Antiproliferative and apoptotic sesquiterpene lactones from Carpesium faberi

Four new (1-4) and 13 known (5-17) sesquiterpene lactones along with two known diterpenes (18, 19) were isolated from the whole plant of Carpesium faberi. The new structures were elucidated by means of spectroscopic techniques and some chemical transformations to be pseudoguaian-1α(H)-8α,12-olide-4β-O-β-d-glucopyranoside (1), 4β,10α-dihydroxy-5α(H)-1,11(13)-guaidien-8α,12-olide (2), 4β,10β-dihydroxy-5α(H)-1, 11(13)-guaidien-8β,12-olide (3), and (4S)-acetyloxyl-11(13)-carabren-8β,12-olide (4). All isolates were tested against MCF-7 human breast cancer cells using the MTT assay. Among them, the sesquiterpene lactones (except tomentosin 17) possessing an α-methylene-γ-lactone moiety were found to have in vitro antiproliferative activities, with IC₅₀ values of 3.0-38.8 μg/mL. The effects of four selected sesquiterpene lactones (guaianolide 2, carabranolide 4, pseudoguaianolide 9, eudesmanolide 13) on the cell cycle were examined using flow cytometry (FCM).     

New sesquiterpene lactones from Inula oculus-christi L.

Investigation of the aerial parts of Inula oculus-christi L. led to the identification of four new sesquiterpene lactones: an eudesmanolide (4α,15α-epoxypulchellin E) and three guaianolides (2α-acetoxy-4α,9β-dihydroxy-1β-guaia-11(13),10(14)-dien-12,8α-olide, 9β,10β-epoxygaillardin, 9α,10α-epoxy-2-epi-gaillardin), in addition to the known gaillardin, pulchellin E, pulchellin C and 3-O-palmitates of 16β-hydroxylupeol, 16β-hydroxy-β-amyrin, and faradiol. The structures of all compounds have been elucidated on the basis of their spectral data.     

Ineupatorolide-like sesquiterpene lactones from Dittrichia viscosa

Dittrichia viscosa afforded, in addition to known compounds, minute amounts of nine sesquiterpene lactones, all closely related to ineupatorolide B     

Koanolides B-D,new sesquiterpene lactones from Koanophyllon gibbosum

Three new germacrane-type sesquiterpene lactones, koanolides B–D (1-3) have been isolated from the aerial parts of Koanophyllon gibbosum (Asteraceae), along with the previously reported sesquiterpene lactone koanolide A and the flavonoid eupatorin. The structures of the new compounds were elucidated using spectroscopic and spectrometric data analyses, including 1D and 2D NMR, and by comparison with known spectral data. The antiproliferative activities of the new compounds were evaluated in a panel of six representative human solid tumor cell lines and showed GI₅₀ values ranging from 1.3 to 16 μM for the new molecules.     

New sesquiterpene lactones from Artemisia herba alba

The structures of herbolides A, B and C, new sesquiterpene lactones isolated from Artermisia herba alba, were determined by chemical and spectroscopic methods.     

Two sesquiterpene lactones from artemisia species

Two new sesquiterpene lactones, himeyoshin and montanone, were isolated from Artemisia feddei and A. montana, respectively and identified by chemical and spectral data as1α,2α-epoxy-3-oxo-5,6-dihydroalantolactone and 1,10-dihydro-11,13-dehydromatricarin.     

Ant-repellent sesquiterpene lactones from Eupatorium quadrangularae

The chloroform extract from the leaves of Eupatorium quadrangularae has been systematically fractionated by following biological activity in a bioassay which measures repellency to the leafcutter ant Atta cephalotes (Formicidae, Attini). Several sesquiterpene lactones were isolated, two of which showed significant ant-repellency.     

Seven sesquiterpene lactones from Ferreyanthus species

The investigation of two Ferreyanthus species afforded seven germacranolides which have not been isolated previously. Two derivatives of linalol were also present. The structures were elucidated by spectroscopic methods. Chemotaxonomic relationships are briefly discussed.     

