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.     

Labdane and eudesmane derivatives from Ageratum fastigiatum

Several diterpenes, triterpenes, ent-labdanes, and eudesmane derivatives have been isolated from Ageratum fastigiatum. A previously unknown eud     

New diterpenes from Sideritis sicula

Two new diterpenes have been isolated from Sideritis sicula: sideripol, ent-18-acetoxy-7α-hydroxykaur-15-ene and epoxysideritriol, ent-15β,16β-epoxykauran-7α,17,18-triol. The previously known diterpene eubol, ent-7α-acetoxykaur-16-en-15β,18 diol has also been obtained from the same source.     

Euphorbia and Momordica metabolites for overcoming multidrug resistance

Multidrug resistance (MDR) is the major obstacle for cancer chemotherapy. MDR is a multifactorial phenomenon that can result from several mechanisms, including an increased drug efflux, due to overexpression of P-glycoprotein (P-gp) that transports anticancer drugs out of the cells. Thus, the role of this transporter has made it a therapeutic target and the development of P-gp modulators considered among the most realistic approaches for overcoming P-gp-mediated MDR. Many other strategies have been proposed. One of them is the identification of compounds that selectively kill multidrug resistant cells. In our search for MDR modulators from plants, the P-gp inhibition ability of a large number of compounds on resistant cancer cells was evaluated. These compounds, presented in this review, comprise mainly diterpenes, triterpenes and phenolic derivatives. The most relevant results were obtained from two sets of compounds: macrocyclic diterpenes with the jatrophane and lathyrane scaffold, and triterpenes of the cucurbitane-type isolated from Euphorbia species and Momordica balsamina L., respectively. Additionally, some of those macrocyclic diterpenes, and ent-abietane diterpenic lactones, also isolated from Euphorbia species, were found to be selectively toxic to drug-resistant phenotypes.     

Beyerene derivatives and other constituents from Petunia patagonica

Two new diterpenes of the beyerene type, ent-19-hydroxy-1 7-acetoxybeyer-15-ene and ent-beyer-15-en-17-oic acid, and two previously characterized kauranoids, ent-16β-hydroxy-17-acetoxykaurane and ent-16β,1 7-dihydroxy-kaurane, as well as two known flavonoids, luteolin-7,3′,4′-trimethyl ether and luteolin-7,3′-dimethyl ether, and a triterpenoid, oleanoic acid, were obtained from a chloroform extract of Petunia patagonica. The new structures were elucidated by spectral data and chemical transformations.     

Ent-labdane derivatives from gutierrezia grandis

Two new diterpenes, 3α-angeloyloxy-18-hydroxy-13-furyl-ent-labda-8(17)-ene and 3α-hydroxy-18-angeloyloxy- 13-furyl-ent-labda-8(17)-ene and an only recently reported third diterpene, 3α, 18-dihydroxy-13-furyl-ent-labda-8(17)-ene, were isolated from the leaves of Gutierrezia grandis. Their structures were determined by mass spectral, IR, ¹H NMR and ¹³C NMR data was well as chemical evidence.     

茯苓中三萜类和多糖类成分的研究进展

主要对中药茯苓中的三萜类和多糖类成分进行了综述。到目前为止已从茯苓的菌核和菌丝中分离到三萜类物质39个,其中羊毛甾-8-烯型三萜12个,羊毛甾-7,9(11)-二烯型三萜16个,3,4-开环-羊毛甾-7,9(11)-二烯型三萜7个,3,4-开环-羊毛甾-8-烯型三萜2个,三环二萜类1个,齐墩果烷型三萜1个;分离到多糖类物质23个。     

Foliage diterpenes of Dacrydium Intermedium: identification,variation and biosynthesis

The major diterpenes in the foliage of Dacrydium intermedium have been identified as rimuene, ent-rosadiene, ent-beyerene, phyllocladene, ent-kaurene, sclarene and ent-sclarene. ent-Rosadiene and ent-sclarene have not been reported previously from natural sources. Considerable tree-to-tree variations are encountered and genetic control is proposed. Biosynthetic mechanisms are put forward to explain the presence of diterpenes of both enantiomeric series. A lack of mono- and sesquiterpenes in both D. intermedium and D. fonkii, which ties in with Quinn's proposed revision of the Dacrydium genus, is also noted.     

