Diterpenoids from Sideritis foetens

From the aerial parts of Sideritis foetens, the previously known ent-13(16),14-labdadiene-6α,8α,18-triol (andalusol) has been isolated. In addition, two new natural andalusol monoacetates and the novel ent-6α-acetoxy-13(16),14-labdadiene-3β,8α-diol have also been obtained from the same source. The structures of these new diterpenoids have been established by chemical and spectroscopic means.     

Four new diterpenes from Sideritis serrata

Four new diterpenes have been isolated from Sideritis serata: lagascol (4, ent-8,5-friedopimar-5-ene-15S,16-diol), tobarrol (8, ent-15-beyerene-12α,17-diol), benuol (12, ent-15-beyerene-7α,17-diol) and serradiol (18, ent-16R-atis-13-ene-16,17-diol). The previously known diterpenes lagascatriol (1, ent-8,5-friedopimar-5-ene-11β,15S,16-triol), jativatriol (2, ent-15-beyerene-1β,12α,17-triol), conchitriol (3, ent-15-beyerene-7α,12α,17-triol) and sideritol (17, ent-16R-atis-13-ene-1β,16,17-triol) have also been obtained from the same source.     

Polyoxygenated ent-kauranes and water-soluble conjugates in seed of Phaseolus coccineus

C-α and C-β, previously isolated from seed of Phaseolus coccineus, are shown respectively to be the bis-O-isopropylidene and the 16,17-mono-O-isopropylidene derivatives of ent-6α,7α,16β,17-tetrahydroxykauranoic acid. By GC-MS characterization of the products of acidic, basic and enzymatic hydrolysis, water soluble conjugates of the following compounds have been shown to occur in P. coccineus seed: GA₈, GA₁₇, GA₂₀, GA₂₈, ent-6α,7α,13-trihydroxykaurenoic acid, ent-6α,7α,17-trihydroxy-16β-kauranoic acid, ent-6α,7α,16β,17-tetrahydroxykauranoic acid, 7β,13-dihydroxykaurenolide and abscisic acid.     

GC/MS analysis of the plant hormones in seeds of Cucurbita maxima

The GC/MS detection is reported of over 30 compounds, in extracts of the endosperm and embryos from seeds of Cucurbita maxima. The compounds which were identified from reference spectra include: cis,trans-ABA; trans,trans-ABA; dihydrophaseic acid; IAA; GA₄; GA₁₂; GA₁₃; GA₂₅; GA₃₉; GA₄₃; GA₄₉; ent-13-hydroxy-, ent-6α,7α-and ent-7α,13-dihydroxy-, and ent-6α,7α,13-trihydroxykaur-16-en-19-oic acids; ent-7α,16,17-trihydroxy- and ent-6α,7α,16,17-tetrahydroxy-kauran-19-oic acids, ent-6,7-seco-7-oxokauren-6,19-dioic acid and/or ent-6,7-secokauren-6,7,19-trioic acid, and 7β,12α-dihydroxykaurenolide. New compounds, the structures of which were deduced from GC/MS data, include: the 12α-hydroxy-derivatives of GA₁₂, GA₁₄, GA₃₇ and GA₄, and the 12β-hydroxy-derivatives of ent-7α-hydroxy- and ent-6α,7α-dihydroxykaurenoic acids.     

Ent-kauren-19-oic acid derivatives from the stem bark of Croton pseudopulchellus Pax