Two sesquiterpene and three diterpene lactones from Acanthospermum australe

The aerial parts of Acanthospermum australe afforded two new sesquiterpene lactones, an acid and a cis,cis-germacranolide, as well as three diterpene lactones of a new type, most probably formed by intermolecular nucleophilic attack of the carboxyl group of an acid epoxide derived from geranylgeraniol. The structures were proposed on the basis of spectroscopic studies.     

Cytotoxic 7S-oxindole alkaloids from Gardneria multiflora

Seven new oxindole alkaloids, gardmutines A–F (1–6) and 18-hydroxy-chitosenine (7), along with 15 known alkaloids, were isolated from the aerial parts of Gardneria multiflora Makino. The structures of the alkaloids were established by spectroscopic methods. Alkaloids 1–6 are the first Gardneria alkaloids possessing a 7S configuration. Gardmutines D and E were cytotoxic to HeLa, MCF-7 breast, and SW-480 colon cancer cell lines.     

Two sesquiterpene lactones from Trichogonia gardneri

The structures and stereochemistries of two sesquiterpene lactones from Trichogonia gardneri were established as (6R,7S,8S,9S,IOR)-4E-9,10-dihydroxy-8-tigloxygermacr-4-en-6,12-olide) and (5R*,6R*,7S*,8S*,9R*)-14-acetoxy-3-chloro-9-hydroxy-2-oxo-8-tigloxyguia-1(10),3-dien-6,12-of olide by a combination of NMR spectrometry and X-ray diffraction. The results show that the structures of several sesquiterpene lactones which were isolated previously from related species require revision.     

Glaucolide-like sesquiterpene lactones from Cotula cinerea

The aerial parts of Cotula cinerea gave, in addition to widespread compounds, a characteristic diacetylenic spiroketal enolether and several sesquiterpene lactones, three of them being glaucolide-like lactones. The structures were elucidated by highfield ¹H NMR spectroscopy.     

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.     

Two sesquiterpene lactones from Centaurea canariensis

From the aerial part of Centaurea canariensis three sesquiterpene lactones were isolated: cynaropicrin, deacylcynaropicrin and aguerin A. The same species, grown from seed, yielded cynaropicrin, deacylcynaropicrin and aguerin B. The guaianolides aguerin A and B are reported for the first time. Aguerin B was subsequently found to be present in Centaureana linifolia, C. canariensis (var subspinnata) and C. sventenii.     

New types of sesquiterpene lactones and other constituents from Trichogonia species

The investigation of five Trichogonia species afforded seven new furanoheliangolides, three dilactones of a new type, four pairs of epimeric rearra     

Minor sesquiterpene lactones of Helianthus pumilus

The isolation of four known and two new germacradienolides and one known heliangolide from Helianthus pumilus, in addition to the previously report     

The first sesquiterpene lactones esterified with a sesquiterpenic acid

From Hypochoeris glabra two guaianolides esterified with an unusual sesquiterpenic acid were isolated. Proton-catalysed rearrangement of the cyclopropane derivative led to a phenolic acid. The structures were elucidated by high-field ¹H NMR spectroscopy. Further guaianolides were isolated from H. uniflora and Lactuca floridana. These structures were elucidated by spectroscopic methods. The chemotaxonomic situation in the tribe is discussed briefly.     

Biological activities of sesquiterpene lactones

Sesquiterpene lactones are characteristic constituents of the Compositae but also occur sporadically in other angiosperm families and even in some liverworts. These bitter substances often contain as a major structural feature an α,β-unsaturated-γ-lactone, which in recent studies has been shown to be associated with anti-tumor, cytotoxic, anti-microbial and phytotoxic activity. They are known to poison livestock, to act as insect feeding deterrents and to cause allergic contact dermatitis in humans. This review highlights the present state of knowledge on the biological activities and mechanism of action of some sesquiterpene lactones.