Wenjian Yang

Concentrations and health risks of lead, cadmium, arsenic, and mercury in rice and edible mushrooms in China

In this study, four common heavy metals, lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in rice and edible mushrooms of China were studied to evaluate contamination level and edible safety. Ninety two (92) rice samples were collected from the main rice growing regions in China, and 38 fresh and 21 dry edible mushroom samples were collected from typical markets in Nanjing City. The analyzed metal concentrations were significantly different between rice and edible mushroom samples (p<0.05). The results showed that Pb, Cd and As contents in 4.3%, 3.3% and 2.2% rice samples respectively, were above maximum allowable concentration (MAC). In fresh edible mushroom, Pb and Hg contents in 2.6% samples were above MAC, respectively. However, only Hg content in 4.8% dry edible mushroom samples was above its MAC. Therefore, more than 95% rice and edible mushroom samples in our test had high edible safety.

Purification, characterization and antitumor activity of polysaccharides from Pleurotus eryngii residue.

A novel water-soluble polysaccharide from Pleurotus eryngii residue was isolated and further purified by DEAE cellulose-52 chromatography and Sephadex G-100 size-exclusion chromatography to yield PEPE-1, PEPE-2 and PEPE-3. Molecular weights were determined by high-performance size-exclusion chromatography (HPSEC). Gas chromatography (GC) analysis of monosaccharide composition confirmed that PEPE-1, PEPE-2 and PEPE-3 were heteropolysaccharides and mainly composed of glucose. Sulfate and uronic acid content, ultraviolet and infrared spectrum were also evaluated. The antitumor activities of the polysaccharides against HepG-2 cells were studied in vitro. Results showed that the three polysaccharides could suppress the proliferation and enhance lactate dehydrogenase (LDH) release of HepG-2 cells in a dose- and time-dependent manner. The effect increased in the order of PEPE-1<PEPE-2<PEPE-3, respectively. The same order was also observed with uronic acid content. Findings presented in this study suggested that the polysaccharides extracted from P. eryngii residue might be suitable for functional foods and natural antitumor drugs development.

Effect of hot air drying on volatile compounds of Flammulina velutipes detected by HS-SPME-GC-MS and electronic nose.

Volatile compounds are important factors that affect the flavor quality of Flammulina velutipes, but the changes occurring during hot air drying is still unclear. To clarify the dynamic changes of flavor components during hot air drying, comprehensive flavor characterization and volatile compounds of F. velutipes were evaluated using electronic nose technology and headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Results showed that volatile components in F. velutipes significantly changed during hot air drying according to the principal component analysis and radar fingerprint chart of electronic nose. Volatile compounds of fresh F. velutipes consisted mainly of ketones, aldehydes and alcohols, and 3-octanone was the dominant compound. Drying process could significantly decrease the relative content of ketones and promoted the generation of alcohols, acids, and esters, which became the main volatile compounds of dried F. velutipes. These may provide a theoretical basis for the formation mechanism of flavor substances in dried F. velutipes.

Simultaneous determination of arsenic and mercury species in rice by ion-pairing reversed phase chromatography with inductively coupled plasma mass spectrometry.

An analytical method using reversed phase chromatography-inductively coupled plasma mass spectrometry for arsenic and mercury speciation analysis was described. The effect of ion-pairing reagent on simultaneous separation of four arsenic (arsenite, arsenate, monomethlyarsonate and dimethylarsinate) and three mercury species (inorganic mercury (Hg(II)), methylmecury and ethylmercury) was investigated. Parameters including concentrations and pH of the mobile phase were optimized. The separation and re-equilibration time was attained within 20min. Meanwhile, a sequential extraction method for arsenic and mercury in rice was tested. Subsequently, 1% HNO3 microwave-assisted extraction was chosen. Calibration curves based on peak area measurements were linear with correlation coefficient greater than 0.9958 for each species in the range studied. The detection limits of the species were in the range of 0.84-2.41μg/L for arsenic and 0.01-0.04μg/L for mercury, respectively. The proposed method was then successfully applied for the simultaneous determination of arsenic and mercury species in rice flour standard material and two kinds of rice from local markets.

