Ent-kaurane Diterpenes Research Articles

Diterpenes from Sideritis argyrea

The known ent-kaurene diterpenes 1–9 and a new ent-labdane, ent-6β,8α-dihydroxylabda-13(16),14-diene (10), were isolated from the whole plant of Sideritis argyrea. Their structures were elucidated based on one- and two-dimensional NMR techniques and HRMS.

Ent-Kaurene Diterpenes from Sideritis Athoa

Two new and six known ent-kaurene diterpenes were isolated from the whole plant of Sideritis athoa and their structures were elucidated as ent-3α, 18-dihydroxykaur-16-ene (1), athonolone (2), ent-3β-hydroxykaur-16-ene (3) ent-3β,7α-dihydroxykaur-16-ene (4), 7-epicandicandiol (5), linearol (6), foliol (7) and sidol (8) based on 1D and 2D NMR techniques and HRMS.

Kaurene diterpenes from Mikania vitifolia

From the aerial parts of Mikania vitifolia three new ent-kaurane diterpenes, ent-7 α-cinnamoyloxy-15β-hydroxy-kaur-16-en-19-oic acid, ent-15 β-cinnamoyloxy-7α-hydroxy-kaur-16-en-19-oic acid and ent-15 β-hydroxy-7 α-( E)-lachnophylloyloxy-kaur-16-en-19-oic acid were isolated together with the known ent-kauranes ent-kaur-16-en-19-oic acid, ent-kaur-16-en-19-ol, ent-15 β-hydroxy-kaur-16-en-19-oic acid and ent-15 α-cinnamoyloxy-kaur-16-en-19-oic acid. The structures were established by mass spectrometry, 1H NMR and partly 13C NMR spectroscopy.

Diterpenes and sesquiterpenes from Mikania banisteriae

Two new ent-kaurane diterpenes, 18,19-diacetoxy- ent-kaur-16-ene and 17-oxo- ent-kaur-15(16)-en-18-oic acid, were isolated from the aerial parts of Mikania banisteriae, together with the known ent-kauranes ent-kaur-16-en-18-oic acid and ent-kaur-16-en-18-ol. The structures were established by mass spectrometry, 1H NMR and partly 13C NMR spectroscopy. In addition, the sesquiterpene lactones eudesma-4(15),7(11)-dien-8β,12-olide and eudesma-4(15),7(11),8(9)-trien-12-olide as well as the sesquiterpenes 1β,6α-dihydroxyeudesm-4(15)-ene and caryophylleno-xide were identified by direct comparison (TLC, GC, GC-MS) with authentic samples. The chemotaxonomic significance is briefly discussed. ent-Kaur-16-en-18-oic acid and ent-kaur-16-en-19-oic acid showed no antifeedant, antimicrobial and antiinflammatory properties. © 1997 Elsevier Science Ltd. All rights reserved

Termite antifeedant activity in Xylopia aethiopica

A hexane extract of Xylopia aethiopica fruits and an aqueous methanol extract of the seeds were studied for termite antifeedant activity against workers of the subterranean termite, Reticulitermes speratus. The crude extract, at 1%, exhibited strong antifeedant activity in a choice filter paper disk bioassay. Bioassay-directed fractionation led to the isolation and identification of six ent-kaurane diterpenes in the hexane extract. Feeding deterrent activity varied significantly with the structures when the compounds were tested at concentrations ranging from 5000 ppm (40 μg cm −2) to 100 ppm (0.824 μg cm −2). (−)-Kaur-16-en-19-oic acid had the strongest termite antifeedants activity among the ent-kauranes isolated. Two phenolic amides and four lignanamides were also isolated from the aqueous methanolic extract of seeds. E-3-(4-hydroxy-3-methoxyphenyl)- N-2-[4-Hydroxyphenylethyl]2-Propenamide was more active than E-3-(3,4-dihydroxyphenyl)- N-2-[4-Hydroxyphenylethyl]2-propenamide, whilst grossamide and the new lignanamide, demethylgrossamide, as well as (−)-cannabisins B and D exhibited potent feeding deterrent activity at 5000 ppm. The identity of these compounds was established by spectroscopic analysis and synthesis. Two synthetic amides, E-3-(3,4-methylenedioxyphenyl)- N-2-[4-Hydroxyphenylethyl] propenamide and E-3-(3,4-methylenedioxyphenyl)- N-2-[octadecyl]-2-propenamide were also tested for antifeedant activity.

Terpenes from Aristolochia triangularis

Phytochemical examination of Aristolochia triangularis led to the isolation of allantoin, nerolidol, sitosterol, dibenzylbutyrolactone type lignans and ent-kaurane type diterpenes. This is the first report on the isolation of ent-kaurane from a natural source.

Chemosystematics of Di- and sesquiterpenoids in polypodiaceous ferns

The sesqui- and diterpenoid chemistry of Copeland's Pteridaceae gives information useful for understanding the phylogenetic relationships and taxonomic affinities between pteridaceous ferns. Indalane-type sesquiterpenes, pterosins, are distributed widely among the Pteridaceae, but the distribution is limited to this family. This fact shows the phylogenetic homogeneity of Copeland's Pteridaceae. Z-type pterosins (C 15) occur more commonly than B-type (C 14) pterosins in the primitive ferns and B-type pterosins are more common in the advanced ferns. Various ent-kaurane type diterpenes occur mainly in the Pteris and related genera. Among them are 2 β-hydroxy- ent-kauranes, which are characteristic of advanced members of the genus Pteris and ent-kauran-19-oic acids which are characteristic of primitive members of the genus. The relationship between chemistry and the groupings of Pteris on the basis of frond shapes is discussed. Chemotaxonomy of Monachosorum and Plagiogyria is also described

Diterpenes from sideritis infernalis

Five new ent-kaurene diterpenes, episinfernal, sinfernal, sinfernol, epoxysinfernol and canditriol, and the known one, candol B, candicandiol and candidiol, have been isolated from the aerial parts of Sideritis infernalis.

Three ent-kaurene diterpenes from Vellozia caput-ardeae

Three new ent-kaurene diterpenes have been isolated from the roots and stem of Vellozia caput-ardeae. Their structures were elucidated by spectroscopic methods as ent-9β-hydroxy kaur-16-ene, ent-11α-hydroxy kaur-16-ene and ent-9β,11α-dihydroxy kaur-16-ene.

Chemotaxonomic significance of ent-kaurene diterpenes in Rabdosia umbrosus varieties

Quantitative identification of six ent-kaurene diterpenes, by reverse phase HPLC, in crude ether extracts of a single leaf of five major Rabdosia umbrosus varieties is described. These diterpenes are significant chemosystematic markers among these plants.

Chemische und chemotaxonomische Untersuchungen von Filices. XXXIII. Chemische Untersuchungen der Inhaltsstoffe von Pteris longipes Don.

From the fronds of Pteris longipes DON two known and five new ent-kaurane type diterpenes were isolated. The structures of the new diterpenes, pterokaurene L1, L2, L3, L4 and pterokaurane L5, were established respectively as ent-9-hydroxy-15-oxo-kaur-16-en-19-oic acid, ent-9, 15α-dihydroxy-kaur-16-en-19-oic acid, ent-9-hydroxy-kaur-16-en-19-oic acid, ent-12α, 15α-dihydroxy-kaur-16-en-19-oic acid and ent-11α, 16α-epoxy-16R-kauranoic acid by spectroscopic methods, some chemical transformations and X-ray crystallographic analysis.