Yali Zhang

Evaluation to the antioxidant activity of total flavonoids extract from persimmon (Diospyros kaki L.) leaves

Persimmon leaves are commonly consumed as beverages, but are also used as a popular folk medicine in China. The purpose of this work is to assess the antioxidant activity of an extract of total flavonoids from persimmon leaves (TFPL). The effect of TFPL on total antioxidant activity, reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH()) radical scavenging, superoxide anion (()O(2)(-)) radical scavenging, hydroxyl (OH()) radical scavenging and metal chelating activities was examined. We found that TFPL possesses considerable amounts of flavonoids (192μg catechin equivalent/g of extract). The effect of this extract in total antioxidant activity, scavenging activity of superoxide anion and hydroxyl radical, reducing power and iron chelating activity was significantly better than that of rutin. However, the effect of TFPL in free radical scavenging of DPPH() was significantly not as good as than rutin. In addition, TFPL significantly decreased the level of reactive oxygen species (ROS) and malondialdehyde (MDA), while increasing the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in MC3T3-E1 cells in a dose-dependent manner. In conclusion, TFPL possess potent antioxidant and free radical scavenging activities. These antioxidant activities could contribute, at least in part, to the traditionally claimed therapeutic benefits of persimmon leaves.

Sustained release of PI3K inhibitor from PHA nanoparticles and in vitro growth inhibition of cancer cell lines

The phosphoinositide-3-kinases (PI3Ks) are a conserved family of lipid kinases that phosphorylate the 3-hydroxyl group of phosphatidylinositols in response to extracellular stimuli. PI3K pathway is enrolled in different kinds of human cancer and plays a prominent role in cancer cell growth and survival. Several PI3K inhibitors have been recently identified but some PI3K inhibitors with high potency in vitro do not show satisfactory effects in animal cancer models because of the poor pharmaceutical properties in vivo such as poor solubility, instability, and fast plasma clearance rate. In this study, we developed a sustained release system of PI3K inhibitor (TGX221) based on polyhydroxyalkanoate nanoparticles (NP) and used it to block proliferation of cancer cell lines. TGX221 was gradually released from PHA-based NP and growth of cancer cell lines was significantly slower in NP-TGX221-treated cells than in either negative controls or in cells receiving free TGX221. Since poor bioavailability and limited in vivo half-life are common features of hydrophobic PI3K inhibitors, our results open the way to similar formulation of other PI3K blockers and to new strategies in cancer treatment.

Sulphated modification of a polysaccharide obtained from fresh persimmon (Diospyros kaki L.) fruit and antioxidant activities of the sulphated derivatives

Free radicals and other reactive oxygen species (ROS) are believed to play significant roles in ageing as well as in a number of degenerative or pathological diseases. This paper reports the preparation, characterisation and potential antioxidant activity of a type of chemically sulphated polysaccharide isolated from fresh persimmon (Diospyros kaki L.) fruit. Three sulphated derivatives with variable degrees of substitution (0.8, 1.7 and 2.5) were obtained by the chlorosulphonic acid-pyridine method. The sulphated derivatives all showed dose-dependent reducing power and free radical scavenging effect of 1,1-dipheny-l-2-picrylhydrazyl, superoxide anion and hydroxyl. Our results showed that the sulphated modification of polysaccharides significantly increased their antioxidant activities and may be an effective way to prepare these valuable derivatives.

Sulfated modification and immunomodulatory activity of water-soluble polysaccharides derived from fresh Chinese persimmon fruit

In this study, three kinds of chemically sulfated polysaccharides (PFP-S) were derived from a water-soluble polysaccharide of persimmon fruit with chlorosulfonic acid-pyridine method. Relationship between the degree of substitution and immunomodulatory activity of PFP-S was examined with the splenocytes experiment. The results showed that the splenocytes-activating activity was significantly enhanced by PFP-S in all the groups compared with control group (P<0.01). PFP-SII exhibited the most potent splenocytes-activating activity by increased cytokine production and NO release. It also suggested that the sulfate groups and molecular weight of polysaccharides are key factors to regulate the immunomodulatory activities.

Engine Wear Monitoring with OLVF

In this article, an on-line visual ferrograph (OLVF) was used to monitor the wear condition of a vehicle engine during a bench test. A quantitative index of particle coverage area (IPCA) and wear debris ferro-image were obtained via OLVF to characterize wear degrees. On-line ferrograph analysis indicated some problems with the engine from about the 17th hour. A linear threshold value method to identify running condition of engines with the OLVF data was proposed. The OLVF data were in a fault zone after running for 25 h, when a base bolt broke and the engine stopped working during the test. The engine was disassembled and inspected after the test. Several wear scars were found on the cylinder walls as well as on the bearing surfaces. The oil was added at the 26th and 55th hours, which was also reflected by the variation of IPCA. Moreover, several off-line analyses were carried out in parallel. Off-line ferrograph data did not give any information about the abnormality and only showed stable wear debris content. Spectrometric oil analysis showed that there was no significant change in contents of metal elements.

Response of MC3T3-E1 osteoblast cells to the microenvironment produced on Co–Cr–Mo alloy using laser surface texturing

Osteoblast responses to Co–Cr–Mo alloy depend on not only the chemistry of alloy but also the physical properties of alloy surface, such as its microtopography and roughness. This study was undertaken to examine changes in cell adhesion, morphology, differentiation and gene expression during osteoblast interaction with different textured Co–Cr–Mo alloys. With laser surface texturing, three kinds of textured surfaces were fabricated. It showed that the microenvironment processed by laser surface texturing leads to an increase in surface roughness and DMEM contact angles of samples. Adhesion and differentiation tests demonstrated that osteoblast cells can discriminate surfaces with different roughness and surfaces with comparable roughness but different topographies such as triangle, circle and square textures. Morphological characteristics obtained by SEM imaging showed that osteoblast cells are elongated and are in polygonal shape on the textured surface. OPG/RANKL mRNA expression studies showed a significant and marked decrease in RANKL gene expression on the square-textured surface; by contrast, the ratio of OPG/RANKL showed a significant increase. These results indicate that Co–Cr–Mo surface textures affect osteoblast proliferation, morphology and gene expression; the microenvironment of implant should be considered in the future design.

