Further 6,12-cis-Germacranolides and Eudesmanolides from Montanoa Species

Abstract

The aerial parts of Montanoa hihiscifolia afforded, in addition to known compounds, twelve new germacranolides, all being 6,12-cis-lactones, as well as a new type of sesquiterpene lactone, obviously closely related to one of the germacranolides. Furthermore, a new prostaglandin-like compound was found together with one previously known. From Montanoa dumicola two 6,12-m-germacranolides, as well as two 6,12-c/f-eudesmanolides and a geranyl phloracetophenone derivative, were isolated. The structures and the stereochemistry of all compounds were elucidated by their pmr spectral data. Biogenetic relationships are discussed briefly.Montanoa hihiscifolia (Benth.) Sch. Bip. (Compositae, tribe Heliantheae, subtribe Montanoinae) has been studied previously leading to the isolation of three trans, transgermacra-1( 10),4-dien-aí-6,12-olides (1), which at that time were rare and reported simultaneously from only an Ursinia species (2). Similar lactones are also present in Montanoapteropoda and Montanoa atriplicifolia (3). We have studied again . hihiscifolia, now collected in Costa Rica along with Montanoa dumicola Klatt. In addition to one of the lactones isolated previously, seventeen new ones were identified.The aerial parts of M. hihiscifolia from Costa Rica afforded, after careful separation of the extract, in addition to widespread compounds (see Experimental), the epoxy angelare 13 (1), together with the germacranolides 1-12, the lactone 14, and the prostaglandin-like compounds 21 (4) and 22. The structure of 13 clearly followed from X 13

Jasmonates: key players in the plant defence

“…It was then shown 25 to be endogenous in sunflower seedlings. Subsequent identifications have been made in a number of plant species during the course of routine natural product screening programs [26][27][28][29][30] and as part of focussed studies 31,32 on the occurrence of this compound and its isomers. As discussed above for JA, 12-oxo-PDA can similarly equilibrate via the enol (at C-13) to the more stable trans-arrangement of the side chains.…”

“…A number of metabolites and analogues of 5 and 6 have also been reported. These include chromomoric acid (13-hydroxy-5), 26,35 14-hydroxy-5, 29 13,14-didehydro-5, 26,27 9-hydroxy-13,14-didehydro-5 26 and 11-hydroxy-6. 27 The acetylenic and allenic analogues, dicranenones A and B 1 7 and 8, are interesting compounds that have been isolated from Dicranium mosses.…”

Sesquiterpene Lactones from Montanoa hibiscifolia That Inhibit the Transcription Factor NF-κB

“…(Asteraceae, tribe Heliantheae, subtribe Montanoinae), also called tree daisy, is an erect, little branched shrubby perennial originated from an area extending from Guatemala to Costa Rica . It is known for the occurrence of sesquiterpene lactones (Sls) of the germacranolide type as well as the unusual montahibisciolides. − In continuation of our search for Sls with potential antiinflammatory activity we reinvestigated the aerial parts of M. hibiscifolia collected in Costa Rica. The lipophilic extract was separated using common column chromatography (CC) in addition to low-pressure chromatography (see Experimental Section).…”

Brominated Oxylipins and Oxylipin Glycosides from Red Sea Corals

“…They are similar to chromomoric acids B and F, isolated from Chromolaena morii and C. chasleae. [17,18] Chromomoric acid B methyl ester has also been found in other species such as Schistostepnium, [19] Montanoa, [20] and [a] 309 modified Mosher method. The compounds gave positive results in a brine shrimp toxicity assay, a sea urchin eggs test (Paracentrotus lividus), and a crown gall tumor on potato disks test (Agrobacterium tumefaciens).…”