Sesquiterpene lactone from Salmalia malbarica

A new cadalane type sesquiterpenoid, 1, 6-dihydroxy-3-methyl-5-(1-methylethyl)-7-methoxy-8-carboxylic acid (8 → 1 lactone) has been isolated from a 50% aqueous methanolic extract of 6–9 months old cultivated roots of Salmalia malbarica (Bombax malbaricum).     

Sesquiterpene lactone glucosides from Sonchus asper

From the methanolic extract of the roots of Sonchus asper, two new sesquiterpene glucosides, together with two known sesquiterpene glucosides and a known aglycone were isolated. Structures were identified as 11beta,13-dihydrourospermal A, 15-O-beta-D-glucopyranosyl-11beta,13-dihydrourospermal A, 15-O-beta-D-glucopyranosylurospermal A, 15-O-[6'-(p-hydroxyphenylacetyl)]-beta-D-glucopyranosylurosperm al A and 14-O-methylacetal-15-O-[6'-(p-hydroxyphenylacetyl)]-beta-D-+ ++glucopyranosylurospermal A, by spectroscopic means.     

Sesquiterpene lactone glycosides from Crepis capillaris

Four new sesquiterpene lactone glucosides, in addition to known compounds, have been isolated from the roots of Crepis capillaris and their structures elucidated on the basis of spectral analysis and hydrolytic studies.     

Sesquiterpene lactone glucosides and alkyl glycosides from the fruit of cumin

From the polar portion of the methanolic extract of cumin (fruit of Cuminum cyminum L.), two sesquiterpenoid glucosides, cuminoside A and B, and two alkyl glycosides were isolated together with five known compounds. Their structures were established as (1S,5S,6S,10S)-10-hydroxyguaia-3,7(11)-dien-12,6-olide beta-D-glucopyranoside, (1R,5R,6S,7S,9S,10R,11R)-1,9-dihydroxyeudesm-3-en-12,6-olide 9-O-beta-D-glucopyranoside, methyl beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside and ethane-1,2-diol 1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside, respectively.     

Sesquiterpene lactone variability in Parthenium hysterophorus L

A population of Parthenium hysterophorus collected in Salta Argentina afforded two ambrosanolides, 2beta-hydroxycoronopilin and 1alpha,2beta,4beta-trihydroxypseudoguaian-6beta,12-olide, as well as five known others. Plants of the fructification from those transplanted from the Puna Argentina at 1200 m over the sea level produced hymenin.     

Sesquiterpene lactone and diterpene constituents of helianthus annuus

One new furanoheliangolide derivative, 4,5-dihydroniveusin A, as well as the known compounds niveusin B and argophyllin A and B, were isolated from a Texas population of Helianthus annuus. Three previously characterized diterpene acids, grandifloric acid, ciliaric acid and 17-hydroxy-ent-isokaur-15(16)-en-19-oic acid were the principal constituents of this population.     

Euphane and friedelane triterpenoids from Tripterygium wilfordii

Four hitherto unknown triterpenoids, including one euphane, namely wilfordeuphone (1), and three friedelanes, namely wilforic acids G − I (2–4), were isolated from the ethanol extract of the roots of Tripterygium wilfordii. The absolute configuration of 1 was established by single crystal X-ray diffraction. In addition, this study is the first to report euphane-type triterpenoid in the genus Tripterygium. Compound 1 exhibited the moderate cytotoxic activity when evaluated against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480), with IC50 values ranging from 14.0–26.7 μM.     

Sesquiterpene lactone patterns in diploid and polyploid Ambrosia dumosa

Diploid, tetraploid and hexaploid populations of Ambrosia dumosa yielded several different sesquiterpene lactone patterns. The distribution of chemical complements is useful in relating the different levels of this polyploid series.     

Sesquiterpene lactone stereochemistry influences herbivore resistance and plant fitness in the field

Background and Aims

Stereochemical variation is widely known to influence the bioactivity of compounds in the context of pharmacology and pesticide science, but our understanding of its importance in mediating plant–herbivore interactions is limited, particularly in field settings. Similarly, sesquiterpene lactones are a broadly distributed class of putative defensive compounds, but little is known about their activities in the field.

Methods

Natural variation in sesquiterpene lactones of the common cocklebur, Xanthium strumarium (Asteraceae), was used in conjunction with a series of common garden experiments to examine relationships between stereochemical variation, herbivore damage and plant fitness.

Key Results

The stereochemistry of sesquiterpene lactone ring junctions helped to explain variation in plant herbivore resistance. Plants producing cis-fused sesquiterpene lactones experienced significantly higher damage than plants producing trans-fused sesquiterpene lactones. Experiments manipulating herbivore damage above and below ambient levels found that herbivore damage was negatively correlated with plant fitness. This pattern translated into significant fitness differences between chemotypes under ambient levels of herbivore attack, but not when attack was experimentally reduced via pesticide.

