Zur biogenese von strophanthidin-glykosiden: Convallatoxol als vorstufe von convallatoxin in Convallaria majalis

Labelled convallatoxin was isolated from leaves of Convallaria majalis after administration of convallatoxol-19-³H and convallatoxol-U-¹⁴C, resp. Oxidation of-CH₂OH → -CHO at the glycoside level therefore is a possible step in the biogenesis of strophanthidin glycosides.     

Interaction of External K, Na, and Cardioactive Steroids with the Na-K Pump of the Human Red Blood Cell

The interaction of extracellular Na (Na_o), K (K_o), and strophanthidin with the Na-K pump of the human red blood cell has been investigated. Inhibition by submaximal concentrations of strophanthidin rapidly reaches a level which does not increase further over a relatively long period of time. Under these circumstances, it is possible to apply a steady-state kinetic analysis to the interaction of Na_o, K_o, and strophanthidin with the pump. In Na-free solutions, strophanthidin increases the apparent K_1/2 of the pump for K_o, but does not change the form of the relation between the reciprocal of the active K influx (ⁱM_K^P–1) and the reciprocal of [K_o] ([K_o]^–1); the relation both in the presence and absence of strophanthidin is adequately described by a straight line. In solutions containing Na, strophanthidin changes the form of the curve describing the relation between ⁱM_K^P–1 vs. [K_o]^–1; the curve becomes more parabolic in solutions containing strophanthidin. The rate of ouabain binding to K-free cells has also been measured; in the absence of K, the rate of binding is unaffected by Na_o. The data are considered in terms of a simple kinetic model. The findings can be explained if it is supposed that at low external K the form of the pump combined with one Na_o is more likely to combine with strophanthidin than is the uncombined form of the pump. The uncombined form of the pump is more likely to combine with K even at very low K_o than with strophanthidin.     

Structure-activity relationships of several cardiotonic steroids with respect to inhibition of ion transport in frog muscle

Cesium uptake by sodium-loaded frog sartorius muscles was inhibited 100% by 10^-6 M ouabain and 10^-6 M cymarin. The doses for 50% inhibition of cesium uptake by five cardiotonic aglycones were 1.5 x 10^-6 M for strophanthidin, 2 x 10^-7 M for telocinobufagin, 1.6 x 10^-6 for digitoxigenin, 2.4 x 10^-6 M for periplogenin, and 6.3 x 10^-6 M for uzarigenin. Because of the limited solubility of sarmentogenin the maximum concentration studied was 2 x 10^-6 M which inhibited cesium uptake about 36%. Inhibition of cesium uptake by cymarin was not reversed during a 3.5 hr incubation in fresh solution while the muscles treated with ouabain and strophanthidin recovered partly during this time. Cymarin was a more potent inhibitor of sodium efflux than strophanthidin and periplogenin was less potent. Increased cesium ion concentration in the external solution decreased the strophanthidin inhibition of cesium uptake but 25 mM cesium did not overcome the inhibition by 10^-8-10^-6 M strophanthidin. Increased potassium ion concentration in the external solution decreased but did not completely overcome inhibition of sodium efflux by strophanthidin. It is concluded that potassium or cesium ions do not compete with these drugs for a particular site on the ion transport complex. The same structural features of the drugs are necessary for inhibition of ion transport in frog muscle as are required for inhibition of ion transport in other tissues, inhibition of sodium-potassium-stimulated ATPases, and toxicity to animals.     

A leptosidin glycoside from leaves of Cyperus scariosus

Phytochemical examination of the leaves of Cyperus scariosus resulted in the isolation and identification of a new glycoside, leptosidin 6-O-β-d-glucopyranosyl-O-α-l- rhamnopyranoside.     

Monoterpenoid glycoside derivatives from Melaleuca alternifolia

The phytochemical investigation of leaves of Melaleuca alternifolia (Maiden & Betche) Cheel led to the isolation of a new monoterpenoid glycoside derivative melaleuoside (1), together with four known monoterpenoid glycoside derivatives (2–5). Structure elucidation of these compounds was performed based on NMR spectral data and MS. Compounds 2–5 were isolated from the genus of Melaleuca for the first time. Furthermore, we also discussed the chemotaxonomic significance of the isolates in this thesis.     

