Peter C K Cheung

The Chinese University of Hong Kong, Hong Kong, Hong Kong

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Publications (79)142 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Pleurotus tuber-regium (Fries) Singer (PTR), both an edible and medicinal mushroom also known as tiger milk mushroom, has a growing popularity and economic importance due to its flavor, nutritive value and medicinal effects. In this study, the anti-oxidant and anti-angiogenic activities of a 60% ethanol extract (EE) obtained from the sclerotium of PTR was investigated. Typical phenolic compounds including protocatechuic, chlorogenic, syringic, ferulic, folic acid were identified and quantified in EE by the HPLC-UV-ESI/MS analyses. EE possessed strong antioxidant activity and could dose-dependently inhibit vascular endothelial growth factor (VEGF)-induced human umbilical vein endothelial cells (HUVEC) migration and tube formation. qPCR results showed that VEGF-induced FGF, ANG-TIE and MMP gene expression as well as VEGFR were down-regulated at the mRNA level after treated with EE, suggesting that multiple molecular targets related to angiogenesis was involved. Furthermore, EE also inhibited the formation of sub-intestinal vessel plexus (SIVs) in zebrafish embryos in vivo. All of these suggested that EE of PTR could be the source of potential inhibitors to target angiogenesis.
    Journal of agricultural and food chemistry. 09/2014;
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    Lei Chen, Bo-Bo Zhang, Jia-Lun Chen, Peter C.K. Cheung
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    ABSTRACT: The fine molecular structure of a novel alkali-soluble polysaccharide (SCA-I) from the mushroom sclerotial cell wall of Pleurotus tuber-regium was elucidated by 1-D and 2-D NMR spectroscopy as a hyper-branched glucan having a 64.9% degree of branching at O-6 and consisting a main chain with →1)-Glcp-(4→ linkages and short side chains having either →1)-Glcp-(3→ or →1)-Glcp-(6→ linkages. This partial structure of SCA-I was consistent with that obtained from methylation analysis. The molecular conformation of SDS-treated SCA-I was visualized for the first time by TEM and AFM. Microscopic images confirmed the highly branched structure of SCA-I as well as its multiple chain conformation when its compact structure was opened up by SDS treatment. This unique hyper-branched polysaccharide has the potential application in the design of carbohydrate-based nano-particles and drug delivery systems.
    Food Hydrocolloids 07/2014; 38:48-55. · 3.49 Impact Factor
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    Lei Chen, Wenwen Xu, Shaoling Lin, Peter C.K. Cheung
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    ABSTRACT: The cell wall structure of mushroom sclerotium was investigated by a fractionation of its soluble cell wall polysaccharides followed by chemical, physico-chemical and microscopic analyses. The present results suggest that cell wall structure of Pleurotus tuber regium sclerotium contains three main layers: an outer layer of glycoproteins, a middle layer of hyper-branched glucans and an inner layer of complex between hyper-branched glucan and chitin. The structure of the hyper-branched glucans were elucidated by the methylation analysis to be composed of →1)-Glcp-(4→ linkages as the backbone with some →1)-Glcp-(6→ linkages existed in the side chains, while some →1)-Glcp-(3→ linkages might exist in the backbone or side chains. SEC-MALLS analysis revealed that hyper-branched β-glucans had a Mw ranging from 1.4 to 5.2 × 106 g/mol and R.M.S. radius ranging from 26 nm to 38.5 nm. SEM and AFM further showed that hyper-branched β-glucans were spherical in shape when dispersed in water.