Conclusions

To our knowledge, this work represents only the second study to examine sesquiterpene lactones as defensive compounds in the field, the first to document herbivore-mediated natural selection on sesquiterpene lactone variation and the first to investigate the ecological significance of the stereochemistry of the lactone ring junction. The results indicate that subtle differences in stereochemistry may be a major determinant of the protective role of secondary metabolites and thus of plant fitness. As stereochemical variation is widespread in many groups of secondary metabolites, these findings suggest the possibility of dynamic evolutionary histories within the Asteraceae and other plant families showing extensive stereochemical variation.     

Sesquiterpene lactone from Wunderlichia crulsiana inhibits the respiratory burst of leukocytes triggered by distinct biochemical pathways

The sesquiterpene lactone tubiferin was chemically purified from the brazilian native plant Wunderlichia crulsiana and identified by NMR and GC/MS data. Its ability to inhibit the respiratory burst of peritoneal inflammatory polymorphonuclear leukocytes (PMN) stimulated upon addition of phorbol miristate acetate (PMA), opsonized zymosan (OZ), and N-formyl-methionyl-leucyl-phenylalanine (fMLP) was evaluated. The tubiferin inhibition was more pronounced when PMN were stimulated through the protein kinase C pathway (PMA) compared to the alternative complement pathway (OZ). The inhibition when PMN were triggered by a chemoattractant stimulus (fMLP) was similar to that achieved with OZ-stimulated phagocytes. Tubiferin showed dose-dependent effects on the PMN respiratory burst triggered by the three different substances, and also decreased substantially the carrageenan-induced mice paw edema.     

Further cycloartane and friedelane triterpenoids from the leaves of Caloncoba glauca

Three new triterpenoids, caloncobic acid C (1), caloncobalactone C (2) and glaucalactone B (3) were isolated from the leaves of Caloncoba glauca. Their structures were elucidated on the basis of spectroscopic evidence. These compounds were evaluated for their inhibitory activities against human and mouse 11β-hydroxysteroid dehydrogenase type 1 and type 2.     

Ovalifolone A and B: New friedelane derivatives from Garcinia ovalifolia

Two new friedelane type triterpenoids, ovalifolone A (1) and ovalifolone B (2), together with eight known compounds were isolated from the stem bark of Garcinia ovalifolia. Their structures were established on the basis of mass spectrometric, NMR data and by the comparison with literature data. Some of the isolated compounds were evaluated for their cytotoxicity and antibacterial activities and garcinane showed interesting activity against Artemia salina with LD₅₀ value of 2.69 μg/mL.     

Sesquiterpene lactone dehydroleucodine selectively induces transient arrest in G2 in Allium cepa root meristematic cells

Dehydroleucodine is a sesquiterpene lactone recently isolated from aerial parts of a medicinal herb, Artemisia douglasiana Besser. We have previously shown that 25 and 100 microM dehydroleucodine slowed down onion root growth by 30 and 70%, respectively, affecting neither cell viability nor cell elongation. In the present study we analyze the effect of dehydroleucodine on cell cycle phases in onion (Allium cepa L.) root meristematic cells synchronized with caffeine or caffeine and hydroxyurea. Synchronized root cells treated with 100 and 200 microM dehydroleucodine present an interphase lengthening of 5.2 h and 8.2 h, respectively. The S-phase length, estimated by [3H]thymidine incorporation assay, was 6 h for both control roots and roots that had been immersed in dehydroleucodine. The peak of [3H]leucine incorporation was observed 6 h after release from synchronization in controls and in dehydroleucodine-treated roots, indicating that protein synthesis in G2 was not affected. Thus, these results show that dose-dependently dehydroleucodine selectively induces a transient arrest of meristematic cell in G2 and that dehydroleucodine can be used experimentally as a cell cycle suppressor.     

Sesquiterpene lactones from Inezia integrifolia

Inezia integrifolia afforded, in addition to known compounds, three new eudesmanolides and a guaianolide. Two of the eudesmanolides were obtained as a mixture. The relative position of the ester groups could not be determined with certainty. The chemotaxonomy is discussed briefly.     

Sesquiterpene xylosides from Iphiona scabra

The aerial parts of Iphiona scabra afforded a complex mixture of sesquiterpene xylopyranosides. Separation of the peracetylated derivatives gave 10 compounds, seven eudesmane derivatives, a secoeudesmane and two sesquiterpene glycosides with new skeletons, named iphionane and isoiphionane. The biogenesis of these compounds is discussed.     

Sesquiterpene lactones from Carphochaete bigelovii

Five sesquiterpene lactones with C₁₀-diester side-chains have been identified as major constituents of a leaf surface extract of Carphochaete bigelovii. The structures were elucidated by spectroscopic methods and are reported for the first time. Chemosystematic implications are discussed briefly.