Bio-Based Aromatic Epoxy Monomers for Thermoset Materials.

The synthesis of polymers from renewable resources is a burning issue that is actively investigated. Polyepoxide networks constitute a major class of thermosetting polymers and are extensively used as coatings, electronic materials, adhesives. Owing to their outstanding mechanical and electrical properties, chemical resistance, adhesion, and minimal shrinkage after curing, they are used in structural applications as well. Most of these thermosets are industrially manufactured from bisphenol A (BPA), a substance that was initially synthesized as a chemical estrogen. The awareness on BPA toxicity combined with the limited availability and volatile cost of fossil resources and the non-recyclability of thermosets implies necessary changes in the field of epoxy networks. Thus, substitution of BPA has witnessed an increasing number of studies both from the academic and industrial sides. This review proposes to give an overview of the reported aromatic multifunctional epoxide building blocks synthesized from biomass or from molecules that could be obtained from transformed biomass. After a reminder of the main glycidylation routes and mechanisms and the recent knowledge on BPA toxicity and legal issues, this review will provide a brief description of the main natural sources of aromatic molecules. The different epoxy prepolymers will then be organized from simple, mono-aromatic di-epoxy, to mono-aromatic poly-epoxy, to di-aromatic di-epoxy compounds, and finally to derivatives possessing numerous aromatic rings and epoxy groups.

Isolation of marinobufotoxin from the supernatant of cultured PC12 cells.

1. Digitalis-like factors (DLFs) are believed to be involved in sodium metabolism via inhibition of Na(+) /K(+) -ATPase and may cause hypertension. Yet, the source and regulation of secretion of DLFs remain unknown. Recently, marinobufagenin (MBG) was isolated in mammals and implicated in renal sodium and water metabolism. More recently, we isolated marinobufotoxin (MBT), a suberoyl arginine ester of MBG, in Y-1 cells. We have developed an ELISA to measure MBG-like immunoreactivity (MBG-IR) and have characterized MBG-IR using chromatography. We have also identified a ouabain-like factor in cultured PC12 cells from a phaeochromocytoma cell line. In the present study, we examined whether MBT was produced in the adrenal medulla. 2. PC12 cells were cultured in serum-free medium and culture supernatants were collected over a period of 24 h. The supernatants were analysed by ELISA and HPLC to determine MBG-IR content. The HPLC fraction containing the main peak of MBG-IR was characterized by LC/MS. 3. Compared with samples collected at 0.5 h, the concentration of MBG-IR in culture supernatants increased significantly after 2 h and continued to increase until 24 h. The fraction with the highest ELISA peak for MBG-IR had the same HPLC elution time as authentic MBT. Furthermore, tandem mass spectrometry indicated that each fraction of MBT and MBG had the correct specific daughter ions. 4. The results indicate that MBT and MBG are produced and/or secreted by adrenomedullary cells.

Analyses of biologically active steroids: antitumor active OSW-1 and cardiotonic marinobufotoxin, by matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight tandem mass spectrometry.

Naturally occurring constituents of biological or pharmaceutical interest often exist in the form of glycosides or conjugates. Mass spectral investigations of these compounds require soft ionization techniques if information on molecular mass, sugar sequence, or conjugate content is desired. In this study, matrix-assisted laser desorption/ionization (MALDI) quadrupole ion trap (QIT) time-of-flight tandem mass spectrometry (TOF-MS(n)) was used to identify both OSW-1, an acetylated cholestane diglycoside showing antitumor activity, and the cardiotonic steroid, bufotoxin. Each molecular-related ion was identified, and subsequent collision-induced dissociation experiments in which a molecular-related ion was selected as a precursor ion produced the characteristic product ions that are essential for structural elucidation. OSW-1 and its analogue with a modified side chain, thienyl OSW-1, were synthesized, and bufotoxins, i.e., marinobufotoxin and its homologue, marinobufagin 3-pimeloylarginine ester, were isolated from toad venom. On MALDI-TOF-MS, sodium-adduct [M+Na](+) ions were observed in the steroid glycosides, although protonated [M+H](+) ions were relatively more abundant than sodium-adduct [M+Na](+) ions in the bufotoxins. On the basis of tandem MS results, we propose key fragmentation pathways. The sugar moiety or side chain from the precursor ion was eliminated in OSW-1. However, characteristic product ions originating from the cleavage of the side chain with an ester formation were observed in the bufotoxins. Post-source decay (PSD) on MALDI-TOF-MS is also described when evaluating alpha-cyano-4-hydroxycinnamic acid or 2,5-dihydroxybenzoic acid as a matrix to obtain useful ions required for the identification of compound.