    Food Hydrocolloids 05/2014; 36:189-195. · 3.49 Impact Factor
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    Lei Chen, Peter C K Cheung
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    ABSTRACT: Cell wall of mushroom fruiting body is constituted of non-digestible macromolecules that are a rich source of dietary fiber with biological functions that are beneficial to human health. The cell wall components of an edible mushroom fruiting body from Pleurotus tuber regium (PTR) were fractionated and their chemical structures were investigated by chemical, physico-chemical and microscopic analyses. The present results suggest that cell wall of the PTR mushroom fruiting body contains four main fractions: an outer fraction of polysaccharide and protein complex which can be extracted using boiling water; a cold alkali-soluble fraction of heteropolysaccharides associated with small amount of proteins; a hot alkali-soluble fraction of hyper-branched glucans; and an alkali-insoluble fraction of glucan-chitin complex with a normalized relative percentage of 3.6 : 21.9 : 55.7 : 18.8. The anomeric linkage of all the glucans was revealed by infra-red spectroscopy to be beta type. The structure of the major mushroom fruiting body cell wall polysaccharide (the hot alkali-soluble one, FHA-I) was elucidated by the methylation analysis to be composed of →1)-Glcp-(4→ linkages as the backbone with a 52% degree of branching consisting of →1)-Glcp-(6→ linkages in the side chains, while some →1)-Glcp-(3→ linkages might exist in the backbone or side chains. Size exclusion chromatography coupled with multi-angle laser light scattering analysis revealed that FHA-I had a molecular weight of 4.224 × 10(6) g/mol and a root-mean-square radius of 30.4 nm. Both scanning electron and atomic force microscopy further showed that the highly-branched microstructure of FHA-I when dispersed in an aqueous sodium dodecyl sulfate solution.
    Journal of Agricultural and Food Chemistry 03/2014; 62(13):2891-2899. · 2.91 Impact Factor
  • Jinyang Zhao, Peter C K Cheung
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    ABSTRACT: Recent studies have demonstrated that β-glucans from different sources, which are considered as potential prebiotics, could enhance the growth of bifidobacteria. To elucidate the metabolic pathway of β-glucans in the widely used probiotic B. longumsubsp. infantis, a comparative proteomic analysis was carried out, along with two-dimensional difference gel electrophoresis (2D-DIGE), real-time RT-PCR and enzyme activity assay, on the samples obtained from cultures grown on β-glucans derived from barley, seaweed and mushroom. The results showed that 77 spots were found to be differentially expressed among different cultures, and 17 of them were predicted to play a role in β-glucan catabolism, including ABC transporter for sugars, enolase, and phosphotransferase system protein. Among them, 6 genes encoding for 6 proteins were shown to be induced by β-glucans at the transcriptional level and had higher abundance. The enzyme activity assay detected intracellular glucanase activity present in the cultures grown on the β-glucans from seaweed and mushroom. Based on the above results, a model for the catabolism of β-glucans in B. infantis is proposed as follows: The β-glucan molecules in the medium are transported into the cell through ABC (ATP-binding cassette) transport system and PTS (phosphotransferase system) proteins, followed by hydrolysis through the action of intracellular glucanase to glucose, which is subsequently incorporated into the central fermentative pathway 'bifid shunt'. This study for the first time reveals the possible degradation pathway of β-glucans by B. infantis, which has implications for the potential use of these β-glucans as novel prebiotics in the development of synbiotic application.
    Journal of Agricultural and Food Chemistry 04/2013; · 2.91 Impact Factor
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    Peter C.K. Cheung
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    ABSTRACT: Dietary fiber and high-fiber food products have attracted great attention because of their significant health benefits to consumers. Mushrooms are valuable resources for food, medicine and nutraceuticals. Edible mushroom is considered as a novel source of dietary fiber. The dietary fiber content and composition in edible mushroom vary greatly with its morphological stages including fruit body, mycelium and sclerotium. The focus of this mini-review is on the preparation of dietary fiber from edible mushroom with emphasis on the sclerotium which has the highest level of non-starch polysaccharides. The possible health benefits of mushroom dietary fiber in relationship with boosting the immune system, anticancer functions as well as the control of blood lipids and glucose levels are also discussed.