Catalpol and methylcatalpol: naturally occurring glycosides in Plantago and Buddleia species

1. A glycoside of the aucubin type has been isolated in crystalline form from Plantago and Buddleia species, and has been shown to be identical with catalpol (Lunn, Edward & Edward, 1962). Catalpol has not been found in the free state before, but occurs as its p-hydroxybenzoyl ester, catalposide, in the genus Catalpa. 2. A second glycoside of this type has been obtained in crystalline form from Buddleia, and has been shown to be a mono-O-methyl derivative of catalpol, for which the name `methylcatalpol' is proposed. 3. Both Plantago and Buddleia species are known to contain aucubin. The concentrations of this glycoside and catalpol are comparable in Plantago. In Buddleia methylcatalpol predominates somewhat over catalpol. Yields of the individual glycosides were about 0·1% of the fresh weight of the leaves. 4. Bobbitt, Spiggle, Mahboob, Philipsborn & Schmid (1962) have suggested structures for catalposide and catalpol based on chemical and physical evidence, in particular on n.m.r. spectra. Reappraisal of this evidence and additional measurements have now confirmed these structures and show that the Buddleia glycoside is the 6-O-methyl derivative of catalpol.     

Humans and other animals and the plants they ingest

Primula allionii is endemic to a tiny area of the Maritime Alps and has one of the narrowest distribution ranges in this hotspot of biodiversity. Phylogeographical patterns in P. allionii were studied using plastid DNA markers and dominantly inherited markers (AFLP and ISSR) to verify any admixture between P. allionii and the sympatric P. marginata and to detect the phylogeographical history of the species. Morphometric measurements of flowers and admixture analysis support the hypothesis that hybridization occurs in nature. Species distribution models using two climate models (CCSM and MIROC) suggested a reduction in habitat suitability during cold periods. Phylogeographical analysis suggested an old allopatric divergence during the mid‐Pleistocene transition (about 0.8 Mya) without recolonization/contraction cycles. The Alps watershed does not act as a strong barrier between the two main areas of the distribution range, and moderate gene flow by pollen seems to create the admixture recorded among the stands. According to our results, the persistence of P. allionii throughout the Ice Age appears to be linked to the capacity of the Maritime Alps to provide a wide diversity of microhabitats consistent with the recent biogeographical pattern proposed for the Mediterranean Basin. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 637–653.     

Les flavonoides des feuilles du Phragmites australis: essai de définition du profil polyphénolique de l'espéce

Four flavonol glycosides, one flavone glycoside and six C-glyosylflavones have been identified in the leaves of Phragmites australis. Among the latter is 7,3′-dimethylisoorientin, which has only been reported once before in nature.     

Monoterpene and lignan glycosides in the leaves of Crataegus pinnatifida

In the present phytochemical study on the leaves of Crataegus pinnatifida, a new monoterpene glycoside, (3S,5R,6R,7E,9R)-3,6-epoxy-7-megastigmen-5,9-diol-9-O-β-Dglucopyranoside(6) and a new sesquilignan glycoside, acernikol-4’’-O-β-D-glucopyranoside (15), together with thirteen known compounds were isolated.     

Shading Influence on the Sterol Balance of Nicotiana tabacum L

Tobacco plants (Nicotiana tabacum L.) were grown in the field and the apex was removed at the 42-day stage. Shading screens were set up which produced 0, 26, 67, and 90% shade. Plants were grown an additional 25 days before leaves from top, middle, and bottom stalk positions were harvested. Each leaf group was analyzed for free sterol, steryl ester, steryl glycoside, and acylsteryl glycoside. The free sterol content was lowest in top leaves and highest in bottom leaves; however, the top leaves had more steryl ester than the bottom leaves. Leaf position had no effect on steryl glycosides and acylsteryl glycosides. Shading did not influence the level of any sterol class; but in general, shading increased stigmasterol and decreased sitosterol. This trend was observed for all sterol classes, and the free sterols showed the largest and most consistent change. The younger top leaves showed a greater response than the older bottom leaves, but bottom leaves always had more stigmasterol than sitosterol even without shade.     

Effects of genotype,habitat, and seasonal variation on iridoid glycoside content of Plantago lanceolata (Plantaginaceae) and the implications for insect herbivores

Summary We investigated the effects of genotype, habitat, and seasonal variation on production of the iridoid glycosides, aucubin and catalpol, in leaves of the common weed Plantago lanceolata. Two genotypes, one each from a lawn and an adjacent abandoned hayfield population, were clonally replicated in the greenhouse, and then planted back into the two habitats. One quarter of the plants from each treatment were harvested on each of four dates, at approximately two-week intervals. Over the course of the growing season, and in both habitats, we found a significant increase in the concentration of both aucubin and catalpol in P. lanceolata leaves. The genotypes differed in their response to environmental variation, both in time and between sites, as indicated by significant genotype x date and genotype x site interactions. Early in the season, habitat (lawn or field) had a greater effect on iridoid glycoside concentration than did plant genotype, but later in the season, plant genotype was more influential in determining the iridoid glycoside concentration. Thus, the relative palatability of Plantago genotypes to specialist and generalist herbivores may vary in time and space.     

