Man Xu

Microwave-assisted extraction of polyphenols from Camellia oleifera fruit hull.

The abundant fruit hulls of tea-oil tree (Camellia oleifera) are still underutilized and wastefully discaded to pollute the environment. In order to solve this problem and better utilize the fruit hulls of C. oleifera, a microwave-assisted extraction system was used to extract their polyphenols using water as the extraction solvent. A central composite design (CCD) was used to monitor the effects of three extraction processing parameters – liquid:solid ratio (mL/g), extraction time (min) and extraction temperature (°C) – on the polyphenol yield (%). The results showed that the optimal conditions were liquid:solid ratio of 15.33:1 (mL/g), extraction time of 35 min and extraction temperature of 76 °C. Validation tests indicated that under the optimized conditions the actual yield of polyphenols was 15.05 ± 0.04% with RSD = 0.21% (n = 5), which was in good agreement with the predicted yield. Phenolic compounds in the extracts were analysed by HPLC, and gallic acid was found to be the predominant constituent. The total flavonoid content in the extracts was determined and high total flavonoid content was revealed (140.06 mg/g dry material).

Phenolic Extracts from Acacia mangium Bark and Their Antioxidant Activities

Phenolic compounds are present at very high concentrations in the bark of Acacia mangium. These compounds are known to have strong antioxidant activity and thus different beneficial effects on human health. Phenolic compounds in bark of A. mangium were extracted and their antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging and ferric-reducing antioxidant power (FRAP) assays. A central composite design has been employed to optimize the experimental conditions for a high total phenolic content and antioxidant activity. The desirability function approach has been employed to simultaneously optimize the three responses: total phenols, antiradical activity and FRAP. An extraction time of 90 min, liquid-solid ratio of 5, and temperature of 50 °C was predicted for the optimum experimental conditions using the desirability function. A significant linear relationship between antioxidant potency, antiradical activity and the content of phenolic compounds of bark extracts was observed. The structures of condensed tannins isolated from A. mangium were characterized by MALDI-TOF MS analyses. Condensed tannin oligomers from A. mangium were shown to be heterogeneous mixtures consisting of procyanidin and prodelphinidin structural units with polymerization degrees up to 9.

Redox/pH dual stimuli-responsive degradable Salecan-g-SS-poly(IA-co-HEMA) hydrogel for release of doxorubicin.

Salecan is a novel water-soluble extracellular β-glucan and possesses excellent physicochemical and biological properties. Here, redox/pH dual stimuli-responsive hydrogel based on Salecan grafted with itaconic acid (IA) and 2-hydroxyethyl methacrylate (HEMA) were prepared using disulfide-functionalized crosslinker N,N-bis(acryloyl)cystamine (BAC) for controlled drug delivery. The introduction of carboxylic groups endows the system with pH-sensitive character, swelling behavior of the hydrogel was conducted by changing the pH and Salecan content. It was demonstrated that DOX was efficiently loaded into the hydrogels and released in a controlled fashion via pH-control and swelling-shrinking mechanism. More importantly, DOX-loaded hydrogels showed dose dependent cytotoxicity toward A549 cell, and efficient cell killing was observed. Furthermore, a key point of this study was that the presence of disulfide linkage in system favored the degradation of hydrogels in the reductive environment. These results highlight the potential of Salecan-g-SS-poly(IA-co-HEMA) hydrogel as a novel system for the controlled release of anti-cancer drugs.

Optimizing ultrasonic ellagic acid extraction conditions from infructescence of Platycarya strobilacea using response surface methodology.

The infructescence of Platycarya strobilacea is a rich source of ellagic acid (EA) which has shown antioxidant, anticancer and antimutagen properties. Response surface methodology (RSM) was used to optimize the conditions for ultrasonic extraction of EA from infructescence of P. strobilacea. A central composite design (CCD) was used for experimental design and analysis of the results to obtain the optimal processing parameters. The content of EA in the extracts was determined by HPLC with UV detection. Three independent variables such as ultrasonic extraction temperature (°C), liquid:solid ratio (mL/g), and ultrasonic extraction time (min) were investigated. The experimental data obtained were fitted to a quadratic equation using multiple regression analysis and also analyzed by appropriate statistical methods. The 3-D response surface and the contour plots derived from the mathematical models were applied to determine the optimal conditions. The optimum ultrasonic extraction conditions were as follows: ultrasonic extraction temperature 70 °C, liquid:solid ratio 22.5, and ultrasonic extraction time 40 min. Under these conditions, the experimental percentage value was 1.961%, which is in close agreement with the value predicted by the model.

Effect of metal ions on the binding reaction of (−)-epigallocatechin gallate to β-lactoglobulin

The effects of metal ions (Cu2+, Sn2+, Zn2+, Mn2+, Al3+ and Fe3+) on the interaction between (-)-epigallocatechin-3-gallate (EGCg) and β-lactoglobulin (β-Lg) were investigated via fluorescence and circular dichroism (CD) spectroscopy. The results of the fluorescence titration experiment demonstrated that the addition of Cu2+ increases the quenching efficiency of EGCg to β-Lg by more than EGCg alone, while Mn2+, Al3+ and Zn2+ decrease the quenching efficiency of EGCg to β-Lg by less than EGCg alone. [β-Lg-Mn], [β-Lg-Al], [β-Lg-Zn] and [β-Lg-Sn] obviously decreased the apparent binding affinities (Ka) of EGCg to β-Lg by 95.53%, 81.94%, 44.66% and 38.58%, respectively, whereas [β-Lg-Cu] significantly increased the Ka of EGCg for β-Lg by 115.44%. The results of CD spectroscopy experiment showed the α-helix content of β-Lg decreased with the addition of Cu or Al, indicating that the β-Lg-Cu and β-Lg-Al interaction resulted in unfolding of the secondary structure of β-Lg.