Effect of stable antimicrobial nano-silver packaging on inhibiting mildew and in storage of rice

Antimicrobial nano-silver packaging (ANP) films were synthesized by blending polyethylene and highly dispersed Ag/TiO2 powder for rice storage at 37°C and 70% relative humidity. ANP films were characterized by X-ray diffraction and silver migration. The antimicrobial activity of the films was assessed on Aspergillus flavus (A. flavus) by scanning electron microscope and total plate count, and the storage quality of rice was evaluated by texture analyzer and rapid viscosity analyzer. The results show that ANP had a quite beneficial effect on the antimildew and physicochemical property as compared to the normal PE packaging. During 35days storage, the migration of silver into rice was not evident. A lower microbial population is observed on ANP that should be attributed to the presence of Ag/TiO2. Furthermore, rice packed by ANP shows an enhanced quality with regards to texture and pasting properties. Therefore, ANP is a promising packaging material for rice storage.

Cytotoxicity and apoptotic effects of tea polyphenol-loaded chitosan nanoparticles on human hepatoma HepG2 cells

Tea polyphenols have strong antioxidant and antitumor activities. However, these health benefits are limited due to their poor in vivo stability and low bioavailability. Chitosan nanoparticles as delivery systems may provide an alternative approach for enhancing bioavailability of poorly absorbed drugs. In this study, tea polyphenol-loaded chitosan nanoparticles have been prepared using two different chitosan biomaterials, and their antitumor effects were evaluated in HepG2 cells, including cell cytotoxicity comparison, cell morphology analysis, cell apoptosis and cell cycle detection. The results indicated that the tea polyphenol-loaded chitosan nanoparticles showed a branch shape and heterogeneous distribution in prepared suspension. MTT assay suggested that tea polyphenol-loaded chitosan nanoparticles could inhibit the proliferation of HepG2 cells, and the cytotoxicity rates were increased gradually and appeared an obvious dose-dependent relationship. Transmission electron microscope images showed that the HepG2 cells treated with tea polyphenol-loaded chitosan nanoparticles exhibited some typical apoptotic features, such as microvilli disappearance, margination of nuclear chromatin, intracytoplasmic vacuoles and the mitochondrial swelling. In addition, the tea polyphenol-loaded chitosan nanoparticles had relatively weak inhibitory effects on HepG2 cancer cells compared with tea polyphenols. Tea polyphenols not only induced cancer cell apoptosis, but also promoted their necrosis. However, tea polyphenol-loaded chitosan nanoparticles exhibited their antitumor effects mainly through inducing cell apoptosis. Our results revealed that the inhibition effects of tea polyphenol-loaded chitosan nanoparticles on tumor cells probably depended on their controlled drug release and effective cell delivery. The chitosan nanoparticles themselves as the delivery carrier showed limited antitumor effects compared with their encapsulated drugs.

Antiproliferative and immunostimulatory activity of a protein from Pleurotus eryngii.

BACKGROUND Currently, the use of mushrooms as functional foods, nutraceuticals or phytopharmaceuticals source has risen. In contrast, the possible cellular cytotoxicity and immunostimulatory activity of Pleurotus eryngii (DC. ex Fr.) Quel protein (PEQP) is unknown. Here we report extraction, anti-tumorigenic and immunostimulatory activity of PEQP in vitro. RESULTS PEQP was extracted from the dried fruiting bodies of P. eryngii, purified and characterised. Its in vitro antiproliferative activity was then evaluated in human non-small cell lung cancer A549 (NSCLC), stomach adenocarcinoma BGC-823, hepatocellular carcinoma HepG2 and gastric carcinoma HGC-27 cell lines using conventional cancer drugs (paclitaxel, doxorubicin and mitomycin C) as positive controls. The protein fractions (PEQP 1, 2, 3 and 4) obtained inhibited tumour cell proliferation dose-dependently with fraction PEQP 2 having significant (P < 0.05) toxicity in all tumour cells. PEQP had no significant toxicity on normal liver Chang cells but their proliferation was significantly inhibited by mitomycin C. Moreover, PEQP stimulated the proliferation, lysosomal enzyme activity, pinocytosis, nitric oxide and hydrogen peroxide production of RAW 264.7 cell lines dose-dependently. CONCLUSION Based on these results, P. eryngii protein has a potential application in functional foods as a natural anti-tumour agent with immunostimulatory activity.