    Food Science and Human Wellness. 01/2013;
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    Bo-Bo Zhang, Lei Chen, Peter C K Cheung
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    ABSTRACT: Two-dimensional gel electrophoresis identified 40 differentially expressed proteins which explained the mechanisms underlying the stimulatory effect of Tween 80 for exopolysaccharide production in the mycelium of an edible mushroom Pleurotus tuber-regium. The up-regulation of fatty acid synthase alpha subunit FasA might promote the synthesis of long-chain fatty acids and their incorporation into the mycelial cell membranes, increasing the membrane permeability. A down-regulation of Phospholipase D1 and an up-regulation of Hypothetical protein PGUG_02954 might mediate signal transduction between the mycelial cells and the extracellular stimulus (Tween 80). The down-regulated ATP-binding cassette transporter protein might function as pumps to extrude exopolysaccharide out of the cells that lead to a significant increase in its production. The present results explained how stimulatory agents like Tween 80 can increase mycelial cell membrane permeability to enhance the production of useful extracellular metabolites by submerged fermentation.
    Journal of Agricultural and Food Chemistry 09/2012; · 2.91 Impact Factor
  • Bo-Bo Zhang, Lei Chen, Peter C K Cheung
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    ABSTRACT: Proteomic analysis was applied to investigate the mechanism of the stimulatory effect of Tween 80 on the mycelial growth and exopolysaccharide production by an edible mushroom Pleurotus tuber-regium. 32 differentially expressed proteins were identified by one-dimension gel electrophoresis. Combined with our previous findings, the up-regulation of heat shock proteins might help to maintain cellular viability under environmental stress. The up-regulation of ATP:citrate lyase isoform 2 could suppress the activity of tricarboxylic acid cycle and, consequently, stimulate exopolysaccharide production. The present results provide important insight to the mechanism by which stimulatory agents (Tween 80) can increase the production of useful fungal metabolites and also fill the gap of our knowledge on the under-developed mushroom proteomics.
    Biotechnology Letters 06/2012; · 1.85 Impact Factor
  • Bo-Bo Zhang, Lei Chen, Peter C K Cheung
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    ABSTRACT: Proteomic analysis was applied to investigate the mechanism of the stimulatory effect of Tween 80 on the mycelial growth and exopolysaccharide production by an edible mushroom Pleurotus tuber-regium. 32 differentially expressed proteins were identified by one-dimension gel electrophoresis. Combined with our previous findings, the up-regulation of heat shock proteins might help to maintain cellular viability under environmental stress. The up-regulation of ATP:citrate lyase isoform 2 could suppress the activity of tricarboxylic acid cycle and, consequently, stimulate exopolysaccharide production. The present results provide important insight to the mechanism by which stimulatory agents (Tween 80) can increase the production of useful fungal metabolites and also fill the gap of our knowledge on the under-developed mushroom proteomics.
    Biotechnology Letters 06/2012; · 1.85 Impact Factor
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    Lei Chen, Bo-Bo Zhang, Peter C K Cheung
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    ABSTRACT: Cell wall proteins (CWPs) play a vital role in the development of the different morphological stages including mycelium, fruiting body, and sclerotium in mushrooms which are important human food sources. Using fractionation by detergents and reducing agents, mushroom cell wall fractions from the different developmental stages of Pleurotus tuber-regium (PTR) were prepared. Using one-dimensional gel electrophoresis coupled with LC-MS, there were 103, 91, and 48 noncovalently linked CWPs identified in the cell wall fractions of the PTR mycelium, fruiting body, and sclerotium, respectively. Comparing the CWPs in these cell wall fractions, 19 of them were in common, among which 17 belonged to the functional categories of translation, ribosomal structure, and biogenesis. This is the first study to provide important biochemical insights into the different developmental stages of PTR mediated by CWPs, and the identified CWPs helped to explain the morphological changes of PTR mushrooms during cultivation.