Two new ent-kauren-19-oic acid derivatives, ent-14S*-hydroxykaur-16-en-19-oic acid and ent-14S*,17-dihydroxykaur-15-en-19-oic acid together with eleven known compounds ent-kaur-16-en-19-oic acid, ent-kaur-16-en-19-al, ent-12β-hydroxykaur-16-en-19-oic acid, ent-12β-acetoxykaur-16-en-19-oic acid, 8R,13R-epoxylabd-14-ene, eudesm-4(15)-ene-1β,6α-diol, (?)-7-epivaleran-4-one, germacra-4(15), 5E,10(14)-trien-9β-ol, acetyl aleuritolic acid, β-amyrin, and stigmasterol were isolated from the stem bark of Croton pseudopulchellus (Euphorbiaceae). Structures were determined using spectroscopic techniques. Ent-14S*-hydroxykaur-16-en-19-oic acid, ent-kaur-16-en-19-oic acid, ent-12β-hydroxykaur-16-en-19-oic acid, ent-12β-acetoxykaur-16-en-19-oic acid and 8R,13R-epoxylabd-14-ene were tested for their effects on Semliki Forest virus replication and for cytotoxicity against human liver tumour cells (Huh-7 strain) but were found to be inactive. Ent-kaur-16-en-19-oic acid, the major constituent, showed weak activity against the Plasmodium falciparum (CQS) D10 strain.     

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.     

Ent-2α-hydroxy-13-epi-manoyl oxide from Sideritis perfoliata

A new ent-13-epi-manoyl oxide derivative was isolated from the aerial part of Sideritis perfoliata. Its structure, ent-2α-hydroxy-8,13β-epoxy-labd-14-ene, was established by chemical and spectroscopic means.     

The metabolism of steviol to 13-hydroxylated ent-Gibberellanes and ent-kauranes

Steviol(ent-13-hydroxykaur-16-en-19-oic acid) is rapidly metabolised by the mutant B1-41a of Gibberellafujikuroi. The initial product is the ent- 7-α-hydroxy derivative which is then further metabolised to gibberellins A₁, A₁₈, A₁₉, A₂₀, 13-hydroxy GA₁₂, the ent-6α, 7α, 13- and ent-6β, 7α, 13 (19,6-lactone)-trihydroxykaurenoic acids, and a seco-ring B diacid. This apparently low substrate specificity of the enzymes operative beyond the block in the mutant B1-41a provides a useful model for the biosynthetic pathways to 13-hydroxylated gibberellins of higher plants and a preparative route to these plant gibberellins.     

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.     

Microbial transformation of neoandrographolide by Mucor spinosus (AS 3.2450)

Microbial transformation of neoandrographolide (1), was performed by Mucor spinosus (AS 3.2450). Ten metabolites were obtained and identified as 14-deoxyandrographolide (2), 17,19-dihydroxy-8,13-ent-labdadien-16,15-olide (3), 3,14-dideoxyandrographolide (4), 7β-hydroxy-3,14-dideoxyandrographolide (5), 17,19-dihydroxy-7,13-ent-labdadien-16,15-olide (6), 8(17),13-ent-labdadien-16,15-olid-19-oic acid (7), 8α,17β-epoxy-3,14-dideoxyandrographolide (8), 8β,17,19-trihydroxy-ent-labd-13-en-16, 15-olide (9), phlogantholide-A (10), 19-[(β-d-glucopyranosyl)oxy]-19-oxo-ent-labda-8(17),13-dien-16,15-olide (11) by spectroscopic and chemical means. Among them, products 3, 5, 6, 8 and 9 were characterized as new compounds. The inhibitory effects of compounds 1–11 on nitric oxide production in lipopolysaccharide-activated macrophages were evaluated and their preliminary structure–activity relationships (SAR) were discussed.     

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.     

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.     

Ent-kaurene diterpenoids and lignan from Leontopodium leontopodioides and their inhibitory activities against cyclooxygenases-1 and 2

Two new ent-kaurene diterpenoids, 13α,15α-dihydroxy-18-carboxy-19-nor-ent-kaur-16-ene-2β-O-(2′-angelate)-β-d-glucopyranoside (leontocin A, 1), 13α,15α-dihydroxy-18-carboxy-19-nor-ent-kaur-16-ene-2β-O-(2′-angelate-6′-acetyl)-β-d-glucopyranoside (leontocin B, 2), and one new lignan, 2,3-bis[(3,4-di-hydroxyphenyl)methylene]-monoethyl ester-butanedioic acid (leontolignan A, 3), together with three known phenolic acids (4-6) were isolated from the aerial parts of Leontopodium leontopodioides (Asteraceae). Their structures were elucidated by chemical and spectroscopic methods. All isolates were evaluated for their anti-inflammatory activities by measuring their inhibitory effects against cyclooxygenase-1 and 2 in vitro.     

