Five Novel Taccalonolides from the Roots of the Vietnamese Plant Tacca paxiana

Chemical investigation of the roots of the Vietnamese plant Tacca paxiana resulted in the isolation of five new steroidal compounds, taccalonolide R ( 6 ), S ( 7 ), T ( 8 ), U ( 9 ), and V ( 10 ). Their structures were established on the basis of NMR and mass‐spectral data. In addition, the five known taccalonolides A ( 1 ), B ( 2 ), E ( 3 ), K ( 4 ), and N ( 5 ) were also isolated and identified.     

From Enantiopure Hydroxyaldehydes to Complex Heterocyclic Scaffolds: Development of Domino Petasis/Diels–Alder and Cross‐Metathesis/Michael Addition Reactions

One‐step assembly of hexahydroisoindole scaffolds by a sequence that combines the Petasis (borono‐Mannich) and Diels–Alder reactions is described. The unique selectivity observed experimentally was confirmed by quantum calculations. The current method is applicable to a broad range of substrates, including free sugars, and holds significant potential to efficiently and stereoselectively build new heterocyclic structures. This easy and fast entry to functionalized polycyclic compounds can be pursued by further transformations, for example, additional ring closure by a cross‐metathesis/Michael addition domino sequence.     

Development and validation of an ELISA kit for the detection of ricin toxins from biological specimens and environmental samples

Ricin is a toxin that can be easily extracted from seeds of Ricinus communis plants. Ricin is considered to be a major bio-threat as it can be freely and easily acquired in large quantities. A deliberate release of such toxin in civilian populations would very likely overwhelm existing public health systems, resulting in public fear and social unrest. There is currently no commercially available or FDA-approved prophylaxis such as vaccines, or therapeutic antitoxins or antidotes, available for ricin intoxication. Patient treatment is typically supportive care based on symptoms, often designed to reinforce the body’s natural response. This paper describes the development and validation of a robust ELISA test kit, which can be used to screen for ricin in biological specimens such as whole blood and faeces. Faecal specimens are shown in this study to have better diagnostic sensitivity and a wider diagnostic window compared to whole blood. From these results, it is concluded that faeces is the most suitable clinical specimen for diagnosis of ricin poisoning via the oral route. The ELISA test kit can also detect ricin in environmental samples. An advantage of this ELISA kit over other commercial off-the-shelf (COTS) detection kits currently on the market that are developed to screen environmental samples only is its ability to diagnose ricin poisoning from clinical specimens as well as detect ricin from environmental samples.     

Estimation of radon and thoron caused dose at exraction and processing sites of mineral sand mining area in Vietnam (HA TINH province)

Mineral sands are mined in several countries to supply to the titanium and zircon producing industries. Coastal black mineral sands usually contain, besides ilmenite (FeTiO₃) and rutile (TiO₂), radioactive minerals such as zircon (ZrSiO₄) and monazite (RePO₄). Radon and thoron activity concentration originated from natural radioactive contents of the black mineral sand was monitored at the extraction and processing for black minerals in the coastal areas of Ha Tinh Province, one of the around 40 coastal mineral sand deposits in Vietnam. The survey was carried out with the Raduet chambers made by Radosys Ltd—Hungary. The obtained results for 25 investigated points show that the measured values are not high in the residential houses and in case of the sand extraction site as well. At the titanium processing plant the measured values were higher than outside the facility (Radon: 18–55 Bq/m³ with average of 34 Bq/³ and Thoron 33–118 Bq/m³ with average of 58 Bq/m³) but still comparable to the average concentration of the world published by UNSCEAR. The typical outdoor levels of radon and thoron gas are each of the order of 10 Bq/m³. Although the radon concentrations were low in the zircon and titanium processing plants, the thoron concentrations in the houses for separating rutile and zircon were very high. At zircon processing factory, the thoron concentration could reach 2,931 Bq/m³ and the estimated annual effective dose would be 21.4 mSv/a. Intervention has to be taken in order to reduce the thoron level in this factory since the level of thoron and its progenies corresponding to an annual occupational effective dose is beyond the action level of 6 mSv/a.     