Development, physiochemical characterization and forming mechanism of Flammulina velutipes polysaccharide-based edible films

Edible films of Flammulina velutipes polysaccharide were prepared and characterized in terms of rheological, optical, morphologic, mechanical and barrier properties to evaluate their potential application in food packaging. Results suggested that FVP film prepared by the solution of 1:150 (w/v) had the optimal mechanical property, smooth and uniform surface, and good barrier property to water (37.92±2.00gmm/m(2)hkPa) and oxygen (37.92±2.01meq/kg). The capacity of film-formation might be related to inter-molecular and intra-molecular hydrogen bonds of FVP and formation of β-glycosidic bonds during the process of film-formation. These findings will contribute to a theoretical basis for the development of FVP film in food packaging.

Immunopotentiation of Pleurotus eryngii (DC. ex Fr.) Quel

ETHNOPHARMACOLOGICAL RELEVANCE Pleurotus eryngii (DC. ex Fr.) Quel has been collected from the wild, cultivated and used in traditional medicines to treat various disorders and diseases since antiquity. In traditional Chinese medicine, the powdered fruiting bodies of Pleurotus eryngii were used for immunostimulation, skin-care, wound-healing, cancer and lumbago treatment. In the current study, we investigated the antiproliferative activity of Pleurotus eryngii powder on A549, BGC-823, HepG2 and HGC-27 cancer cells and its immunomodulating activity on macrophage, RAW 264.7 cells based on its active compound. MATERIALS AND METHODS A novel bioactive protein (PEP) was extracted from Pleurotus eryngii fruiting bodies powder and purified on DEAE-52, CM-52 and Superdex 75 column chromatographies using an ÄKTA purifier. Its cytotoxicity on A549, BGC-823, HepG2, HGC-27 and RAW 267.4 cell lines was then evaluated using MTT, alamar blue (AB), trypan blue (TB), neutral red (NR), lactate dehydrogenase (LDH), Annexin V FITC/PI and morphological change assays. Moreover, lysosomal enzyme activity, pinocytosis, nitric oxide (NO) and hydrogen peroxide (H₂O₂) production assays were used to examine immunomostimulatory activity of PEP on RAW 267.4 cells. RESULTS Based on high performance gel permeation chromatography (HPGPC), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) analyses, the isolated protein (PEP) had a molecular weight of 63 kDa, a secondary (α-helical) structure and was mainly composed of arginine, serine and glycine. PEP significantly (P<0.05) inhibited A549, BGC-823, HepG2 and HGC-27 tumor cells proliferation dose-dependently with an IC₅₀ range of 36.5 ± 0.84 to 229.0 ± 1.24 µg/ml. Contrarily, PEP stimulated the proliferation of macrophages. CONCLUSION Pleurotus eryngii fruiting bodies powder has a potential application as a natural antitumor agent with immunomodulatory activity, proposedly, by targeting the lysosomes of cancerous cells and stimulating macrophage-mediated immune responses.

Immunoregulatory role of Pleurotus eryngii superfine powder through intercellular communication of cytokines

Pleurotus eryngii, also known as thistle mushroom, is rich in proteins, dietary fibre and polysaccharides. It has been developed as a functional food due to its antioxidant, anti-fatigue, anti-viral and anti-tumour functions. The objective of this study was to investigate the mechanisms of the immunoregulatory and antioxidant effects of P. eryngii superfine powder (PESP) in vivo. Test mice were fed with a diet containing 6.67% PESP to explore its effect on mouse delayed-type hypersensitivity, phagocytic index, serum hemolysin, serum and liver glutathione peroxidase (GSH-PX) activities, serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in liver homogenate. For the human study, volunteers received PESP at doses of 5, 10 or 15 g. Serum levels of 39 cytokines were determined before and after ingestion using a Millipore Human Kit and a liquid chip scanner. Our results showed that, in mice, dietary P. eryngii supplementation significantly increased the weight difference of ears (P < 0.01), phagocytic index (P < 0.05), serum hemolysin (P < 0.01), serum and liver GSH-PX activities (P < 0.01) and serum SOD activity (P < 0.01), but decreased MDA content (P < 0.01) in liver homogenate. In human trials, 5 g of PESP significantly decreased serum epidermal growth factor, while 15 g of PESP significantly decreased serum granulocyte–macrophage colony stimulating factor, macrophage-derived chemokine and tumour necrosis factor-α. No change was detected in serum cytokines after the administration of 10 g of PESP. P. eryngii can regulate innate and acquired immune functions in mice to execute antioxidant and anti-aging functions, and can alter human serum cytokines. The dual immunoregulatory effects of P. eryngii are consistent with the theory of traditional Chinese medicine.