Fabrication of Salecan/poly(AMPS-co-HMAA) semi-IPN hydrogels for cell adhesion

Salecan is a novel water-soluble extracellular β-glucan and has excellent physicochemical and biological properties. A series of hydrogels were fabricated from Salecan and poly(2-acrylamido-2-methylpropanesulfonic acid-co-N-hydroxymethyl acrylamide) (poly(AMPS-co-HMAA), PAH) by semi-IPN technique. The introduction of Salecan into the PAH network endows the system with enhanced cell adhesion properties. These semi-IPN hydrogels with open interconnected pores had pH and salt-sensitive swelling behavior. The increase in the content of hydrophilic Salecan could enhance the water uptake of the hydrogels. Rheological results indicated that the incorporation of PAH into hydrogels increased the storage modulus. The degradation property of the hydrogels can be tuned by modulating the content of Salecan and BAAm. Cytotoxicity results revealed that the hydrogels were non-toxic to COS-7 cells. All these results suggested that Salecan/PAH semi-IPN hydrogels exhibited great potential for applications in soft tissue engineering.

Magnetic field-driven drug release from modified iron oxide-integrated polysaccharide hydrogel

Salecan is a novel water-soluble extracellular β-glucan and suitable for the hydrogel preparation due to its excellent physicochemical and biological properties. The present article describes the fabrication and characterization of a pH/magnetic field-driven hydrogel based on salecan-g-poly(vinylacetic acid-co-2-hydroxyethyl acrylate) [poly(VA-co-HEA)] copolymer and Fe3O4@Agarose nanoparticles for drug release testing. Vibrating sample magnetometer characterization verified that integration of Fe3O4@Agarose nanoparticles in the copolymer provided the sensitivity to magnetic fields. The doxorubicin hydrochloride (DOX) release test showed a pH/magnetic field-triggered and sustained release property, and the release could be accelerated under mildly acidic conditions or the presence of an external magnetic field. Meanwhile, the increase in salecan content could also enhance the release rate. Cytotoxicity assays revealed that the released DOX maintained relatively high killing efficacy of A549 cells. In sum, these salecan-g-poly(VA-co-HEA)/Fe3O4@Agarose hydrogels were well-suited for magnetically targeted drug delivery systems.

Dual-pH/magnetic field-controlled drug delivery systems based on Fe3O4@SiO2-incorporated Salecan graft copolymer composite hydrogel

Salecan is a water‐soluble extracellular β‐glucan and has excellent physicochemical and biological properties for hydrogel preparation. In this study, a new pH/magnetic field dual‐responsive hydrogel was prepared by the graft copolymerization of salecan with 4‐pentenoic acid (PA) and N‐hydroxyethylacrylamide (HEAA) in the presence of Fe3O4@SiO2 nanoparticles for doxorubicin hydrochloride (DOX) release. Integration of Fe3O4@SiO2 nanoparticles in salecan‐g‐poly(PA‐co‐HEAA) copolymers afforded magnetic sensitivity to the original material. DOX‐loaded hydrogels exhibited a clear capacity for pH/magnetic field dual‐responsive controlled drug release. Lowering the pH to acidic conditions or introducing an external magnetic field caused an enhancement in DOX release. This salecan‐g‐poly(PA‐co‐HEAA)/Fe3O4@SiO2 composite hydrogel is a promising drug carrier for magnetically targeted drug delivery with enhanced DOX cytotoxicity against A549 cells.

Acid hydrolysis of crude tannins from infructescence of Platycarya strobilacea Sieb. et Zucc to produce ellagic acid

The infructescence of Platycarya strobilacea Sieb. et Zucc is a well-known traditional medicine in China, Japan and Korea. The infructescence of P. strobilacea Sieb. et Zucc is a rich source of ellagitannins that are composed of ellagic acid (EA) and gallic acid, linked to a sugar moiety. The aim of this study was to prepare EA by acid hydrolysis of crude tannins from the infructescence of P. strobilacea Sieb. et Zucc, and establish a new technological processing method for EA. The natural antioxidant EA was prepared by using the water extraction of infructescence of P. strobilacea Sieb. et Zucc, evaporation, condensation, acid hydrolysis and prepared by the process of crystallisation. The yield percentage of EA from crude EA was more than 20% and the purity of the product was more than 98%, as identified by using HPLC. The structure was identified on the basis of spectroscopic analysis and comparison with authentic compound.

Design of a pH-sensitive magnetic composite hydrogel based on salecan graft copolymer and Fe 3 O 4 @SiO 2 nanoparticles as drug carrier

Salecan, a novel water-soluble extracellular β-glucan, is very suitable for the hydrogel preparation. Here, pH-sensitive magnetic composite hydrogel was fabricated by the graft copolymerization of crotonic acid (CA) and N-(hydroxymethyl) acrylamide (HMAA) onto salecan in the presence of Fe3O4@SiO2 nanoparticles for doxorubicin (DOX) delivery. The embedment of Fe3O4@SiO2 nanoparticles into salecan-g-poly(CA-co-HMAA) hydrogel network endowed the material with magnetic property. In addition, DOX not only achieved effectively bound to the composite hydrogel, but also released in a controlled and pH-dependent manner. The application of an external magnetic field could significantly enhance the drug release rate. More importantly, the released DOX preserved its bioavailability. Taken together, these hydrogel drug carriers provide a promising platform for magnetically targeted drug delivery.