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In the present study, a total of 11 compounds were isolated from the aerial parts of Glycyrrhiza uralensis, including two new compounds, glycyuralin Q (1) and glycyuralin R (2), and nine known compounds, including licoriphenone (3), orobol (4), trifoliol (5), 7,2′,4′-trihydroxy-5-methoxy-3-arylcoumarin (6), 11-hydroxy-9(Z),12(Z)-octadecadienoic acid (7), 11-hydroxy-9(E), 12(E)-octadecadienoic acid (8), licoricone (9), glycyrin (10), and 2′-hydroxyformononetin (11). Structures of the new compounds were identified by 1D, 2D NMR and HR-MS data analyses. Compounds 1, 2 and 10 showed potent inhibitory activities against PTP1B, with IC50 values of 1.43, 4.71 and 3.79 μM, respectively. Compounds 2, 4 and 10 inhibited α-glucosidase with IC50 values of 13.61, 11.13 and 17.48 μM, respectively. [ABSTRACT FROM AUTHOR]

The spontaneous formation of organic helical structures, accompanied with an amplification of chirality, by dynamic covalent bonds between achiral and chiral building blocks is reported. [ABSTRACT FROM AUTHOR]

Proteins are naturally evolved macromolecules with highly sophisticated structures and diverse properties. The design and controlled self-assembly of proteins into polymeric architectures via supramolecular interactions offers unique advantages in understanding the spontaneously self-organisational process and fabrication of various bioactive materials. This feature article highlights recent advances and future trends in supramolecular polymers that are directly assembled from the building blocks of proteins. Non-covalent interactions capable of inducing polymerization include aromatic π-π stacking, host-guest interactions, metal coordination, and interprotein interactions combined with site-selective protein modification to explore the dynamic and specific unidirectional aggregation behaviours among protein units. We also discuss some extended supramolecular protein polymers achieved by rational design and fine-tuning the protein-protein interactions, which may help to inspire future design of more complicated polymeric protein assemblies. The protein-based supramolecular polymer system provides a versatile platform for functionalization and thereby shows great potential in the development of novel biomaterials with controlled structures and properties. [ABSTRACT FROM AUTHOR]

Mimicking the properties of the selenoenzyme glutathione peroxidase (GPx) has inspired great interest. In this report, a selenium-containing micellar catalyst was successfully constructed by the self-assembly of the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) with benzeneseleninic acid (PhSeO2H) through hydrophobic and electrostatic interaction in water. The selenium-containing micellar catalyst demonstrated substrate specificity for both 3-carboxy-4-nitrobenzenethiol (ArSH, 2) and cumene hydroperoxide (CUOOH), and their complexation was confirmed by UV and fluorescence spectra. More importantly, it demonstrated high GPx activity in two assay systems. It is about 126 times more effective than the well-known GPx mimic ebselen in the classical coupled reductase assay system; however, by using hydrophobic substrate ArSH (2) as an alternative of glutathione (GSH, 1), the micellar catalyst exhibited remarkable 500-fold and 94 500-fold rate enhancements compared with that of PhSeO2H and PhSeSePh. [ABSTRACT FROM AUTHOR]

It has long been known that tellurium compounds are rather toxic to living organisms, and tellurium has not been found in natural biomacromolecules to date. The principles of telluride toxicity in biological processes are still controversial partly because of the lack of information on the biochemical features of tellurium. In this contribution, we report our finding for the first time that telluroxides exhibit hydrolysis capacity. For instance, 6,6′-telluroxy-bis(6-deoxy-β-cyclodextrin) acts as a hydrolase mimic and shows a significant rate acceleration of 106 000 for the hydrolysis of 4,4′-dinitrodiphenyl carbonate. [ABSTRACT FROM AUTHOR]

