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November 2010

[Competitive effect of PSK against the immunosuppressive effect induced in the sera of mice bearing syngeneic tumors]

PSK is a protein-bound polysaccharide prepared from cultured mycelium of Coriolus versicolor. The appearance of an immunosuppressive effect in sera of tumor-bearing mice and its elimination by oral administration of PSK were investigated using an in vitro assay of blastoid transformation of normal spleen cells in response to PHA. (1) An inhibitory effect appeared in sera of X5563 plasmacytoma-bearing mice, while a facilitating effect was noted in sera of MH134 hepatoma- and MM 102 mammary tumor-bearing mice. (2) The presence of both an inhibitory and a facilitating factor was shown by Sephacryl gel fractionation. (3) Oral administration of PSK resulted in the elimination of the inhibitory effect from sera of X5563-bearing mice. The facilitating effect of sera from MH134-bearing mice was augmented by PSK administration, but that in sera from MM102-bearing mice was not influenced by such treatment. The summarized effects of these factors may be expressed as various types of effects in serum and PSK may be effective in the elimination of a suppressive factor from such sera.[…]

[Restoration of immunologic responsiveness by PSK in tumor-bearing animals]

PSK is a protein-bound polysaccharide prepared from cultured mycelium of the Basidiomycete Coriolus versicolor. Effects of PSK on the immunologic responsiveness in tumor-bearing animals were investigated using syngeneic or allogeneic tumors in mice (Lewis lung carcinoma, B16 melanoma, Meth A fibrosarcoma, adenocarcinoma 755, X5563 plasmacytoma, colon 26, MOPC 31C myeloma, sarcoma 180 and Ehrlich carcinoma), rats (BC47 bladder carcinoma, Walker 256 sarcoma and AH7974 hepatoma), hamsters (HA-1T tumor and RPMI 1846 melanoma), guinea pigs (line-10 hepatoma) and rabbit (VX2 and VX7 tumor). Oral or intraperitoneal administration of PSK restored the depressed delayed hypersensitivity against sheep erythrocytes to a normal level in these tumor-host systems. Also, oral administration of PSK lowered the activity of immunosuppressive substances in the serum of tumor-bearing animals. These results suggest that PSK exhibits antitumor effects by restoring the depressed immunologic responsiveness in tumor-bearing animals.[…]

Effect of immunostimulants and antitumor agents on tumor necrosis factor (TNF) production.

OK-432, a lyophilized preparation of Streptococcus pyogenes, showed a priming activity for TNF production in mice, associated with an increase of spleen weight. PSK, a protein-bound polysaccharide preparation from Coriolus versicolor, did not show such activity. Both OK-432 and PSK potentiated the TNF production in mice primed with Corynebacterium parvum (CP) and challenged with Escherichia coli endotoxin (LPS). Cytotoxic antitumor agents of 5-fluorouracil (5-FU), cyclophosphamide (CY) and bleomycin (BLM) suppressed TNF production in mice primed with CP and challenged with LPS. TNF production suppressed by 5-FU, CY and BLM was partially restored by the combined treatment with OK-432 or PSK. These results suggest that the administration of cytotoxic antitumor agents suppresses the intrinsic TNF production in cancer patients, and the combined use of immunostimulants such as OK-432 and PSK is advantageous in restoring TNF production suppressed by cytotoxic antitumor agents.[…]

Effect of PSK on prohibited immunity of splenectomized mice.

The effect of PSK (Krestine, an anti-tumor drug prepared from Coriolus versicolor) on splenectomized experimental animals was investigated. Splenectomy was performed on both a tumor-free control group and a tumor-bearing group. The administration of PSK on the splenectomized control group significantly increased the immune state of the host. In the case of the tumor-bearing group, administration of PSK resulted in restoration of the immune function as observed in the control group. Recovery of the immunological function was accelerated when tumor-bearing animals were splenectomized at the terminal stage. The results suggest that the immunomodulating effects of PSK developed at the time of the splenectomy resulted in anticancer activity.[…]

Combined submerged and solid substrate fermentation for the bioconversion of lignocellulose.

A novel two-stage bioreactor has been designed for a combined submerged (SF) and solid substrate fermentation (SSF) of wheat straw. The straw was pretreated with steam, and cellulases from the culture fluid of Trichoderma reesei were adsorbed on it for increased bioconvertibility. SSF was conducted in the top part of the bioreactor by inoculating the straw with a 36-h mycelial culture of T. reesei, or Coriolus versicolor. In the bottom part of the fermenter, Endomycopsis fibuliger was grown in SF. The SF liquor was recirculated through the SSF stage at 24 h intervals to remove glucose and other metabolites that may inhibit growth, and to maintain optimum moisture level and temperature. The removed glucose and other metabolites provided nutrients for the yeast in the SF stage. The combined fermentation resulted in overall higher biomass yield, increased bioconversion, increased cellulase production, and increased digestibility compared with single SSF or SF.[…]

Restoration of immune responsiveness by a biological response modifier, PSK, in aged mice bearing syngeneic transplantable tumor.