Diterpenes and tetranorditerpenes from Acritopappus species

The investigation of four Acritopappus species afforded twenty-three new diterpenes of the labdane or kolavane type and three tetranorditerpenes as well as two new benzofuran derivatives and a hydroxybicyclogermacrene. The structures were elucidated by spectroscopic methods and by some chemical transformations. Though the absolute configuration were not established in all cases, most probably all diterpenes were ent-labdanes or kolavanes (clerodanes). The chemotaxonomic importance of this investigation is discussed briefly.     

The microbiological transformation of some ent-3β-hydroxykaur-16-enes by Gibberella fujikuroi

The preparation of ent-3β-hydroxykaur-16-ene from linearol and of ent -3β,18-dihydroxykaur-16-ene from foliol is described. The microbiological transformation of these and of foliol by Gibberella fujikuroi has been studied. A 3α-hydroxyl group appears to exert an inhibitory effect on transformations involving oxidation at C-19.     

Comparison of ent-kaurene and ent-isokaurene synthesis in cell-free systems from etiolated shoots of normal and dwarf-5 maize seedlings

An active cell-free system, prepared from young etiolated shoots of normal Zea mays seedlings, was shown to biosynthesize the terpenoid hydrocarbons ent-kaur-16-ene, squalene and phytoene from mevalonic acid. The biosynthesis of ent-kaur-16-ene from mevalonic acid was compared using cell-free systems obtained from normal and dwarf-5 seedlings. ent-Kaur-16-ene was the predominant diterpene hydrocarbon synthesized by extracts from the normals; however, ent-kaur-15-ene was the major diterpene hydrocarbon synthesized by the dwarf-5 mutants. ent-Kaur-15-ene and ent-kaur-16-ene were also produced as minor products in the normal and dwarf-5 systems, respectively. The possible significance of the synthesis of the ‘wrong isomer’ (ent-kaur-15-ene) by the mutant is discussed.     

Biotransformation of 7α-hydroxy- and 7-oxo-ent-atis-16-ene derivatives by the fungus Gibberella fujikuroi

The microbiological transformation of 7α,19-dihydroxy-ent-atis-16-ene by the fungus Gibberella fujikuroi gave 19-hydroxy-7-oxo-ent-atis-16-ene, 13(R),19-dihydroxy-7-oxo-ent-atis-16-ene, 7α,11β,19-trihydroxy-ent-atis-16-ene and 7α,16β,19-trihydroxy-ent-atis-16-ene, while the incubation of 19-hydroxy-7-oxo-ent-atis-16-ene afforded 13(R),19-dihydroxy-7-oxo-ent-atis-16-ene and 16β,17-dihydroxy-7-oxo-ent-atisan-19-al. The biotransformation of 7-oxo-ent-atis-16-en-19-oic acid gave 6β-hydroxy-7-oxo-ent-atis-16-en-19-oic acid, 6β,16β,17-trihydroxy-7-oxo-19-nor-ent-atis-4(18)-ene and 3β,7α-dihydroxy-6-oxo-ent-atis-16-en-19-oic acid.     

Diterpenoids from sideritis pusilla subsp. flavovirens

Several new 14-hydroxybeyerene acetates have been isolated from the aerial parts of Sideritis pusilla subsp. flavovirens. In addition, an ent-kaur-15-ene (siderol) and a new ent-7α, 18-dihydroxybeyer-15-ene (flavovirol) have been obtained from the same source. The structures of these new acetates have been established by chemical and spectroscopic means and the structure of flavovirol has been confirmed by ¹³C NMR.     

Metabolism of kaurenoids by Gibberella fujikuroi in the presence of the plant growth retardant,N,N,N-trimethyl-1-methyl-(2′,6′,6′-trimethylcyclohex-2′-en-1′-yl)prop-2-enylammonium iodide

The plant growth retardant, N,N,N-trimethyl-1-methyl-(2′,6′,6′-trimethylcyclohex-2′-en-1′-yl)prop-2-enylammonium iodide, is shown to block gibberellin biosynthesis in Gibberella fujikuroi between mevalonate and ent-kaur-16-ene, probably by inhibiting ent-kaur-16-ene synthetase A-activity. In the presence of the plant growth retardant, cultures of the fungus incorporate (26.5%) added ent-[¹⁴C]-kaur-16-ene into gibberellin A₃. Under the same conditions kaur-16-ene, 13β-kaur-16-ene, and ent-kaur-15-ene are not metabolised to gibberellin analogues.     

