Thiol-Functionalized Mesoporous Silica for Effective Trap of Mercury in Rats

The chance of exposure to heavy metal for human being rises severely today due to the increasing water contamination and air pollution. Here, we prepared a series of thiol-functionalized mesoporous silica as oral formulation for the prevention and treatment of heavy metal poisoning. The successful incorporation of thiol was verified by the FTIR spectra. SBA15-SH-10 was used for the study as it is of uniform mesopores and fine water dispersibility. In simulated gastrointestinal fluid, the thiol-functionalized mesoporous silica can selectively capture heavy metal, showing a very high affinity for inorganic mercury (II). The blood and urine mercury levels of rats fed with a diet containing Hg (II) and material were significantly lower than those of rats fed with the metal-rich diet only. On the contrary, the mercury content in fecal excretion of the treatment group increased more than twice as much as that of the control group. This result indicated that SBA15-SH-10 could effectively remove mercury (II) in vivo and the mercury loaded on SBA15-SH-10 would be excreted out. Hence, SBA15-SH-10 has potential application in preventing and treating heavy metal poisoning via digestive system

Synthesis of hexagonal mesoporous silicates functionalized with amino groups in the pore channels by a co-condensation approach

Mesoporous silicates functionalized with amino groups in the pore channels have been made by the co-condensation of tetraethoxyl siloxide (TEOS) with precursors of P-Si through a triblock copolymer-templated sol-gel process under acidic conditions. Poly(alkylene oxide) block copolymer (P123) was eluted by ethanol extraction and template molecules were removed by refluxing the materials in a mixture of DMSO and water. The resulting materials were characterized in detail by FT-IR, XRD, TEM and N-2 adsorption, in order to study the effect of the precursors on the mesoscopic order and pore structure. Evidence of amino groups located in the pore channels was shown through variation of pore size and BET surface area after the amino groups were coupled with benzaldehyde, and TEM images of materials after staining with RuO4. Finally, a comparative study of the catalytic performance of materials SBA-Am-10 and SBA-T-10, obtained by two methods, revealed that the catalyst synthesized by our method gave rapid reaction speed and high yields of flavanone by the Claisen-Schmidt condensation of benzaldehyde and 2'-hydroxyacetophenone

Reductive Hydrazination with Trichlorosilane: A Method for the Preparation of 1,1-Disubstituted Hydrazines

A straightforward and facile method has been developed to prepare 1,1-disubstituted hydrazines via Lewis base promoted direct reductive hydrazination. Under the catalysis of hexamethylphosphoramide (HMPA) and N,N-dimethylacetamide (DMAc), respectively, various ketones and aldehydes could react with phenylhdrazines to prepare 1,1-disubstituted hydrazines with good to high yields

Chiral Lewis Base-Catalyzed, Enantioselective Reduction of Unprotected beta-Enamino Esters with Trichlorosilane

Catalytic asymmetric reduction of N-unsubstituted beta-enamino esters represents a major challenge for asymmetric catalysis. In this paper, the first organocatalytic system that could be used for the asymmetric hydrosilylation of N-unsubstituted beta-enamino esters has been developed. Using N-tert-butylsulfinyl-L-proline-derived amides and L-pipecolinic acid-derived formamides as catalyst, a broad range of beta-aryl- and beta-alkyl-substituted free beta-amino esters could be prepared with high yields and enantioselectivities. The practicality was illustrated by the gram-scale asymmetric synthesis of ethyl (R)-3-amino-3-phenylpropanoate and isopropyl (S)-3-amino-4-(2,3,5-trifluorophenyl)butanoate. The resulting product can be smoothly transformed to the FDA approved medicines dapoxetine and sitagliptin in a short synthetic route

Synthesis of salicylaldehydes from phenols via copper-mediated duff reaction

A copper-mediated Duff reaction for ortho-selective formylation of phenols has been developed. In the presence of copper species, significant improvements of yield and ortho-selectivity of the Duff formylation were achieved, which provides an easy access to salicylaldehydes from phenols

Development of a New Marker System for Identification of Spirodela polyrhiza and Landoltia punctata

Lemnaceae (commonly called duckweed) is an aquatic plant ideal for quantitative analysis in plant sciences. Several species of this family represent the smallest and fastest growing flowering plants. Different ecotypes of the same species vary in their biochemical and physiological properties. Thus, selecting of desirable ecotypes of a species is very important. Here, we developed a simple and rapid molecular identification system for Spirodela polyrhiza and Landoltia punctata based on the sequence polymorphism. First, several pairs of primers were designed and three markers were selected as good for identification. After PCR amplification, DNA fragments (the combination of three PCR products) in different duckweeds were detected using capillary electrophoresis. The high-resolution capillary electrophoresis displayed high identity to the sequencing results. The combination of the PCR products containing several DNA fragments highly improved the identification frequency. These results indicate that this method is not only good for interspecies identification but also ideal for intraspecies distinguishing. Meanwhile, 11 haplotypes were found in both the S. polyrhiza and L. punctata ecotypes. The results suggest that this marker systemis useful for large-scale identification of duckweed and for the screening of desirable ecotypes to improve the diverse usage in duckweed utilization

