The presence of hydroxy substituents at C(3) and C(8) of the guaiane system does not change the stability of M⁺ under electron impact. The directions of fragmentation have been confirmed by an analysis of spectra obtained by the metastable defocussing of daughter ions and by measuring the accurate masses of the main peaks of the fragmentary ions.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 96–101, January–February, 1987.     

Two new sesquiterpene lactones from Ixeris sonchifolia

The structures of two new sesquiterpene lactones, 11,13beta-dihydroixerin Z (1) and Ixerin Z2 (2) isolated from Ixeris sonchifolia were determined to be 3-hydroxy-1(10),3-guaiadiene-12,6-olide-2-one-3-O-beta-D-glucopyranoside and 1(10),3,11 (13)-guaiatriene-12,6-olide-2-one-3-O-[6'-(4"-hydroxybenzyl lactyl)]-beta-D-glucopyranoside, respectively on the basis of detailed spectral analysis.     

Two new sesquiterpene lactones from Sonchus arvensis

Two new sesquiterpene lactones, 1β,15-diacetoxy-5,7α,6,11β(H)-eudesm-3,4-en-6,12-olide (1) and 1β-hydroxy-3,4-en-15-O-β-glucopyranosyl-5,7α,6,11β(H)-eudesman-6,12-olide (2), were isolated from Sonchus arvensis L. (Asteraceae), together with ten known compounds. Their structures were elucidated through spectroscopic and chemical methods. All these known compounds except oleanolic acid (11) were isolated from the genus Sonchus for the first time. Selected new compounds were evaluated for antibacterial activity; unfortunately, they showed weak or no activities against Streptococcus mutans ATCC 25175.     

Two new sesquiterpene lactones from Ixeris chinensis

Phytochemical investigation of Ixeris chinensis NAKAI (Asteraceae) has resulted in the isolation of a new guaianolide-type sesquiterpene lactone, ixerochinolide (1) as well as the related glucoside, ixerochinoside (2). In addition, the known guaianolides, 8beta-hydroxy-3-oxo-guaia-4(15),10(14),11(13)-trien-1alpha,5alpha,6beta,7alphaH-12,6-olide (8beta-hydroxydehydrozaluzanin), 8beta,15-dihydroxy-2-oxo-guaia-1(10),3,11(13)-trien-5alpha,6beta,7alphaH-12,6-olide (lactucin), 3beta,8alpha,10alpha-trihydroxy-guaia-4(15),11(13)-dien-1alpha,5alpha,6beta,7alphaH-12,6-olide (10alpha-hydroxy-10,14-dihydro-desacylcynaropicrin) and 3beta-D-glucopyranosyloxy-8beta-(p-hydroxyphenylacetyloxy)-guaia-4(15),10(14),11(13)-trien-1alpha,5alpha,6beta,7alphaH-12,6-olide (8-epicrepioside) were identified. The structures were determined on the basis of spectral analyses, especially 1- and 2D NMR. Compound 1 exhibited significant cytotoxicity against human PC-3 tumor cells.     

Conformational analysis of sesquiterpene lactones of germacrane type

The structure of 1(10)Z,4Z-germacranolides was studied by the method of molecular mechanics. Possible conformers, the probability of their existence, and barriers to conformational transitions were determined. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 268–271, February, 1997.     

The sesquiterpene lactones from achillea fragrantissima,I. Achillolide A and B,two novel germacranolides

With the aid of one- and two-dimensional multipulse NMR techniques the structure of two novel sesquiterpene lactones from Achillea fragrantissima growing in Israel were elucidated and their conformational behaviour investigated. Although both compounds are closely related in their structures their CD spectra indicate that they belong to different enantiomeric series.     

Structure of new sesquiterpene lactones from Inula germanica

Summary It has been established that the substance isolated previously fromInula germanica L. is a mixture of two new sesquiterpene lactones: germanin A and germanin B.On the basis of chemical reactions and a study of IR, UV, NMR, and mass spectra, structures (I) and (XVI), respectively, are proposed for germanin A and germanin B.All-Union Scientific-Research Institute of Medicinal Plants. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 578–589, September–October, 1974.     

Antimalarial activity of sesquiterpene lactones from Vernonia cinerea

Two new sesquiterpene lactones, vernolides C and D as well as six known ones were isolated from the dichloromethane fraction of an aqueous extract from Vernonia cinerea. Their structures were elucidated by spectroscopic methods. Among the known sesquiterpene lactones, three of them were described in this plant for the first time. In vitro antiplasmodial evaluation showed that the three major compounds 1, 7 and 8 were active against chloroquine resistant Plasmodium falciparum strain (W2) with IC(50) 3.9, 3.7 and 3.5 microM, respectively.     

Structure of new sesquiterpene lactones from Inula germanica

Chemistry of Natural Compounds - It has been established that the substance isolated previously fromInula germanica L. is a mixture of two new sesquiterpene lactones: germanin A and germanin B. On...     

Further cytotoxic sesquiterpene lactones from Elephantopus mollis KUNTH

Three new sesquiterpene lactones, (4betaH)-5alpha-hydroxy-8alpha-(2-methylbut-2-enoyloxy)-2-oxo-1(10),11(13)-guaiadien-12,6alpha-olide (1), (4betaH)-8alpha-(2-methylbut-2-enoyloxy)-2-oxo-1(5),10(14),11(13)-guaiatrien-12,6alpha-olide (2) and 2,5-epoxy-2beta-hydroxy-4alpha-methoxy-8alpha-(2-methylbut-2-enoyloxy)-4(15),10(14),11(13)-germacratrien-12,6alpha-olide (3), have been isolated from roots and stems of Elephantopus mollis together with two known sesquiterpene lactones (4, 5). The identification of the isolates was accomplished by spectroscopic methods. Compounds (1-5) exhibited significant cytotoxic activities against mouse neuroblastoma B104 cells.     

Unusual sesquiterpene lactones from Ligularia virgaurea spp. oligocephala

[structure: see text] [structure: see text] Sesquiterpene lactones, ligulolide A (1) and 6beta,8alpha-dihydroxy-1-oxoeremophila-7(11),9(10)-diene-12,8-olide (2), were isolated from Ligularia virgaurea spp. oligocephala. Their structures were established by analysis of one- and two-dimensional NMR data. The relative stereostructures were determined on the basis of NOESY and single-crystal X-ray experiments. 1 represents a novel sesquiterpene carbon framework, and a possible biosynthetic process is proposed. 2 is a novel eremophilane-type sesquiterpene.     

Gaigranin and gaigrandin — New sesquiterpene lactones fromGaillardia grandiflora

Two new sesquiterpene lactones — gaigranin and gaigrandin — have been isolated from the epigeal part ofGaillardia grandiflora, and their structures have been established on the basis of spectral (IR, PMR,¹³C NMR, and mass) characteristics and x-ray structural analysis.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 79–85, January–February, 1995. Original article submitted October 7, 1994.     

Rhaposerine and rhaserolide, new sesquiterpene lactones fromRhaponticum serratuloides

Two new crystalline guaianolides,viz., rhaposerine and rhaserolide, were isolated from an ethanolic extract of the above-ground part of the plantRhaponticum serratuloides by column chromatography along with sesquiterpene lactones,viz., centaurepensin and acroptilin, which have been found in other plants. The chemical structures of the title lactones were established by¹H and¹³C NMR spectroscopy and 2D¹H−¹H (COSY) and¹³C−¹H (COSY and COLOC) NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2010–2014, October, 1999.