Description of Wear Debris from On-Line Ferrograph Images by Their Statistical Color

Analytical ferrography has been proved to be one of the most popular methods for wear characterization. However, it is limited by the real-time requirement of condition-based monitoring. A new wear characterization by on-line ferrograph images is proposed. The color of wear debris was studied based on an on-line visual ferrograph (OLVF) sensor. Generally, the features of on-line ferrograph images included low resolution, high contamination, and wear debris chains. The weak color of the wear debris, especially nonferrous metal debris, in an on-line ferrograph image was unavoidably merged into the mass noises. Accordingly, the on-line images were converted from the initial red, green, blue (RGB) format into hue, saturation, intensity (HSI) for the description of color images. The transmitted image was binarized to locate all wear debris and the wear debris was extracted by their pixels from the corresponding reflected image. The distributions of two HSI components, hue and intensity, were used to characterize the color of on-line ferrograph images. Aiming at the global noise induced by uneven light during sampling, the distributions of the hue and intensity of the wear debris were subtracted by that of the reflected image. As a result, the statistical colors of wear debris were extracted with the hue and intensity from the on-line ferrograph images. A designed experiment with manually prepared oil samples revealed that the wear debris of three common metals could be well differentiated according to their colors via the on-line ferrograph images. The method provides a primary exploration on describing the color of wear debris by on-line ferrograph images.

Sulfation modification and anticoagulant activity of the polysaccharides obtained from persimmon (Diospyros kaki L.) fruits

The optimal conditions for sulfation of polysaccharides from persimmon fruits (PFP) with chlorosulfonic acid-pyridine (CSA-Pyr) method were determined by response surface methodology. Box-Behnken design was applied to evaluate the effects of three independent variables (volume ratio of Pyr to CSA, volume ratio of PFP to SO(3)Pyr and reaction time) on the degree of substitution (DS), molecular weight (MW) and activated partial thromboplastin time (APTT) of sulfated polysaccharides (PFP-S). The APTT activity of PFP-S could be improved by application of various volume ratio of Pyr to CSA, volume ratio of PFP to SO(3)Pyr and reaction time, which was possible due to the degradation of polysaccharides to different extent and increasing of DS. The optimal conditions to obtain the strongest APTT of PFP-S were the volume ratio of CSA to Pyr of 1:8, the volume ratio of SO(3)Pyr to PFP of 1:3.6 and the reaction time of 3 h, respectively.

Protective effects of sulfated chitooligosaccharides against hydrogen peroxide-induced damage in MIN6 cells.

Sulfated chitooligosaccharides (COS-S) with different degrees of substitution (DS) were obtained by the chlorosulfuric acid/pyridine method. Protective effects of COS-S against hydrogen peroxide (H(2)O(2))-induced damage were investigated in pancreatic β-cells MIN6 cell line. The cell viability, morphology, insulin contents, malondialdehyde (MDA) inhibition, lactate dehydrogenase (LDH) release and the levels of antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidise (GPx) were evaluated under oxidative damage by 150 μM H(2)O(2) for 6h. COS-S did not show any harmful or inhibitory effect on cell growth at concentrations ranging from 0.1 to 0.5 mg/ml. While COS-S could enhance the cell viability, decrease the production of ROS, and reduce the MDA level as well as LDH level in oxidative damaged β-cells by being an antioxidant. The underlining mechanisms of protective effects of COS-S are partly due to the enhancement of antioxidant enzyme activity and inhibition of intracellular ROS production, along with suppressing MIN6 cell apoptosis subsequent to the amelioration of ROS. Moreover, increased DS might contribute to the defense mechanisms against H(2)O(2)-induced oxidative damage in MIN6 cells. These results indicated that the antioxidant properties of COS-S hold great potential for the oxidative diseases treatment, and the sulfate content of polysaccharides made great role in regulating antioxidant activities.

Protective effects of sulfated chitooligosaccharides with different degrees of substitution in MIN6 cells.

Chitosan, a naturally occurring biopolymer, has received considerable attention for pharmaceutical applications due to its biocompatible, biodegradable and less toxic properties. In this study, sulfated chitooligosaccharides (COS-S) with different degrees of substitution (DS) were prepared to improve both its water-solubility and bioactivity. Additionally, the protective effects of COS-S on hydrogen peroxide (H(2)O(2))-induced dysfunction in MIN6 cells were investigated. COS-SI (DS, 0.8) and COS-SII (DS, 1.9) significantly increased the cell viability in a dose-dependent manner. COS-S also significantly suppressed NO production, the activity and mRNA expression of iNOS, and the protein level of NF-κB protein p65, which were activated by H(2)O(2). Furthermore, we demonstrated that COS-S led to an increase in the Bcl-2/Bax mRNA expression ratio and the inhibition of Caspase-3 mRNA expression in H(2)O(2)-stimulated MIN6 cells. Additionally, COS-SII (DS, 1.9) exhibited a superior protective effect on H(2)O(2)-induced apoptosis compared to COS-SI (DS, 0.8). These results indicated the good anti-oxidative capacity of COS-S and the possible mechanism via the blockade of the NF-κB signaling pathway. The protective effects of COS-S against oxidative injuries in MIN6 cells were depended on both DS and concentration.