Biosynthetic activity of recombinant Escherichia coli-expressed Pichia etchellsii β-glucosidase II

The hydrolysis and biosynthetic reactions of partially purified Pichia etchellsii β-glucosidase II from recombinant Escherichia coli pBG22:JM109 are described. With 167 mmol/L of initial glucose, the products of synthetic reactions, glucobiose and glucotriose, accumulated to 18 and 6 mmol/L, respectively. In transglycosylation reactions with 79 mmol/L of initial cellobiose, glucotriose and glucopentaose were obtained at 4.5 and 2 mmol/L, respectively. The effects of incubation time and substrate concentration were studied on the yield of synthesized oligosaccharides. In a reaction time of 24 h with 468 mmol/L of initial cellobiose, glucotriose and glucopentaose levels of 21.6 and 6.6 mmol/L, respectively, were obtained. The addition of dimethyl sulfoxide (DMSO) further increased the yields of the products by 10%. Detailed kinetic analysis indicated a significant (about twofold) increase in V _max/K _M of synthetic reactions in the presence of DMSO. A study of other disaccharides in transglycosylation reactions indicated biosynthetic activity in the order of sophorose > gentiobiose > cellobiose.     

A “One Pot,” Environmentally Friendly,Multicomponent Synthesis of 2‐Amino‐5‐cyano‐4‐[(2‐aryl)‐1H‐indol‐3‐yl]‐6‐hydroxypyrimidines and Their Antimicrobial Activity

A series of multifunctional 2‐amino‐5‐cyano‐4‐[(2‐aryl)‐1H‐indol‐3‐yl]‐6‐hydroxypyrimidines ( 4a , 4b , 4c , 4d , 4e , 4f ) was synthesized by multicomponent reaction of 3‐formylindole ( 1 ), cyanoethylacetate ( 2 ), and guanidine hydrochloride ( 3 ) with NaOH by using green chemical techniques, viz. microwave irradiation and grindstone technology. The same reactants when refluxed in ethanol also gave titled compounds ( 4a , 4b , 4c , 4d , 4e , 4f ). Compared with conventional procedure, the reaction can be carried out under milder conditions, requiring a shorter reaction time and giving higher yields following the green chemistry methodology. All the synthesized compounds have been characterized on the basis of elemental analyses and spectral data (IR, ¹H NMR, ¹³C NMR, and mass). All synthesized compounds were also evaluated for their antimicrobial activity against nine pathogenic bacteria, antifungal activity against Rhizopus stolonifer, Aspergillus flavus, and Fusarium oxysporum and antibacterial activity against Escherichia coli and Pseudomonas aeruginosa at different concentrations. Most of the compounds showed mild to moderate activity.     

Spin-assembled nanolayer of a hyperbranched polymer on the anode in organic light-emitting diodes: the mechanism of hole injection and electron blocking

We introduced a spin-assembled nanolayer of hyperbranched poly(ether sulfone) with sulfonic acid terminal on top of an indium-tin oxide anode in organic light-emitting diodes. This results in great improvement in luminous efficiency, better than that of devices using a commercially available conducting polymer composition as a hole-injection layer. The effect of the nanolayer was investigated by impedance spectroscopy, photovoltaic measurement for built-in-potential, and transient electroluminescence. We concluded that the high luminous efficiency resulted from the efficient electron-blocking by the nanolayer and hole-injection assisted by the accumulation of electrons at the interface. This result implies that, for an efficient hole-injection layer, the electron-blocking capability should be incorporated in addition to the hole-injection and -transport capability.     

