An effective β-cyclodextrin polyurethane spherical adsorbent for the chromatographic enrichment of corilagin from Phyllanthus niruri L. extract

Spectroscopic and mechanistic analysis of the interaction between Jack bean urease and polypseudorotaxane fabricated with bis-thiolated poly(ethylene glycol) and α-cyclodextrin

Self-assembled polypseudorotaxanes (PPRXs) fabricated with α-cyclodextrin and poly(ethylene glycol) (PEG) or its thiolated derivatives were candidate functional materials for enzyme soft-immobilization, encapsulation and controlled-release. The study of their interaction with Jack bean urease (JBU) indicated that they inconspicuously influenced the activity and stability of JBU during long storage, up to 30 days. The macro-species were inaccessible to JBU's active site and the steric effect might play a significant role in the stabilization of JBU, when compared with the small-molecular sulfhydryl inhibitor thioglycolic acid. Circular dichroism and fluorescence spectra analyses revealed that thiolated PEG₄₀₀-(SH)₂ and its assembly PPRX₄₀₀(SH) brought in perturbations to certain α-helical or β-sheet domains of JBU, making JBU's conformation more flexible. The resulting partial unfolding of domains exposed several hydrophobic clusters and varied JBU's surface hydrophobicity. It also rendered the chromophores more hydrophilic and more bared to the polar environment, leading to the typical bathochromic-shift and quenching in intrinsic and synchronous fluorescence spectra. Moreover, the surface hydrophobicity profile of JBU was depicted by fluorescent probe monitoring and the unique "hydrophobic cave" motif was proposed by analyzing JBU's structural data from the Protein Data Bank. It should be pointed out that conformational variations mainly occurred at the surface region of JBU, while the buried active bi-nickel center was not markedly influenced by the macro-species. The results demonstrated that the PPRXs might act as a proper carrier for JBU encapsulation or soft-immobilization.

Chemical Components and Biological Activities of the Genus Phyllanthus: A Review of the Recent Literature

Medicinal plants have served humans since prehistoric times to treat various ailments. Both developed and underdeveloped countries rely on traditional systems of medication using natural sources from plants. Phyllanthus is one of the largest genus in the family Phyllanthaceae, comprising over 700 well known species cosmopolitan in distribution mainly in the tropics and subtropics. Phyllanthus species are being in constant used in traditional medications to cure an array of human diseases (constipation, inhalation related, arthritis, loss of appetite, injuries, conjunctivitis, diarrhoea, running nose, common cold, malaria, blennorrhagia, colic, diabetes mellitus, dysentery, indigestion, fever, gout, gonorrheal diseases of males and females, skin itching, jaundice, hepatic disorders, leucorrhea, vaginitis, menstrual irregularities, obesity, stomach pains, and tumors), confectionaries, food industry, and in some pesticides. Phyllanthus species are rich in diversity of phytochemicals e.g., tannins, terpenes, alkaloids, glycosidic compounds, saponins, and flavones etc. More in depth studies are a direly needed to identify more compounds with specific cellular functions to treat various ailments.

α-chymotrypsin activated and stabilized by self-assembled polypseudorotaxane fabricated with bis-thiolated poly(ethylene glycol) and α-cyclodextrin: Spectroscopic and mechanistic analysis

The self-assembled polypseudorotaxane (PPRX) fabricated with bis-thiolated poly(ethylene glycol) (PEG) and α-cyclodextrin (α-CyD) acted as an activator for α-chymotrypsin (CT) and retained the activity of CT for a long time up to 7days. The stabilization mechanism was studied, and the interaction between CT and PPRX was analyzed by using circular dichroism, fluorescence spectra and X-ray powder diffraction (XRD). The bis-thiolated PEG and its assembled PPRX with α-CyD exhibited the interaction with the C-terminal region of the CT's B-chain probably through PEGylation of the surface disulfide bridge of CT. It caused the aromatic chromophores more exposed to the hydrophilic microenvironment, leading to conformational variation of CT that was revealed by spectroscopic analysis. It rendered the peptide chains in a more flexible and active state. As a comparison, the non-thiolated components could not decorate the surface of CT and performed almost no effect on its stability, which demonstrated that the decoration of the surface disulfide bridge was a key factor in retaining the activity of CT. Due to the activation and stabilization effect, bis-thiolated PEG/α-CyD PPRX was an excellent soft-immobilized carrier for CT, and provided an intriguing method for enzyme's stabilization.

Theoretical and experimental studies on the separation of cinnamyl acetate and cinnamaldehyde by adsorption onto a β-cyclodextrin polyurethane polymer

CAc and CA were separated using CDPU as adsorbent, and the mechanism was proposed through DFT calculations and experimental analyses.