Artificial glutathione peroxidase (GPx) model 2, 2'-ditellurobis(2-deoxy-β-cyclodextrin) (2-TeCD) which has the desirable properties exhibited high substrate specificity and remarkably catalytic efficiency when 3-carboxy-4-nitrobenzenethiol (ArSH) was used as a preferential thiol substrate. The complexation of ArSH with β-cyclodextrin was investigated through UV spectral titrations, fluorescence spectroscopy, 1H NMR and molecular simulation, and these results indicated that ArSH fits well to the size of the cavity of β-cyclodextrin. Furthermore, 2-TeCD was found to catalyze the reduction of cumene peroxide (CuOOH) by ArSH 200 000-fold more efficiently than diphenyl diselenide (PhSeSePh). Its steady-state kinetics was studied and the second rate constant kmax/KArSH was found to be 1.05 × 107 M-1 min-1 and similar to that of natural GPx. Moreover, the kinetic data revealed that the catalytic efficiency of 2-TeCD depended strongly upon the competitive recognition of both substrates for 2-TeCD. The catalytic mechanism of 2-TeCD catalysis agreed well with a ping-pong mechanism, in analogy with natural GPx, and might exert its thiol peroxidase activity via tellurol, tellurenic acid, and tellurosulfide. [ABSTRACT FROM AUTHOR]

The article reports on the preparation of the first semisynthetic telluroenzyme, tellurosubtilisin, which was generated by chemically introducing tellurium into the binding site of subtilisin and then acted as an excellent glutathione peroxidase (GPx) mimic. Along with the successful chemical modification of subtilisin to thiol/selenosubtilisin, the semisynthetic GPx mimic, tellurosubtilisin, was prepared via a three-step protocol. The resulting telluroprotein was aerially oxidized and then purified by gel filtration on Sephadex G-25 and affinity chromatography on thiopropyl-Sepharose 6B.

The synthesis of quinoline-derived helically folded aromatic oligoamides functionalized by various chiral functions at their N-terminus is reported. When a (1S)-(-)-camphanyl moiety was introduced, it was found that helix handedness was completely shifted to right-handed helicity (de > 99%), in both protic and nonprotic solvents. The absolute helical sense and the de values were unambiguously characterized by using 1H NMR, circular dichroism (CD), and X-ray crystallography. The crystal structure of these compounds allowed us to propose a rationale for the efficiency of helix handedness induction based on a combination of steric factors and intramolecular hydrogen bonding. [ABSTRACT FROM AUTHOR]

A type of aromatic helical capsules was synthesized. The crystal structure proved an inner cavity that could perform switchable encapsulation and release of potassium ion through protonation/deprotonation-mediated extension and contraction of molecular motion. [ABSTRACT FROM AUTHOR]

Researchers report the synthesis of the three generations of Fréchet-type poly(aryl ether) dendrimers with a diselenide core that demonstrate generation-dependent glutathione peroxidase (GPx) activity with initial reduction rates for the third-generation product. GPx is a mammalian antioxidant seleno-enzyme that protects biomembranes and other cellular components from oxidative damage by catalyzing the reduction of a variety of hydroperoxides, using glutathione as the reducing substrate. The catalytic active center of GPx, selenocysteine, is in a depression on the protein surface, in which some charged and hydrophobic amino acid residues from a hydrophobic cavity. The discovery of Ebselen which functions as an antioxidant, has inspired a worldwide interest in the design of GPx mimics.

The cooperative self-assembly of polystyrene-b-poly(4-vinylpyridine) block copolymers (BCPs) and gold nanoparticles (AuNPs) confined within the emulsion droplets is studied by combining both the experiments and Monte Carlo simulations. The results indicate that the entropic interaction between the AuNPs and BCP domain is a critical parameter to dominate the spatial arrangement of AuNPs and the nanostructure of the hybrid nanoparticles, which can be utilized to design novel hierarchical hybrid nanoparticles. Based on this theoretical observation, a large number of unique Janus hybrid nanoparticles, including pupa-like nanoparticles with AuNPs concentrated at one pole of the particles, spherical nanoparticles with AuNPs enriched in a bulge on the sphere surface, and the gourd-like, clover-like, and four-leaf-clover-like nanoparticles from the further hierarchical assembly of small hybrid Janus nanoparticles, are fabricated via three-dimensional (3D) confined self-assembly. [ABSTRACT FROM AUTHOR]