Synthesis,spectral, and antimicrobial studies of 1‐butyl‐3‐substituted‐4‐(2‐aryl‐1H‐indol‐3‐yl)‐2‐azetidinones

Ketene generated from acetyl chloride or chloroacetyl chloride adds on indolyl Schiff's base double bond to afford 1‐butyl‐3‐substituted‐4‐(2‐aryl‐1H‐indol‐3‐yl)‐2‐azetidinones in THF. The reaction proceeds stereospecifically via concerted trans [2+2] cycloaddition. The synthesized compounds have been characterized by elemental analyses and spectral data (IR, PMR, and mass). All synthesized compounds have been evaluated for antibacterial and antifungal activities, and 4g to 4l have shown promising results. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:494–501, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20052     

Cytotoxicity of in vitro produced podophyllotoxin from Podophyllum hexandrum on human cancer cell line

Podophyllotoxin was produced by cell culture of Podophyllum hexandrum under in vitro culture conditions. A maximum of 4.26 mg/L of podophyllotoxin was produced when P. hexandrum was cultivated in 3 L stirred tank bioreactor. The compound extracted from the cell culture was applied to the human breast cancer cell line (MCF-7) and 1 nM podophyllotoxin was able to inhibit the growth of the cancer cells by 50%. The most profound inhibitory effect of podophyllotoxin was observed when it was applied in the beginning of cell growth.     

A ‘one pot’ synthesis of 2‐aryl‐4H‐1‐benzopyran‐4‐ones under coupled microwave phase transfer catalysis (PTC) and ultrasonic irradiation PTC

A ‘one pot’ synthesis of 2‐aryl‐4H‐1‐benzopyran‐4‐ones (3a‐3f) is being reported. A mixture of o‐hydroxyacetophenone, aroyl chloride, powdered n‐tetrabutylammonium hydrogensulphate (n‐TBAHSO₄) and potassium hydroxide (KOH) were either irradiated by microwaves or sonicated in an ultrasonic cleaning bath to afford flavones directly. On the contrary, conventional liquid‐liquid Phase Transfer Catalysis (PTC) using benzene as organic phase and aqueous KOH as the second phase afforded first β‐diketones in accordance with Baker‐Venkataraman synthesis which upon cyclization by p‐toluenesulphonic acid (p‐TSA) gave desired flavones in the next step. PTC coupled with microwaves or ultrasound show enhanced yields, the clean reaction conditions require less time, and have easier workup protocol. All synthesized compounds were characterized by their Proton Magnetic Resonance (PMR), IR, FAB Mass and elemental analyses.     

Dielectric properties of a highly polar liquid crystalline material showing various types of layered structures

Liquid crystal compound N-(4-n-pentyloxybenzalidene) 4′-n-pentylaniline is very interesting because of its rich phase variant, i.e. nematic, smectic A, smectic C, smectic F and smectic G phases. In the present work, temperature- and frequency-dependent dielectric studies on this compound in the homeotropic and planar orientation of molecules have been carried out in the frequency range of 1 Hz–10 MHz. The compound shows negative dielectric anisotropy (i.e. Δε < 0). Dielectric studies have shown three relaxation modes of different origin in various phases of the material. Relaxation frequencies of the observed modes follow Arrhenius behaviour. The relaxation due to interfacial polarisation, i.e. Maxwell–Wagner–Sillars effect has been observed in the nematic and isotropic phases. A relaxation mode due to the fluctuation of molecular tilt resembling the soft mode has been detected in the smectic A phase with pre- and post-transitional effects. Another mode due to the fluctuation of molecules about their short axes has been detected in the nematic and smectic A, C, F and G phases. Activation energies and ionic conductivity of these phases have also been determined.     

Eco-Friendly Synthesis and Insecticidal Activity of Some Fluorinated 2-(N-Arylamino)-4-Arylthiazoles

A series of fluorinated 2-(N-arylamino)-4-arylthiazoles (3) was synthesized by the condensation of appropriate arylthioureas (2) with corresponding α-bromoacetophenones (1) by using “green chemistry” techniques, viz. mechanochemical mixing and microwave or ultrasonic irradiation. Compared with conventional procedures, the reaction can be carried out under milder conditions, requiring a shorter reaction time and giving higher yields following the green chemistry methodology. All the synthesized compounds were characterized on the basis of elemental analyses and spectral data (IR, ¹H NMR, and mass spectrometry). Representative compounds were also evaluated for their insecticidal activity against Helicoverpa armigera, and some of them showed promising activity.

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