ABSTRACT
A novel water-soluble polysaccharide IP3a was successfully isolated and purified from I. obliquus by DEAE-cellulose, Sepharose CL-6B and Sephadex G-200 column chromatography. Chemical characterization and antitumor and immunoregulatory activity of IP3a were investigated. IP3a consisted of rhamnose, arabinose, glucose and galactose in a molar ratio of 2.5:4.6:1.0:2.6 with an average molecular weight of 48,820 Da. IP3a exhibited no significant antitumor activities in vitro. However, IP3a could not only inhibit the growth of transplantable Jurkat tumor in mice significantly, but also could enhance the splenocyte proliferation and lymphocyte proliferation induced by ConA and LPS in a dose-dependent manner. At the same time, IP3a could promote cytokine secretion (IL-2, IL-6, IL-12 and TNF-α) and macrophage phagocytosis in mice. In addition, IP3a could increase Bax expression and inhibit Bcl-2 expression significantly. These results suggested that antitumor mechanisms of IP3a might be associated with improving immune response in vivo and inducing apoptosis of tumor cells in vitro. IP3a might be utilized as a potential therapeutic agent against lymphoma cancer with immunomodulatory activity.
Subject(s)
Antineoplastic Agents/pharmacology , Basidiomycota/chemistry , Fungal Polysaccharides/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/isolation & purification , Cell Proliferation/drug effects , Cytokines/blood , Female , Fungal Polysaccharides/chemistry , Fungal Polysaccharides/isolation & purification , Humans , Jurkat Cells , Macrophages/drug effects , Macrophages/physiology , Male , Phagocytosis/drug effects , Proto-Oncogene Proteins c-bcl-2/metabolism , Xenograft Model Antitumor AssaysABSTRACT
Defatted soybean flour was treated with hexane and ethanol to reduce lipid content and heated to inactivate lipoxygenase (LOX, linoleate:oxygen reductase; EC 1.13.11.12) to obtain lipid-reduced soybean flour (LRSF). The effects of processing conditions such as pH, reducing agent and storage time on yields and purity of glycinin (11S) were evaluated in the fractionation of soybean glycinin isolated from LRSF. Adjusting the pH of protein extract from 6.2 to 6.6, the yield of glycinin decreased by 16.71%, while the purity of the protein increased by 4.60%. Sulfhydryl and disulfide content of proteins increased by degrees with increasing pH. Compared with dithiothreitol (DTT) or ß-mercaptoethanol (ME) as reducing agent, the yield of glycinin was the highest when sodium bisulfite (SBS) was added to the protein extract at pH 6.4. The effect of DTT on yields of glycinin was the lowest of the three kinds of reducing agent. The purity of glycinin was similar when the three kinds of reducing agent were used. These results showed that SBS was the best choice for the isolation of 11S-rich fraction. Prolonging storage time in the precipitation stage, 10 h was the best for yields and purity of glycinin in the experiment, while there was no significant difference at P ≥ 0.05 for total sulfhydryl and disulfide content. The decreased free sulfhydryl content of glycinin indicated that the oxidation of free sulfhydryls and the formation of disulfide bonds occurred when the extraction time was prolonged.
Subject(s)
Globulins/isolation & purification , Glycine max/chemistry , Lipids/chemistry , Plant Extracts/isolation & purification , Soybean Proteins/isolation & purification , Disulfides/chemistry , Dithiothreitol/chemistry , Globulins/chemistry , Hydrogen-Ion Concentration , Mercaptoethanol/chemistry , Oxidation-Reduction , Plant Extracts/chemistry , Reducing Agents/chemistry , Solid Phase Extraction , Solubility , Soybean Proteins/chemistry , Sulfhydryl Compounds/chemistry , Sulfites/chemistryABSTRACT
Effects of lipoxygenase I-B (LOX)-catalyzed oxidation of linoleic acid on soybean proteins was evaluated by electron spin resonance (ESR) and fluorescence spectroscopy in different model systems in the presence or absence of antioxidants. A strong central singlet signal was detected by ESR spectroscopy and identified as the carbon radical (g value range 2.0041-2.0054). A downfield shoulder attributed to the sulfur radical (g value 2.019-2.028) was also observed. The changes in soybean proteins were accompanied by an increase in fluorescence, indicating the formation of cross-links. Natural antioxidants such as ascorbic acid and alpha-tocopherol as well as synthetic antioxidants butyl hydroxytoluene (BHT) inhibited the development of both the free radical signal and the fluorescence when added to soybean proteins prior to incubation with linoleic acid and lipoxygenase I-B; the central singlet signal attributed to the carbon radical was reduced by 35-65%. This paper clearly indicates direct free radical transfer from oxidizing linoleic acid catalyzed by LOX to soybean proteins.
