I2/CF3CO2Ag-mediated iodolactonization of various allenoic acids to access versatile 6- to 9-membered ring vinylic iodolactones.

Medium-sized lactones are important structural units, but their synthesis remains a great challenge. Herein, we report I2/CF3CO2Ag-mediated iodolactonization of allenoic acids to synthesize various 6- to 9-membered ring vinylic iodolactones in 16-89% yield. This protocol not only develops a new cyclization strategy of allenoic acids, but also provides highly functionalized medium-sized lactones containing alkene and halogen groups.

Design, synthesis and biological evaluation of novel 3H-imidazole [4,5-b] pyridine derivatives as selective mTOR inhibitors.

A series of 3H-imidazo [4,5-b] pyridines derivatives were designed and synthesized as selective mTOR inhibitors. The systematic optimization of the molecules resulted in the identification of two compounds 10d and 10n with nanomolar mTOR inhibitory activity and selectivity over PI3Kα. Besides, compounds 10d and 10n demonstrated attractive potency against human breast cancer cells (MCF-7) and human ovarian cancer cell (A2780).

Optimization of dilution refolding conditions for a camelid single domain antibody against human beta-2-microglobulin.

Single domain antibody (sdAb) is often expressed as inclusion bodies in Escherichia coli cytoplasm. Establishing an effective in vitro refolding method for sdAb obtained from inclusion bodies would be important for sdAb research. In this study, dilution refolding condition for a camelid sdAb specific against human beta-2-microglobulin was optimized for the sdAb purified from the inclusion bodies of E. coli BL21 (DE3). Single factor methods based on protein concentration, velocity of dilution, incubation time and refolding buffer composition were first investigated. Then the key refolding buffer compositions were selected for further optimization by means of the Box-Behnken design of response surface methodology (RSM). The activity of the refolded sdAb was determined by measuring its specific antigen-binding ability using indirect ELISA. The optimized refolding condition of sdAb consisted of a 10-fold dilution in 10 mM Tris-HCl (pH 8.0) containing 1.24 mM GSH, 1mM GSSG, 352 mM L-Arg, 0.65% PEG-2000, and a 16 h incubation at 4 °C. Further comparison of the activities between the refolded sdAb and purified soluble sdAb expressed in E. coli Rosetta-gami (DE3) pLysS indicated that the sdAb was correctly refolded, as assayed by isothermal titration calorimetry. This work could provide an important strategy for the recombinant production and application of sdAb.

Synthesis of 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes via Er(OTf)3-catalyzed cascade reactions of p-quinone methides with 1,3-dicarbonyl compounds.

The Er(OTf)3-catalyzed cascade cyclization reaction of para-quinone methides (p-QMs) with various 1,3-dicarbonyl compounds has been developed, which efficiently constructed a series of versatile 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes. Herein, we not only propose a novel cyclization strategy of p-QMs, but also provide an easy access to structurally diverse coumarins and chromenes.

[Quantitative determination of the beta-2-microglobulin monomer by gel filtration chromatography].

Beta-2-microglobulin (B2M) is an important material in dialysis-related amyloidosis research. Unfortunately, the quantitative detection of the B2M monomer is difficult during B2M production. In this study, we established a method for the detection of the B2M monomer and its dimer in solution via gel filtration chromatography. The B2M powder was dissolved in 0.01 mol/L phosphate-buffered solution (PBS, pH 7.2-7.4) with a final mass concentration of 0.5 g/L. The B2M sample was analyzed on a TSKgel SuperSW2000 column (30 cm×4.6 mm, 4 µm) by an Agilent 1200 Series HPLC using 0.01 mol/L PBS (pH 7.2-7.4) as the mobile phase at a flow rate of 0.5 mL/min. The temperature of the column was 25℃, and the detection wavelength was 280 nm. The purities of the B2M monomer and the B2M dimer were tested. A series of concentrations of B2M monomer solutions were prepared to create a standard working curve. The standard working curve of the B2M monomer had a good linear relationship (coefficient of correlation (r2) was 0.9948). The limit of quantitation for the B2M monomer in PBS was 0.08 g/L (S/N=10). The recoveries were 85.0%-96.7% with relative standard deviations of 1.7%-3.3% at spiked levels of 0.10-0.30 g/L. The quantification of the B2M monomer was undisturbed by the B2M dimer, which can form during the B2M purification process. This determination method is simple, stable, and reliable for the determination of the B2M monomer in B2M industrial production.