    Journal of Agricultural and Food Chemistry 05/2012; 60(24):6173-82. · 2.91 Impact Factor
  • Lei Chen, Bo-Bo Zhang, Peter C K Cheung
    [Show abstract] [Hide abstract]
    ABSTRACT: Cell wall proteins (CWPs) play a vital role in the development of the different morphological stages including mycelium, fruiting body, and sclerotium in mushrooms which are important human food sources. Using fractionation by detergents and reducing agents, mushroom cell wall fractions from the different developmental stages of Pleurotus tuber-regium (PTR) were prepared. Using one-dimensional gel electrophoresis coupled with LC-MS, there were 103, 91, and 48 noncovalently linked CWPs identified in the cell wall fractions of the PTR mycelium, fruiting body, and sclerotium, respectively. Comparing the CWPs in these cell wall fractions, 19 of them were in common, among which 17 belonged to the functional categories of translation, ribosomal structure, and biogenesis. This is the first study to provide important biochemical insights into the different developmental stages of PTR mediated by CWPs, and the identified CWPs helped to explain the morphological changes of PTR mushrooms during cultivation.
    Journal of Agricultural and Food Chemistry 05/2012; 60:6173-6182. · 2.91 Impact Factor
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    ABSTRACT: The in vitro antitumor activities and in vivo immunomodulatory effects of water-soluble highly branched heteropolysaccharides isolated from Rhizoma panacis Japonici were evaluated by three cell lines and BALB/c mice implanted with Sarcoma 180 (S-180) tumors. The heteropolysaccharides showed potent tumor therapeutic effect by potentiating the animal's immune responses including an increase in white blood cell count and lymphocyte number. The heteropolysaccharides also induced apoptosis in the S-180 cells and alleviate the short-term side effect of cisplatin (DDP) to the animal during the treatment period. The bioactivity of the heteropolysaccharides might be due to their unique structures that had an α-(1 → 4)-d-glucan main chain with side chains containing mannose and galactose residues, a spherical chain conformation, as well as high water solubility, all of which facilitated their interaction with the surface receptors of the immune cells.
    Carbohydrate Polymers. 01/2012; 87(1):427-434.
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    Wenwen Xu, Jim Jun-hui Huang, Peter Chi Keung Cheung
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    ABSTRACT: Liver cancer or hepatocellular carcinoma is one of the leading causes of cancer-related deaths. Conventional chemotherapies are limited by the development of drug resistance and various side effects. Because of its non-toxicity and potent biopharmacological activity, metabolites derived from mushrooms have received more attention in cancer therapy. Our previous studies have demonstrated the anticancer effects of polysaccharide-protein complexes derived from the Pleurotus mushrooms. The aim of this study was to investigate the underlying molecular mechanism of the anticancer activity of a hot water extract containing a polysaccharide-protein complex isolated from Pleurotus pulmonarius (PP) in liver cancer cells. Our results indicated that exposure of liver cancer cells to PP not only significantly reduced the in vitro cancer cell proliferation and invasion but also enhanced the drug-sensitivity to the chemotherapeutic drug Cisplatin. Both oral administration and intraperitoneal injection of PP significantly inhibited the tumor growth in xenograft BALB/c nude mice. PP triggered a marked suppression of the PI3K/AKT signaling pathway in liver cancer cells in vitro and in vivo, and overexpression of the constitutively active form of AKT, Myr-AKT, abrogated this effect and the inhibited proliferation and invasion by PP. Both western blot and ELISA results showed that PP-treated liver cancer cells had reduced expression and secretion of vascular endothelial growth factor (VEGF). Addition of recombinant human VEGF attenuated the inhibitory effects of PP on PI3K/AKT pathway and the cancer phenotypes. Our results demonstrated that PP suppressed the proliferation, invasion, and drug-resistance of liver cancer cells in vitro and in vivo, mediated by the inhibition of autocrine VEGF-induced PI3K/AKT signaling pathway. This study suggests the potential therapeutic implication of PP in the treatment of human liver cancer.