Biotransformation of ent-kaur-16-ene and ent-trachylobane 7β-acetoxy derivatives by the fungus Gibberella fujikuroi (Fusarium fujikuroi)

Candol A (7β-hydroxy-ent-kaur-16-ene) (6) is efficiently transformed by Gibberella fujikuroi into the gibberellin plant hormones. In this work, the biotransformation of its acetate by this fungus has led to the formation of 7β-acetoxy-ent-kaur-16-en-19-oic acid (3), whose corresponding alcohol is a short-lived intermediate in the biosynthesis of gibberellins and seco-ring ent-kaurenoids in this fungus. Further biotransformation of this compound led to the hydroxylation of the 3β-positions to give 7β-acetoxy-3β-hydroxy-ent-kaur-16-en-19-oic acid (14), followed by a 2β- or 18-hydroxylation of this metabolite. The incubation of epicandicandiol 7β-monoacetate (7β-acetoxy-18-hydroxy-ent-kaur-16-ene) (10) produces also the 19-hydroxylation to form the 18,19 diol (20), which is oxidized to give the corresponding C-18 or C-19 acids. These results indicated that the presence of a 7β-acetoxy group does not inhibit the fungal oxidation of C-19 in 7β-acetoxy-ent-kaur-16-ene, but avoids the ring B contraction that leads to the gibberellins and the 6β-hydroxylation necessary for the formation of seco-ring B ent-kaurenoids. The biotransformation of 7β-acetoxy-ent-trachylobane (trachinol acetate) (27) only led to the formation of 7β-acetoxy-18-hydroxy-ent-trachylobane (33).     

Diterpenoids from Sideritis arborescens subsp. Paulii

Several ent-labda-13(16),14-dienes, ent-13-epi-manoyl oxides and the new natural products ent-6α,8α-dihydroxylabda-13(16),14-diene, ent-18-hydroxy-15(16)peroxylabd-13-ene,ent-16,18-dihydroxymanoyl oxide, ent-13-epi-16,18-dihydroxymanoyl oxide and ent-6α16,18-trihydroxymanoyl oxide have been isolated from Sideritis arborescens subsp. paulii. The structures of these compounds have been established by spectroscopic means and chemical correlations.     

Three ent-trachylobane diterpenes from the leaf exudates of Psiadia punctulata

Three ent-trachylobane diterpenes have been isolated from the leaf exudates of Psiadia punctulata and characterised as 6α,17,19-ent-trachylobantriol; 2α,18,19-ent-trachylobantriol; and 2β,6α,18,19-ent-trachylobantetraol. The structures were determined on the basis of spectroscopic evidence.     

Structural Characterization and Biological Evaluation of 18‐Nor‐ent‐labdane Diterpenoids from Grazielia gaudichaudeana

The phytochemical investigation of Grazielia gaudichaudeana aerial parts yielded 15 compounds, including diterpenes, triterpenes, sterols and flavonoids. With exception to ent‐kaurenoic acid diterpenes, the compounds isolated are being described for the first time in this species. Some unusual ¹H‐NMR chemical shifts of 18‐nor‐ent‐labdane ( 7 – 9 ) led us carry out a conformational analysis by theoretical calculations in order to support the experimental data. Moreover, due to the limitation of studies focused on pharmacological potential of Grazielia gaudichaudeana, the present study was carried out to investigate the antioxidant, antiproliferative, antiviral, antileishmanial and antimicrobial activities from the extract, fractions and isolated compounds obtained from this species. Ethyl acetate fraction showed significant activity in the antiproliferative assay, with GI₅₀ range of 3.9 to 27.2 μg mL^?1. Dichloromethane fraction, rich in diterpenoids, inhibited all human tumor cell lines tested, and the nor‐labdane 7 showed potent cytotoxic activity against glioma and ovary cancer cell lines.     

Three new triterpenes from the lichen Xanthoria resendei

The three new migrated hopene type triterpenes 12α-acetoxy-3β-hydroxyfern-9(11)-ene, 3β,12α-dihydroxyfern-9(11)-ene and 3,12-diketofern-9(11)-ene have been isolated from the ether extracts of the lichen Xanthoria resendei, together with peroxyergosterol and the anthraquinone pigments physcion, fallacinal and fallacinol.     

Diterpenes from sideritis nutans

Four new ent-labdane oxide diterpenes, sidnutol, gomerol, 13-epi-gomerol and 3α-hydroxy-gomeric acid, and the previously known gomeraldehyde, 13-epi-gomeraldehyde, ent-norambreinolide, ent-2α-hydroxy-13-epi-manoyloxide, gomeric acid and 13-epi-gomeric acid, have been isolated from the aerial parts of Siderius nutans.