Novel digitalis-like factor, marinobufotoxin, isolated from cultured Y-1 cells, and its hypertensive effect in rats.

Marinobufagenin and telecinobufagin have been identified as digitalis-like factors in mammals. In toads, marinobufagenin-related compounds, such as marinobufotoxin (MBT), have been isolated in some tissues but not in mammals, and its biological action has not been elucidated. Herein, we aimed to explore the possible production and/or secretion of MBT and the biological action in rats. First, the MBT in culture supernatant of the adrenocortical-originated cell line Y-1 was analyzed by high-performance liquid chromatography and sensitive ELISA for marinobufagenin-like immunoreactivity. Moreover, the structural information was obtained by mass spectrometry. To determine the biological action, MBT (9.6 and 0.96 microg/kg per day) was intraperitoneally infused via an osmotic minipump for 1 week. Blood pressure and renal excretion of marinobufagenin-like immunoreactivity were measured. Marinobufagenin-like immunoreactivity was found in Y-1 cell culture media, and the concentration increased until 24 hours. The structural analysis suggested that marinobufagenin-like immunoreactivities were marinobufagenin and MBT, and tandem mass spectrum analysis revealed them with the specific daughter ions. The highest sensitive ELISA-positive peak of marinobufagenin-like immunoreactivity in the media was MBT. Continuous administration of MBT in rats for 1 week significantly increased systolic blood pressure and renal excretion of marinobufagenin-like immunoreactivity compared with control rats (135+/-3.0 versus 126+/-2.0 mm Hg and 1.41+/-0.286 versus 0.34+/-0.064 ng/day, respectively). These data suggest that MBT, arginine-suberoyl ester of marinobufagenin, can be a novel digitalis-like factor with hypertensive action and is secreted from the adrenocortical cells.

Potential antitumor agents: a cytotoxic cardenolide from Coronilla varia L.

An alcoholic extract of the seeds of Coronilla varia L. showed inhibitory activity against KB cells in culture and was fractionated through a series of partitions, column chromatography, and preparative layer chromatography to yield hyrcanoside, daphnoretin, scopoletin, and umbelliferone. Hyrcanoside was also tested in the PS mouse leukemia assay and showed borderline activity.

Partition high-pressure liquid-chromatographic systems for the separation of digitalis glycosides of the cardenolide group.

Several multi-component liquid-systems have been investigated on silica gel SI-60 supports of particle size 10 mum. By using two solvent systems, it was possible to separate 14 digitalis glycosides, ranging from genins of relatively low polarity to the highly polar deacetyl-lanatosides. Solvents with good ultraviolet transparency at 220 nm (lambdamax. for the butenolide ring) were chosen in order to improve the sensitivity of detection. The technique should also permit the determination of by-products and degradation products of these drug substances. Detection limits are as low as 15 ng for a 5 mul injection, and separation times vary between 4 and 20 min. The reproducibility of the retention times and the baseline separations attainable make the systems suitable for quantitative work.

Behaviour of cardiac glycosides and cardenolides related to digitoxigenin on sephadex LH-20.

The behaviour of six cardenolides and eight cardiac glycosides related to digitoxigenin during column chromatography on Sephadex LH-20 gel has been investigated. Complete resolution was obtained for mixtures of digitoxigenin, gitoxigenin and digoxigenin, but not for those of the 3-epimeric cardenolides. It was possible to achieve a group separation of cardenolides and their glycosides of the digitoxigenin series from those of the digoxigenin or gitoxigenin series.

Cardenolides of Trachomitum sarmatiense Woodson.

From the roots of Trachomitum sarmatiense Woodson (Apocynaceae) 5 cardial glycosides were isolated. Among them 4 substances were identified: cymarin and k-strophanthin-beta, and two derivatives of cannogen: apocannosid and apobiosid. In the overground part of the plant, the cardenolides were not found.

Chromatography on lipophilic dextran gels for fractionation of low molecular weight compounds II: separation of cardiac glycosides from cardiac aglycones.

A simple method is presented for the separation of cardiac glycosides from cardiac aglycones using highly cross-linked lipophilic dextran gel chromatography with 95% ethanol as the solvent.