    PLoS ONE 01/2012; 7(3):e34406. · 3.53 Impact Factor
  • Bo-Bo Zhang, Peter C K Cheung
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    ABSTRACT: Several new observations related to the enhancement effect of Tween 80 on the mycelial growth and exopolysaccharide production by the submerged fermentation of Pleurotus tuber-regium were reported in the present study. Firstly, it was found that the addition of Tween 80 on the 5th day could significantly increase the glucose consumption rate at the later stage of the fermentation compared to the control. Secondly, addition of Tween 80 could maintain the intact structure of the mycelial pellets of P. tuber-regium with little signs of disintegration as observed under microscope and kept the pH value of the fermentation broth at an acidic level lower than that of the control. Thirdly, the oleic acid (C18:1) composition in the mycelial cell membrane was significantly increased from 2.6% (in the control) to 18.5% (with addition of Tween 80) coincided with a decrease in the concentration of Tween 80 in the culture medium. These new findings provide some important insight to the elucidation of the detailed mechanism by which Tween 80 is used as a stimulatory agent in the submerged fermentation of mushroom mycelium.
    Bioresource Technology 06/2011; 102:8323–8326. · 5.04 Impact Factor
  • Bo-Bo Zhang, Peter C K Cheung
    [Show abstract] [Hide abstract]
    ABSTRACT: Several new observations related to the enhancement effect of Tween 80 on the mycelial growth and exopolysaccharide production by the submerged fermentation of Pleurotus tuber-regium were reported in the present study. Firstly, it was found that the addition of Tween 80 on the 5th day could significantly increase the glucose consumption rate at the later stage of the fermentation compared to the control. Secondly, addition of Tween 80 could maintain the intact structure of the mycelial pellets of P. tuber-regium with little signs of disintegration as observed under microscope and kept the pH value of the fermentation broth at an acidic level lower than that of the control. Thirdly, the oleic acid (C18:1) composition in the mycelial cell membrane was significantly increased from 2.6% (in the control) to 18.5% (with addition of Tween 80) coincided with a decrease in the concentration of Tween 80 in the culture medium. These new findings provide some important insight to the elucidation of the detailed mechanism by which Tween 80 is used as a stimulatory agent in the submerged fermentation of mushroom mycelium.
    Bioresource Technology 06/2011; 102(17):8323-6. · 5.04 Impact Factor
  • Jinyang Zhao, Peter C K Cheung
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    ABSTRACT: β-Glucans obtained from barley, seaweed, bacteria, and mushroom sclerotia were incubated with pure cultures of Bifidobacterium infantis, Bifidobacterium longum, and Bifidobacterium adolescentis for a 24 h batch fermentation to evaluate their bifidogenic effect with inulin as the positive control. The pH value in all culture media was decreased by 0.5-1.5 units. All β-glucans supported the growth of the three bifidobacteria with B. infantis, having a relatively larger increase in populations (3-4 log(10) colony forming units). B. infantis produced almost double the amount of total short-chain fatty acids (SCFAs) than the other two bifidobacteria. The SCFA profile of B. infantis had a relatively higher proportion of propionic and butyric acid but less acetic acid than the other bifidobacteria. The utilization of all the β-glucans isolated from different sources regardless of their differences in glycosidic linkages and molecular weight by all three bifidobacteria was comparable to that of inulin.
    Journal of Agricultural and Food Chemistry 05/2011; 59(11):5986-92. · 2.91 Impact Factor
  • Bo-Bo Zhang, Peter C K Cheung
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    ABSTRACT: Fatty acids, organic solvents and surfactants were investigated for their stimulatory effects on the growth of fungal mycelium and production of exopolysaccharide (EPS) by submerged fermentation of an edible mushroom Pleurotus tuber-regium. Addition of 3.0 g/L Tween 80 at the late stage of exponential growth phase provided the best stimulatory effect on mycelial biomass and fungal EPS production with a 51.3 and 41.8% increase, respectively. The chemical structure of the EPS produced with addition of Tween 80 was found to be a glucomannan with similar monosaccharide composition and glycosidic linkages but a significantly lower molecular weight (3.18 ± 0.09 × 10(6) Da), compared to the control (4.30 ± 0.12 × 10(6) Da). These two EPS could significantly inhibit the growth of chronic myelogenous leukemia K562 cells in a dose dependent manner, with an estimated IC(50) value of 43.7 and 47.6 μg/mL, respectively. The use of stimulatory agents to enhance production of bioactive fungal EPS can be applied in other fungal fermentation processes for enhancing production of useful metabolites.
