Phytoecdysteroids: biological aspects

Phytoecdysteroids are a family of about 200 plant steroids related in structure to the invertebrate steroid hormone 20-hydroxyecdysone. Typically, they are C27, C28 or C29 compounds possessing a 14alpha-hydroxy-7-en-6-one chromophore and A/B-cis ring fusion (5beta-H). In the present review, the distribution, biosynthesis, biological significance and potential applications of phytoecdysteroids are summarised.     

Phytoecdysteroids and glycoceramides from Eriophyton wallchii

Two new compounds, 28-epi-cyasterone and eriophytonoide, along with 11 known compounds, cyasterone, ajuforrestins A and B, 20-hydroxyecdysone, polypodin B, ajugalactone, 8-O-acetylharpagid, apigenin, N-[2hydroxy-(nonadecanoyl-tricosanoyl)]-4-hydroxy-trans-8-sphingenine, beta-sitosterol, and daucosterol, were isolated from the aqueous ethanolic extract of the whole herb of Eriophyton wallchii Benth. The structures of 28-epi-cyasterone and eriophytonoide were elucidated as (22R,24S,25S,28S)-5beta-stigmast-7-en-26-oic acid, 2beta,3beta,14,20,22,28-hexa hydroxy-6-oxo-gamma-lactone, and 1-O-beta-d-glucopyranosyl-(2S,3S,4R,8E)-2-[(2R)-2-hydroxyhexadecanoylamino]-1,3,4-octadecanetriol-8-ene, respectively, on the basis of spectral and chemical evidence.     

Phytoecdysteroids of Serratula centauroides Herb from Cisbaikalia

Russian Journal of Bioorganic Chemistry - Serratula centauroides L. is a plant species of the Asteraceae family common in Cisbaiklia and containing phytoecdysteroids. As a result of chromatographic...     

Analysis of insecticidal Azadirachta indica A. Juss. fractions

As a result of chemical investigation on the ethanolic extract of fresh fruit coatings of Azadirachta indica A. Juss. (neem), twenty-seven compounds were identified in non-polar to less polar fractions which showed pesticidal activity determined by WHO method against Anopheles stephensi Liston. These identifications were basically made through GC-EIMS and were further supported by other spectroscopic techniques, including 13C NMR, UV and FTIR as well as retention indices. Thus sixteen n-alkanes, 1-16; three aromatics 2,6-bis-(1,1-dimethylethyl)-4-methyl phenol (17), 2-(phenylmethylene)-octanal (20), 1,2,4-trimethoxy-5-(1Z-propenyl)-benzene (27); three benzopyranoids 3,4-dihydro-4,4,5,8-tetramethylcoumarin (18), 3,4-dihydro-4,4,7,8-tetramethylcoumarin-6-ol (19), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[g]-2-benzopyran (22); one sesquiterpene methyl-3,7,11-trimethyl-2E,6E,10-dodecatrienoate (21); three esters of fatty acids methyl 14-methyl-pentadecanoate (23), ethyl hexadecanoate (24), ethyl 9Z-octadecenoate (25) and one monoterpene 3,7-dimethyl-1-octen-7-ol (26) were identified. Except 6, 8, 24 and 25 all these compounds were identified for the first time from the pericarp and fifteen of these, 1-3, 7, 9, 10, 17-23, 26, 27, are hitherto unreported previously from any part of the tree. Although this tree is a rich source of various natural products, it is the first report of identification of mono- and sesquiterpenes 26 and 21 and a potent antioxidant, 17.     

Stem anatomy of Caryophyllaceae

The xylem and phloem of 88 Caryophyllaceae from subtropical and temperate regions mainly in Western Europe and the Canary Islands are described and analysed. They are compared with their taxonomic classification, and assigned to their ecological range. The xylem of different life forms (herbaceous plants, dwarf shrubs and shrubs) consists mainly of parenchyma and small vessels that are 20–50 μm in diameter in earlywood. They have simple perforations and pits are pseudosclariform and scalariform. The axial parenchyma is mostly pervasive or paratracheal, and the ray cells are exclusively upright or square. The anatomy of the subfamily Alsinoideae is homogeneous and characterised by the absence of libriform fibres, large rays, crystal druses and sclereids in the cortex. The subfamily Caryophylloideae is less homogeneous and mainly characterised by the presence of crystal druses on the xylem and phloem, as well as the presence of intra-annual fibre bands. The subfamily Paronychioideae is heterogeneous; included phloem is most characteristic. Ecological trends are clearly expressed by the age of plants and the average annual radial growth rates. Plants tend to grow older and slower at higher altitudes. The presence of intra-annual fibre bands in the xylem is characteristic of Caryophylloideae at lower altitudes. The study suggests that taxonomic and ecological classifications and large-scale ecological trend studies must be based on large and homogeneous datasets and well-defined anatomical features.     