Enzymatic cascades for the stereo-complementary epimerisation of in situ generated epoxy alcohols

The synthesis of optically pure secondary epoxy alcohols from racemic allylic alcohols using a single whole-cell biocatalyst of recombinant Escherichia coli coexpressing three oxidoreductases is described. The cascade involves the concurrent action of a styrene monooxygenase that catalyzes the formation of the chiral epoxy group, and two alcohol dehydrogenases that fulfil the epimerisation of the hydroxy group. Two sets of alcohol dehydrogenases were each applied to couple with styrene monooxygenase in order to realize the epimerisation in a stereo-complementary manner. Excellent enantio-and diastereoselectivities were achieved for most of the 12 substrates

2-Phenylbenzo[b]furans: Synthesis and promoting activity on estrogen biosynthesis

Estrogen biosynthesis is pivotal to many physiological processes of human. Aberrant estrogen level is closely related to a variety of diseases, including breast cancer and osteoporosis. Previously we found that 2phenylbenzo[b]furan glycosides could promote estrogen biosynthesis. To find high active 2-phenylbenzo [b]furans, fifty-four 2-phenylbenzo[b]furans were prepared via four strategies according to corresponding substrate scopes. Biological evaluation in HEK293A cells showed that some compounds exhibited promotive activity on estrogen biosynthesis. 2-(4-Chloropheny1)-7-methoxybenzo[b]furan possessed the highest activity with EC50 value of 14.68 mu M. Furthermore, these compounds did not affect aromatase expression in HEK292A cells, indicating that these 2-phenylbenzo[b]furans might enhance estrogen biosynthesis via directly allosteric regulation of aromatase or indirectly via posttranslational modification. (C) 2016 Elsevier Ltd. All rights reserved

Crystal structure and iterative saturation mutagenesis of ChKRED20 for expanded catalytic scope

ChKRED20 is an efficient and robust anti-Prelog ketoreductase that can catalyze the reduction of ketones to chiral alcohols as pharmaceutical intermediates with great industrial potential. To overcome its limitation on the bioreduction of ortho-substituted acetophenone derivatives, the X-ray crystal structure of the apo-enzyme of ChKRED20 was determined at a resolution of 1.85 and applied to the molecular modeling and reshaping of the catalytic cavity via three rounds of iterative saturation mutagenesis together with alanine scanning and recombination. The mutant Mut3B was achieved with expanded catalytic scope that covered all the nine substrates tested as compared with two substrates for the wild type. It exhibited 13-20-fold elevated k (cat)/K (m) values relative to the wild type or to the first gain-of-activity mutant, while retaining excellent stereoselectivity toward seven of the substrates (98-> 99% ee). Another mutant 29G10 displayed complementary selectivity for eight of the ortho-substituted acetophenone derivatives, with six of them delivering excellent stereoselectivity (90-99% ee). Its k (cat)/K (m) value toward 1-(2-fluorophenyl)ethanone was 5.6-fold of the wild type. The application of Mut3B in elevated substrate concentrations of 50-100 g/l was demonstrated in 50-ml reactions, achieving 75-> 99% conversion and > 99% ee

Bacterial community succession and metabolite changes during doubanjiang-meju fermentation, a Chinese traditional fermented broad bean (Vicia faba L.) paste

Doubanjiang-meju, a major ingredient of Chinese fermented food for several centuries, is produced using broad bean, wheat flour and salt. In this study, we investigated prokaryotic community succession and metabolite changes using high-throughput sequencing and H-1-NMR methods. After 35 days, bacterial communities, except Lactobacillus and Acinetobacter, were relatively stable until the end of fermentation, and consisted predominantly of the genera Tetragenococcus, Lactobacillus, Staphylococcus, Acinetobacter, Pseudomonas and Streptococcus. Glucose, arabinose, fructose and mannitol were identified as major sugars, lactate and acetate as major organic acids, and amino acids as the major nitrogen compounds present in doubanjiang-meju. Correlation analysis revealed important links between bacterial populations and metabolites, e.g., Pseudomonas was significantly correlated with 10 nitrogenous metabolites, while Streptococcus was significantly correlated with six carbonic metabolite and eight nitrogenous metabolites. These results not only revealed bacterial succession and dynamic changes in metabolites as well as pH and color, but also elucidated their relationships during the doubanjiang-meju fermentation. (C) 2016 Published by Elsevier Ltd