Pressurized hot water extraction of berberine, baicalein and glycyrrhizin in medicinal plants

Pressurized hot water extraction (PHWE) using a laboratory made system was applied for the extraction of thermally labile and reasonably polar components such as berberine in coptidis rhizoma, glycyrrhizin in radix glycyrrhizae/liquorice and baicalein in scutellariae radix. PHWE was carried out dynamically at a flow of 1 ml/min, temperature between 95 and 140 °C, an applied pressure of 10-20 bar and extraction time of 40 min. Extraction by PHWE was found to give efficiencies comparable to Soxhlet extraction for baicalein in scutellariae radix and sonication for berberine in coptidis rhizoma, and glycyrrhizin in radix glycyrrhizae. Effects of ethanol added into the water used in PHWE were explored. Pressurized liquid extraction (PLE) with methanol as solvent was used for extraction of baicalein in scutellariae radix. The marker compounds present in the various medicinal plant extracts were determined by gradient elution HPLC.     

Screening for inducers of kinase degradation

Targeted small molecule-induced protein degradation is a promising approach to inhibit signaling within kinase cascades. In this issue, researchers describe a simple assay for the rapid, high-throughput identification of novel agents that promote degradation of the kinases Her2 and EGFR.     

Proteomic analysis of mouse liver for the evaluation of effects of Scutellariae radix by liquid chromatography with tandem mass spectrometry

Scutellariae radix or Scutellaria baicalensis is a medicinal plant that contains major flavonoids such as baicalein, baicalin, wogonin and wogonosides. The present work describes the development of an approach using proteomic analysis of mouse liver to study the effects of prolonged exposure to substances present in chemically standardized Scutellariae radix extracts. Histopathological examination of the mouse liver was compared with the proteome data. The botanical extracts were prepared using pressurized liquid extraction (PLE). A method without isotope labeling was developed, using proteolytic digestion with one- and two-dimensional liquid chromatography with tandem mass spectrometry, and was used to characterize the extent of differential protein expression in mouse liver in response to external factors such as extracts from Scutellariae radix. From the histopathological examination and proteome data, significant changes in the mouse livers were not observed for the low-dose group. The Scutellariae radix extracts at high dose were observed to cause damage at the bile duct and expression change of a number of proteins including some involved in catabolism of triglyceride-rich particles, carbohydrate metabolism, regulators of cell signaling processes, and enzymes involved in biotransformation. Thus, proteomic analysis of liver samples from mice treated with botanical extracts is a promising approach to provide information on any potential toxicity effects of the extracts. The present method also provides another means for comparing proteomes in biological samples such as liver lysates from mice subjected to different treatments.     

Lignocellulosic biomass for bioethanol: Recent advances,technology trends,and barriers to industrial development

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Quantum chemical calculations and mutational analysis suggest heat shock protein 90 catalyzes trans-cis isomerization of geldanamycin

The affinity of geldanamycin (GA) for binding to heat shock protein 90 (HSP90) is 50- to 100-fold weaker than is the affinity of the structurally distinct natural product radicicol. X-ray crystallography shows that although radicicol maintains its free conformation when bound to HSP90, the conformation of GA is dramatically altered from an extended conformation with a trans amide bond to a kinked shape in which the amide group in the ansa ring has the cis configuration. We have performed ab initio quantum chemical calculations to demonstrate that the trans-cis isomeriztion of GA in solution is both kinetically and thermodynamically unfavorable. Thus, we propose that HSP90 catalyzes the isomerization of GA. We identify Ser113, a conserved residue outside the ATP binding pocket, as essential for the isomerization of GA. In support of this model, we show that radicicol binds equally well to both wild-type HSP90 and the Ser113 mutant, whereas the binding of GA to the Ser113 mutant is decreased significantly from its binding to wild-type HSP90. Based on this finding, a mechanism of keto-enol tautomerization of GA catalyzed by HSP90 is proposed. The added requirement of isomerization prior to tight binding may explain the enhanced binding affinity of GA for HSP90 in a cell extract versus in a purified form.     

Synthesis and 13C NMR of (trifluoromethyl)hydroxypyrazoles

Reaction of ethyl 4,4,4-trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5-hydroxy-3-(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3-hydroxy-5-(trifluoromethyl)pyrazole 4 . The structure assignments are established based on ¹³C nmr spectra. Compound 1 was converted to 5-chloro-3-(trifluoromethyl)pyrazolecarboxylic acid 3 in two steps.     

The preparation and properties of “porous silicon–nickel ferrite” nanoheterocomposites for gas detectors

This paper discusses the preparation and properties of gas detectors based on “porous silicon–nickel ferrite” nanocomposites. Impedance spectroscopy was used to measure sensitivity to ethanol and isopropanol vapours in the presence of an alternating electric field. The results were interpreted with the help of an equivalent electrical circuit. In the analysis of the resistive–capacitive properties in the equivalent circuit a constant phase element was used.     

Synthesis of 4-amino-5-H-2,3-dihydroisothiazole-1,1-dioxide ring systems on sugar templates via carbanion-mediated sulfonamide intramolecular cyclization reactions (CSIC protocols) of glyco-alpha-sulfonamidonitriles

The carbanion-mediated sulfonate intramolecular cyclizations (CSIC protocols) of glyco-alpha-sulfonamidonitriles derived from readily available monosaccharides have been extensively investigated using potassium carbonate, cesium carbonate, n-BuLi, and LDA as bases. As a result, a series of enantiomerically pure spiro(4-amino-5-H-2,3-dihydroisothiazole-1,1-dioxide) derivatives have been prepared efficiently and isolated in good yield. The synthesis of these new bicyclic systems is key to accessing a novel range of aza analogues of TSAO nucleosides (ATSAOs).     

Transport properties of carbon nanotube–metal nanocomposites

The performed investigations permit to reveal the effect of giant magnetic resistance in the specimens of the compacted nanocarbon materials containing multi-walled carbon nanotubes modified with the transition metals (Fe and Co).     

Optical properties of porous silicon processed in tetraethyl orthosilicate

We investigate the change in the composition and optical properties of porous silicon (por-Si) obtained by electrochemical etching of a palate made of n-type (111) silicon single crystal under high-temperature annealing and processing in tetraethyl orthosilicate (TEOS). It is shown that TEOS processing and annealing prevent contamination of a sample stored for a long time in atmosphere. The processing of por-Si in TEOS does not change the position of the photoluminescence (PL) peak and suppresses PL to a smaller extent as compared to annealing of por-Si. This increases the reliability of optoelectronic devices based on por-Si.