    Journal of Agricultural and Food Chemistry. 02/2011; 59:1210-1216.
  • Bo-Bo Zhang, Peter C K Cheung
    [Show abstract] [Hide abstract]
    ABSTRACT: Fatty acids, organic solvents and surfactants were investigated for their stimulatory effects on the growth of fungal mycelium and production of exopolysaccharide (EPS) by submerged fermentation of an edible mushroom Pleurotus tuber-regium. Addition of 3.0 g/L Tween 80 at the late stage of exponential growth phase provided the best stimulatory effect on mycelial biomass and fungal EPS production with a 51.3 and 41.8% increase, respectively. The chemical structure of the EPS produced with addition of Tween 80 was found to be a glucomannan with similar monosaccharide composition and glycosidic linkages but a significantly lower molecular weight (3.18 ± 0.09 × 10(6) Da), compared to the control (4.30 ± 0.12 × 10(6) Da). These two EPS could significantly inhibit the growth of chronic myelogenous leukemia K562 cells in a dose dependent manner, with an estimated IC(50) value of 43.7 and 47.6 μg/mL, respectively. The use of stimulatory agents to enhance production of bioactive fungal EPS can be applied in other fungal fermentation processes for enhancing production of useful metabolites.
    Journal of Agricultural and Food Chemistry 02/2011; 59(4):1210-6. · 2.91 Impact Factor
  • Cuixia Guo, Ka-Hing Wong, Peter C K Cheung
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    ABSTRACT: Treatment of hot water extract of the sclerotium of Polyporus rhinocerus (PRW) with murine macrophages including RAW 264.7 cell line and primary macrophages (PMs) could enhance their functional activities. These include a significant up-regulation of pinocytosis; an increase in the production of reactive oxygen species (ROS) and nitric oxide (NO); an increase in tumor necrosis factor alpha (TNF-alpha) production and inducible nitric oxide synthase (iNOS) expression in both RAW 264.7 cells and PMs. Cell surface receptors for yeast-derived beta-glucan, including Dectin-1, CR3, and TLR2, were determined by flow cytometry, and the expression of Dectin-1+ cells on the cell surface decreased in the responses of PMs to PRW. PRW increased phosphorylation of IkappaBalpha, which could trigger the nuclear factor kappa B (NF-kappaB) signal pathway for macrophage activation in RAW 264.7 cells. Therefore, the immunomodulatory effect of PRW could be mediated by macrophage activation via the NF-kappaB signal pathway.
    International Journal of Medicinal Mushrooms 01/2011; 13(3):237-44. · 0.84 Impact Factor
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    ABSTRACT: Lentinan, a β-(1 → 3)-d-glucan isolated from a common edible mushroom, Lentinus edodes, is known as a biologically active macromolecules with very strong host-mediated anti-cancer activity, via activation of the human immune system. However, its widespread medicinal application is hindered by some technical difficulties in its extraction and purification, as well as a lack of thorough understanding of the structure-and-function relationship of this polysaccharide. This review aims at highlighting the different areas of research conducted on lentinan in the past 40 years, including its extraction and purification processes, the analysis of structure, the determination of its chain conformation and conformation transition in solution, as well as its rheological properties and bioactivities especially on anti-cancer treatment. About 156 literatures were cited to summarize the advancement of lentinan in the review paper.
    Food Hydrocolloids - FOOD HYDROCOLLOID. 01/2011; 25(2):196-206.

Publication Stats

1k Citations
142.00 Total Impact Points

Institutions

  • 1996–2014
    • The Chinese University of Hong Kong
      • • School of Life Sciences
      • • Department of Biology
      Hong Kong, Hong Kong
  • 2012
    • Jiangnan University
      • School of Biotechnology
      Wuxi, Jiangsu Sheng, China
  • 2004–2010
    • Wuhan University
      • Department of Chemistry
      Wuhan, Hubei, China
    • JiangHan University
      Jiang’an, Hubei, China