PSK (Krestin) is a protein-bound polysaccharide isolated from cultured mycelia of Coriolus versicolor in basidiomycetes. PSK is a biological response modifier which possesses unique characteristics. We investigated the effects of PSK on the immune response of aged C57BL/6 mice bearing a syngeneic transplantable tumor adenocarcinoma 755. (a) In C57BL/6 mice, the delayed foot pad reaction against sheep erythrocytes and resistance to syngeneic tumor challenge reached a peak when the mice were at 30 weeks of age, and decreased at 50-60 weeks of age. The serum of normal mice exerts a modifying effect on blastogenesis of lymphocytes to phytohemagglutinin. The positive effect reached a peak at 30 weeks of age, and thereafter declined with age. (b) When adenocarcinoma 755 was inoculated to C57BL/6 mice at 10-, 30- and 60-weeks of age, immune responses were depressed in 10-week-old and 60-week-old mice. PSK prevented such depression. However, in 30-week-old mice, tumor-induced suppression was slight, and administration of PSK to them increased proportion of mice which did not develop a tumor. (c) In 60-week-old tumor-bearing mice, the antitumor effects was increased with a combination of PSK and adoptive transfer of spleen cells from 10-week-old normal mice. The immune responses of mice, which change with the progress of age, are depressed by tumor burden. The administration of PSK to aged mice is effective to restore immune responses from tumor-induced suppression.[…]

Solubilization of Leonardite by an Extracellular Fraction from Coriolus versicolor.

Coriolus versicolor has previously been shown to degrade leonardite, an oxidized form of lignite. An extracellular fraction containing protein purified from a C. versicolor culture solubilized leonardite in vitro. Expression of the activity did not require the presence of leonardite and appeared during idiophase. During ion-exchange and gel filtration column chromatography, leonardite-biosolubilizing activity eluted with syringaldazine oxidase activity and with protein, as measured by A(280) and the biuret protein assay. Syringaldazine is a substrate of the polyphenol oxidase formed by C. versicolor. Comparison of leonardite-biosolubilizing activity with the effects of chelators and surface-active agents on leonardite showed that biosolubilization was not due to either surfactant or chelating ability. Heat treatment of the preparation at 60 degrees C for 30 min significantly reduced both syringaldazine oxidase and leonardite-biosolubilizing activities. Cyanide, azide, and thioglycolate, which are known inhibitors of syringaldazine oxidase activity of C. versicolor, also inhibited leonardite biosolubilization. From these data, we conclude that the purified protein fraction from C. versicolor contains a syringaldazine oxidase activity that participates in leonardite biosolubilization by enzymatic action.[…]

Electron paramagnetic resonance studies of type 1 copper in type 2 depleted fungal laccase A.

The electron paramagnetic resonance (EPR) spectra of type 1 copper(II) in 63Cu-enriched Coriolus versicolor laccase A (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) have been studied. The X-band EPR spectrum in type 2 copper-depleted [63Cu]laccase A exhibited well-resolved ligand superhyperfine structure in the g perpendicular region. This structure was assigned to an interaction with two nitrogens and two protons, an assignment which is consistent with a model in which the two nitrogens belong to two histidine ligands and the two protons are the methylene protons of a coordinating cysteine. It also requires the delocalization of a substantial amount of the type 1 copper(II) unpaired electron density onto the cysteine sulphur.[…]

Effect of PSK, a protein-bound polysaccharide from Coriolus versicolor, on drug-metabolizing enzymes in sarcoma-180 bearing and normal mice.

The effects of PSK and Propionibacterium acnes (anaerobic Corynebacterium) on hepatic drug-metabolizing enzymes were studied using sarcoma-180 bearing and non-tumor bearing mice. PSK had no influence on aminopyrine N-demethylase and aniline hydroxylase activities, cytochrome P-450 concentration in hepatic microsomes, and the reductase activity of cytochrome c in normal mice. The content of cytochrome P-450 was not significantly reduced in S-180 bearing mice. On the other hand, P. acnes administration significantly decreased the amount of cytochromes P-450 and b5 and aminopyrine N-demethylase activity. When FT-207 (Tegafur) was administered orally to S-180 bearing mice combined with the immunoadjuvants, only P. acnes significantly reduced the 5-FU levels in the serum and some organs.

Degradation mechanisms of phenolic beta-1 lignin substructure model compounds by laccase of Coriolus versicolor.

Phenolic beta-1 lignin substructure model compounds, 1-(3,5-dimethoxy-4-hydroxy-phenyl)-2-(3,5-dimethoxy-4-ethoxyphenyl)propa ne-1, 3-diol (I) and 1-(3,5-dimethoxy-4-ethoxyphenyl)-2-(3, 5-dimethoxy-4-hydroxyphenyl)propane-1,3-diol (II) were degraded by laccase of Coriolus versicolor. Substrate I was converted to 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-(3,5-dimethoxy-4-ethoxyphenyl)-3- hydroxypropanone (III), 1-(3,5-dimethoxy-4-ethoxyphenyl)-2-hydroxyethanone (IV), syringaldehyde (V), 1-(3,5-dimethoxy-4-ethoxyphenyl)-3-hydroxypropanal (VI), 2,6-dimethoxy-p-hydroquinone (VII), and 2,6-dimethoxy-p-benzoquinone (VIII). Furthermore, incorporations of 18O of 18O2 into ethanone (IV) and 18O of H218O into hydroquinone (VII) and benzoquinone (VIII) were confirmed. Substrate II gave 1-(3,5-dimethoxy-4-hydroxyphenyl)ethane-1, 2-diol (IX), 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-hydroxyethanone (X), and 3,5-dimethoxy-4-ethoxybenzaldehyde (XI). Also 18O of H218O was incorporated into glycol (IX) and ethanone (X). Based on the structures of the degradation products and the isotopic experiments, it was established that three types of reactions occurred via phenoxy radicals of substrates caused by laccase: (i) C alpha-C beta cleavage (between C1 and C2 carbons); (ii) alkyl-aryl cleavage (between C1 carbon and aryl group); and (iii) C alpha (C1) oxidation.[…]