Investigation of Growth Conditions for the Expansion of Porcine Mesenchymal Stem Cells on Microcarriers in Stirred Cultures

The extensive use of mesenchymal stem cells (MCS) in tissue engineering and cell therapy increases the necessity to improve their expansion. Among these, porcine MCS are valuable models for tissue engineering and are classically expanded in static T-flasks. In this work, different processes of stirred cultures were evaluated and compared. First, the effect of glucose, glutamine, antioxidant, and growth factors concentrations on porcine MSC expansion were analyzed in a suitable medium by performing kinetic studies. Results showed that a lower glucose concentration (5.5 mM) enabled to increase maximal cell concentration by 40 % compared with a higher one (25 mM), while addition of 2 to 6 mM of glutamine increased maximal cell concentration by more than 25 % compared with no glutamine supplementation. Moreover, supplementation with 1 μM thioctic acid increased maximal cell concentration by 40 % compared with no supplementation. Using this adapted medium, microcarriers cultures were performed and compared with T-flasks expansion. Porcine MSC were shown to be able to proliferate on the five types of microcarriers tested. Moreover, cultures on Cytodex 1, Cytopore 2, and Cultispher G exhibited a MSC growth rate more than 40 % higher compared with expansion in T-flasks, while MSC metabolism was similar.     

Regioselective cycloaddition of C-carbamoylnitrones to methyl (E)-2-(2-phenylcyclopropylidene)acetate and methyl (E)-2-methylidene-3-phenylcyclopropane-1-carboxylate

N-Aryl-C-(arylcarbamoyl)nitrones regioselectively add to methyl 2-(2-phenylcyclopropylidene)-acetate and methyl 2-methylidene-3-phenylcyclopropanecarboxylate to give in each case two diastereoisomeric 5-oxa-6-azaspiro[2.4]heptane-4-carboxylates.     

Synthesis and molecular structure of substituted 2-hydroxyperhydro-[1,3,2]dioxaborinino[5,4-<Emphasis Type="Italic">c</Emphasis>]pyridines,perhydro[1,3]dioxano[5,4-<Emphasis Type="Italic">c</Emphasis>]pyridine,and their precursor-4-hydroxy-3-(α-hydroxybenzyl)-1-methyl-4-phenylpiperidine

4,8a-Diphenyl-substituted 2-(2-propoxy)perhydro[1,3,2]dioxaborinino[5.4-c]pyridine was obtained by the condensation of 4-hydroxy-3-(α-hydroxybenzyl)-1-methyl-4-phenylpiperidine with triisopropyl borate, and its 2-hydroxysubstituted analog in the presence of water. 1-Methyl-4,8a-diphenyl-perhidro[1,3]dioxano[5,4-c]pyridine was synthesized by the reaction of the same piperidol with formaldehyde. A comparative study of the molecular structures of the three products was carried out by X-ray crystallography. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1726–1735, November, 2008.     

Chiral ionic liquids for enantioseparation of pharmaceutical products by capillary electrophoresis

A chiral ionic liquid (IL), S-[3-(chloro-2-hydroxypropyl)trimethylammonium] [bis((trifluoromethyl)sulfonyl)amide] (S-[CHTA](+)[Tf(2)N](-)), which can be easily and readily synthesized in a one-step process from commercially available reagents, can be successfully used both as co-electrolyte and as a chiral selector for CE. A variety of pharmaceutical products including atenolol, propranolol, warfarin, indoprofen, ketoprofen, ibuprofen and flurbiprofen, can be successfully and baseline separated with the use of this IL as electrolyte. Interestingly, while S-[CHTA](+)[Tf(2)N](-) can also serve as a chiral selector, enantioseparation cannot be successfully achieved with S-[CHTA](+)[Tf(2)N](-) as the only chiral selector. In the case of ibuprofen, a second chiral selector, namely a chiral anion (sodium cholate), is needed for the chiral separation. For furbiprofen, in addition to S-[CHTA](+)[Tf(2)N](-) and sodium cholate, a third and neutral chiral selector, 1-S-octyl-beta-d-thioglucopyranoside (OTG), is also needed. Due to the fact that the chirality of this chiral IL resides on the cation (i.e., -[CHTA](+)), and that needed additional chiral selector(s) are either chiral anion (i.e., cholate) or chiral neutral compound (OTG), the results obtained seem to suggest that additional chiral selector(s) are needed to provide the three-point interactions needed for chiral separations.