Phytoecdysteroids from the rhizomes of Brainea insignis

Phytoecdysteroid glucosides, brainesterosides A–E, were isolated from the rhizomes of Brainea insignis along with three known phytoecdysteroids, ponasteroside A, ponasterone A, and 20-hydroxyecdysone. Their structures were elucidated by spectroscopic and chemical means. A possible biogenetic pathway is postulated for these compounds. The chemosystematic significance of ponasterone A is discussed.     

三种北极石竹科植物中的环肽及石竹科环肽的化学分类和分布意义

用HPLC等现代分离技术,从各样少于100g的北极3种石竹科(Caryophyllaceae)植物StellariacrassipesHult.、CerastiumarcticumLange和C.regeliiOstenf.中分得5个新环肽,分别命名为arcticuminA(1)、arcticuminB(2)、arcticuminC(3)、regelinA(4)和crassipinB(5),并通过FAB -MS和氨基酸组成分析初步鉴定了它们的结构;通过对北极石竹科环肽与青藏高原石竹科环肽的比较,证明了环肽是石竹科的特征成分以及北极地区是石竹科植物分布中心的一个区域。     

Petrorhagia grandiflora sp. nov. (Caryophyllaceae) from Greece

Petrorhagia grandiflora Iatroú sp. nov. is described from limestone rocks on the eastern side of Mt. Parnon, in the province of Arkadhia, Peloponesos, Greece. This species, belonging to sect. Petrorhagia subsect. Thessalae Ball & Heywood, is related to the P. thessala (Boiss.) Ball & Heywood and P. dianthoides (Smith) Ball & Heywood with which it is compared. Chromosome numbers (2n = 30) and karyotypes are presented; seeds are examined by a Scanning Electron Microscope (SEM); and their distribution in Greece are presented.     

Hybridization studies inSilene subgen.Petrocoptis (Caryophyllaceae)

Silene subgenusPetrocoptis comprises sexual diploid taxa and it is restricted to calcareous cliffs in the Iberian peninsula. Artificial crosses involvingSilene pyrenaica (Bergeret)Mayol etRosselló (≡Petrocoptis pyrenaica (Bergeret)Walp.),Silene laxipruinosa Mayol etRosselló andS. montserratii subsp.crassifolia (Rouy)Mayol etRosselló (≡P. crassifolia Rouy) were attempted to assess the extent of barriers developed within the subgenusPetrocoptis. Usually, intraspecific crosses involving allopatric populations were successful, suggesting that geographically isolated populations are not genetically isolated. Cross-compatibility was noted among the polymorphicS. pyrenaica, which developed fertile F₁ hybrids. All other interspecific crosses failed due to cross- or seed-incompatibility. Crossing results agree with available evidence supporting the merging of segregates ofS. pyrenaica within a single taxon.     

Molecular Phylogenetic Analysis of Petunia Juss. (Solanaceae)

Representatives from 11 Petunia Jussieu species in south and southeast Brazil were compared with two Calibrachoa La Llave & Lex., one Bouchetia Dunal, and two Nierembergia Ruiz & Pav. taxa in relation to DNA molecular variability. A total of 4532 base pairs related to one nuclear, five plastidial and one mitochondrial systems was investigated. Petunia and Calibrachoa, although separated among themselves, clearly differentiate from the two other genera. Despite the fact that the Petunia species do not show marked molecular differences, they can be separated in two complexes, in good agreement with altitude data. Petunia + Calibrachoa should have diverged from other clades at about 25 million years before present.     

Typification of Cerastium fontanum ssp. vulgare (Caryophyllaceae)

The basionym of Cerustium fontanum ssp. vulgare (Hartman) Greuter and Burdet, C. vulgare Hartman, is neotypified, based on a specimen in UPS. Flora Nordica notes No. 14.     

Bufonia yildirimhanii sp. nov. (Caryophyllaceae) from Turkey

Bufonia yildirimhanii?lçim & Behçet sp. nov. (Caryophyllaceae) is described and illustrated from Turkey. This new species is confined to C7 Sanl?urfa‐Birecik where it grows on calcarous slopes. The species is compared with the closely related Bufonia calyculata and B. kotschyana subsp. kotschyana. Notes on its ecology and conservation status are provided. A distribution map of the new and related species is also included.     