Gibberellin A43 and other terpenes in endosperm of Echinocystis macrocarpa

By GC-MS the following acidic constituents of the endosperm of Echinocystis macrocarpa were identified: abscisic acid and its trans,trans-isomer, 4′-dihydrophaseic acid, GA₄, GA₇, iso-GA₇, GA₂₄, GA₂₅, two isomers of GA₁₃, GA₄₃, ent-6α,7α,17-trihydroxy-16αH-kauran-19-oic acid and ent-6α,7α, 16β, 17-tetrahydroxykauran- 19-oic acid. The structures of the last three new natural products were confirmed by partial synthesis. ent-Kaurene was detected in the neutral fraction.     

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.     

Stereochemistry of strictic acid and related furano-diterpenes from conyza japonica and grangea maderaspatana

Extraction of Conyza japonica gave strictic acid, ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid and 5,7-dihydroxy-3,8,4′-trimethoxyflavone. Extraction of Grangea maderaspatana gave (-)-hardwickiic acid, ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid and 3-hydroxy-8-acetoxypentadeca-1,9,14-trien-4,6-diyne. The structure of ent-2β-hydroxy-15,16-epoxy-3,13(16),14-cleroclatrien-18-oic acid was deduced by spectroscopic methods and by partial synthesis from (-)-hardwickiic acid and the stereochemistries of strictic acid and (ent-15,16-epoxy-1,3,13(16),14-clerodatraen-18-oic acid were established by correlation with ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid.     

Two diterpene alcohols from Croton sublyratus

The isolation and structural elucidation of two diterpene alcohols from Croton sublyratus are described. These compounds are ent-3α-hydroxy-13-epimanool and ent-16β,17-dihydroxykaurane.     

The inhibition of gibberellin plant hormone biosynthesis by ent-6-hydroxy-5β(H)- 7-norgibberell-16-enes

ent-6α-Hydroxy-5β(H)-7-norgibberell-16-en-19-oic acid and the corresponding diol but not the ent-6β-epimers are shown to be inhibitors of gibberellin biosynthesis at the ring contraction stage and to be potential plant-growth regulators. Their metabolism by Gibberella fujikuroi has been examined.     

Structures of the Metabolites from Steviol Methyl Ester by Gibberella fujikuroi

Steviol methyl ester (methyl ent-13-hydroxykaur-16-en-19-oate)* was converted into five new metabolites together with a known compound, methyl ent-7α,13-dihydroxykaur-16-en-19-oate, by Gibberella fujikuroi in the presence of a plant growth retardant. The structures of these new metabolites were elucidated to be methyl ent-7β,13-dihydroxykaur-16-en-19-oate, methyl ent-11α,13-dihydroxykaur-16-en-19-oate, methyl ent-7β,11α,13-trihydroxykaur-16-en-19-oate, methyl ent-11α, 13,15β-trihydroxykaur-16-en-19-oate and methyl ent-13,15β-dihydroxy-11-oxokaur-16-en-19-oate mainly by spectroscopic analyses.     

Diterpenoids and a sesquiterpene lactone from viguiera ladibractate

Eight known diterpene acids, ent-12-oxokaur-9(11),16-dien-19-oic acid, ent-12β-hydroxykaur-9(11),16-dien-19-oic acid, ent-isokaur-15(16)-en-17,19-dioic acid, ent-15α,16-epoxy-17-hydroxykaura-19-oic acid, ent-kaura-17,19-dioic acid, ent-kaur-16-en-19-oic acid, grandifloric acid, angeloyloxygrandifloric acid, as well as a new sesquiterpene lactone, ladibranolide, were isolated from Viguiera ladibractate. The stereochemistry of the sesquiterpene lactone was established by NOE experiments.