β-glucosyl esters of 19α-hydroxyursolic acid derivatives in leaves of Rubus species

β-Glucosyl esters of A-ring oxygenated 19α-hydroxyursolic acids were isolated from the leaves of Rubus microphyllus, R. koehneanus, R. trifidus and R. medius. Comparisons of the glycoside fractions of the leaves of 39 Rubus species were conducted, indicating the chemotaxonomic significance of this type of glucosyl ester in this genus.     

Quadranguloside,a cycloartane triterpene glycoside from Passiflora quadrangularis

Quadranguloside, a new cyclopropane triterpene glycoside was isolated from the methanolic extract of the leaves of Passiflora quadrangularis. Its structure has been established as 9,19-cyclolanost-24Z-en-3β,21,26-triol-3,26-di-O-gentiobioside on the basis of hydrolysis and spectral evidence.     

Cyanogenesis in Acacia sutherlandii

Two cyano-glucosides have been isolated from leaves of Acacia sutherlandii. One is the previously described cyanogenic glucoside proacacipetalin and the other is the novel, non-cyanogenic, glycoside 1-cyano-2-β-D-glucopyranosyloxymethyl-(Z)-prop-1-en-3-ol which has been given the trivial name sutherlandin.     

One new flavonoid xyloside and one new natural triterpene rhamnoside from the leaves of Syzygium grande

One new flavonoid glycoside, myricetin 4′-methyl ether 3-O-β-d-xylopyranoside (1) and one new natural triterpene glycoside, grandoside (2) were isolated from a MeOH extract of the leaves of Syzygium grande, together with thirteen known compounds (3–15). The structures of the new compounds were determined through a combination of spectroscopic and chemical analyses. All of the isolated compounds were evaluated for their antifungal, antibacterial, anti-leishmania, DPPH radical-scavenging and cytotoxic activities by means of MTT assay.     

Quercetin coumaroyl glucorhamnoside from Ginkgo biloba

A new flavonoid glycoside was isolated from the leaves of Ginkgo biloba (Ginkgoaceae) and its structure elucidated as quercetin-3-O-α-(6‴-p-coumaroylglucosyl-β-1,4-rhamnoside).     

Havanine—a steroidal alkaloid glycoside from Solanum havanense

A new steroidal alkaloid glycoside named havanine has been isolated from the leaves of Solanum havanense and its structure elucidated by spectral data as (25S)-O(3)-β-D-glucopyranosyl-16α-acetoxy-22,26-epiminocholesta-5,22(N)-dien-3β-ol.     

Hamamelose and its derivatives as chemotaxonomic markers in the genus Primula

About 550 species of vascular plants as well as a few mosses were checked for the occurrence of hamamelose, the corresponding alcohol hamamelitol and a galactoside of the latter, clusianose. Hamamelose was found in most of the species investigated. It provides therefore no useful character for chemotaxonomic purposes. Hamamelitol, however, could only be detected in the genus Primula and was therefore more useful. Small amounts of hamamelitol were found in the leaves of species from the subgenera Auganthus, Aleuritia and Auricula but not from Primula and Sphondylia. Clusianose and large amounts of hamamelitol are produced by species of 4 subsections of the section Auricula, but not by species of the subsections Auricula and Erythrodrosum. A taxonomic separation of the two latter from the 4 former subsections is suggested. The taxonomic position of Primula allionii should be reconsidered, since neither clusianose nor hamamelitol could be demonstrated in this species, whereas the other species of the subsection Rhopsidium do contain these carbohydrates.     

Fractionation of Sodium Efflux in Frog Sartorius Muscles by Strophanthidin and Removal of External Sodium

The influence of strophanthidin, ouabain, and the removal of external sodium on the sodium efflux from frog sartorius muscle was measured. In freshly dissected muscles strophanthidin and ouabain in maximally effective concentrations reduced the efflux of sodium by about 50%. Of the sodium efflux which is strophanthidin-insensitive about 75% is inhibited after complete replacement of external sodium by lithium. In the absence of strophanthidin replacement of external sodium by lithium, calcium, or magnesium produces an initial rise in the sodium efflux, followed by a fall in the efflux as the exposure of the muscles to sodium-free media is continued. When the muscles are exposed for prolonged periods in sodium-free media, the fraction of internal sodium lost per minute is higher when returned to normal Ringer fluid than it was initially. The activation of sodium efflux by external sodium after long periods in sodium-free solutions is partly strophanthidin-sensitive and partly strophanthidin-insensitive. The internal sodium concentration is an important factor in these effects. The effects of temperature on the sodium efflux were also measured. Above 7°C the Q₁₀ of both the strophanthidin-sensitive and strophanthidin-insensitive sodium efflux is about 2.0. Below 7°C the strophanthidin-insensitive sodium efflux has a Q₁₀ of about 7.4.