Phytoecdysteroids in the genus Asparagus (Asparagaceae)

Phytoecdysteroids, plant steroids which are analogues of invertebrate steroid hormones, probably contribute to the deterrence of phytophagous invertebrate predators. They also seem to possess antimicrobial activity and several pharmaceutical and medicinal benefits have been ascribed to them. Here. we present a survey of seeds of 16 species of the genus Asparagus (Asparagaceae), including the crop species A. officinalis, for ecdysteroid agonists (including phytoecdysteroids) and antagonists. Seven species were found to contain ecdysteroids with levels ranging from just detectable (A. racemosus and A. sarmentosus) to relatively high (A. laricinus). RP-HPLC/RIA/bioassay has been used to separate positive extracts of four species (A. falcatus, A. laricinus, A. ramosissimus and A. scandens) and analyse the ecdysteroid profiles. The identities of the major ecdysteroids were confirmed by NP-HPLC. Seeds of A. officinalis do not contain detectable levels of ecdysteroids, but leaves, stems and roots contain low levels (detectable by RIA). This indicates that A. officinalis retains the genetic capacity to synthesise ecdysteroids and that future strategies could be developed for enhanced protection of asparagus spears through elevated ecdysteroid levels.     

Somatic embryogenesis and plant regeneration inAzadirachta indica A. Juss

Summary Media for induction of somatic embryogenesis from immature cotyledonary tissues ofAzadirachta indica (Neem) were determined. Callus was initiated on Murashige and Skoog medium supplemented with 0.5 mg·liter⁻¹ of indol-3 acetic acid, 1.0 mg·liter⁻¹ of 6-benzyl amino purine, and 1000 mg·liter⁻¹ of casein hydrolysate. Effect of kinetin was also studied for embryo induction. Carbohydrate source in the form of sucrose and glucose alone and in combination was tested for embryogenic efficiency. Seventy percent embryos showed germination. Healthy plants were potted in sand and soil. Histologic studies confirmed indirect somatic embryogenesis.     

On the races of Arenaria tetraquetra L. (Caryophyllaceae)

FAVARGER, C. & NIETO FELINER, G., 1988 On the races of Arenoria tetraquetra L. (Caryophyllaceae). The caryological study of some Betic populations of Arenaria tetraquetra northwards from Sierra Nevada has proved that they are polyploids ( 3x, 4x, 5x ). Even though their Rowers are pentamerous, they differ from the Nevadean Arenaria tetraguetra subsp. amabilis (2x ) not only by the chromosome number but also by the micromorphology of the seed coat and the hairiness of the stem internodes. They also differ from Arenaria tetraquetra subsp. tetraquetra , the Rowers of which are tetramerous and the degree of polyploidy higher (6x in the Pyrenees, 7x in the Sierra de Pela eastwards from Sierra de Guadarrama). The authors proposed to give a subspecific status to such Betic polyploid populations with a new combination. They suggest a hypothesis to explain the evolution of the A. tetraguetra polyploid complex.     

Phytoecdysteroids in seeds of Lloydia serotina (Liliaceae)

Seeds of a number of species in the Liliaceae (sensu Brummitt, 1992) were examined for the presence of ecdysteroid agonist and antagonist activities. No species were antagonistic to 20-hydroxyecdysone action on the ecdysteroid-responsive Drosophila melanogaster B_II cell line and only one extract, that of Lloydia serotina, was agonistic. This activity is attributable to the presence of phytoecdysteroids as detected by ecdysteroid-specific radioimmunoassay and the agonist version of the B_II bioassay. HPLC in conjunction with radioimmunoassay and bioassay have been used to determine the ecdysteroid profile. The major ecdysteroids present are identified as 20-hydroxyecdysone and polypodine B (5β,20-dihydroxyecdysone).     

Sagina rupestris sp. nov. (Caryophyllaceae) from New Guinea

A new species, Sagina rupestris , endemic to Mt. Suckling, Papua New Guinea is described and illustrated.     

Distribution of phytoecdysteroids in the Caryophyllaceae

Certain genera within the Caryophyllaceae (especially Silene and Lychnis) have received a significant amount of attention with regard to the isolation and identification of ecdysteroids. However, the taxonomy of this family is difficult. Hence, the occurrence of phytoecdysteroids in members of the Caryophyllaceae is presented, and combined with new data on ecdysteroid agonist (phytoecdysteroid) and antagonist activities, in order to survey the distribution of phytoecdysteroid-containing species within this large family, and to assess the utility of phytoecdysteroids as chemotaxonomic markers. The new data presented (representing ca. 110 species) have been obtained by the application of sensitive biological/biochemical methods for the detection of ecdysteroid agonists and antagonists, using Drosophila melanogaster B(II) bioassay and ecdysteroid-specific immunoassays. In the antagonist version of the B(II) bioassay, only weak ecdysteroid antagonist activities were detected in a few of the extracts. From both new and previously available data, it was found that phytoecdysteroids were present predominantly in the Genera Lychnis, Petrocoptis, Sagina and Silene. Comparison of ecdysteroid occurrence with a molecular phylogeny for the tribe Sileneae [Taxon 44 (1995) 525] revealed close association of ecdysteroid occurrence with certain groups of this tribe. In 14 species of Silene examined, there is a reasonable, but not absolute, relationship between the presence of ecdysteroids in the seeds and in other plant parts. Where ecdysteroids are present in the plant, highest concentrations are generally present in the roots.