Molecular Modification of Polysaccharides and Resulting Bioactivities.

Polysaccharides are ideal natural resources for supplements and pharmaceuticals that have received more and more attention over the years. Natural polysaccharides have been shown to have fewer side effects, but because of their inherently physicochemical properties, their bioactivities were difficult to compare with those of synthetic drugs. Thus, researchers have modified the structures and properties of natural polysaccharides based on structure-activity relationships and have obtained better functionally improved polysaccharides. This review focuses on the major modification methods of polysaccharides, and discusses the effect of molecular modification on their physicochemical properties and bioactivities. Molecular modification methods mainly include chemical, physical, and biological changes. Chemical modification is the most widely used method; it can significantly increase the water solubility and bioactivities of polysaccharides by grafting onto other groups. Physical and biological modifications only change the molecular weight of a polysaccharide, and thereby change its physicochemical properties and bioactivities. Most of the molecular modifications bring about an increase in the antioxidant activity of polysaccharides, and among these, sulfated and acetylated modifications are very common. Furthermore, phosphorylation modification is the most common application to increase antitumor activity, and modified polysaccharides have been shown to have anti-HIV activity as the result of sulfated modification.

Photodynamic action of methylene blue in osteosarcoma cells in vitro.

BACKGROUND: Osteosarcoma is a common malignant bone tumor which threatens the life of young people worldwide. To explore alternative strategy for combating osteosarcoma, a light-emitting diode (LED) that activates methylene blue (MB) was used in the present study to investigate cell death of osteosarcoma-derived UMR106 cells. MATERIALS AND METHODS: Photocytotoxicity in UMR106 cells was investigated 24h after photodynamic activation of MB using sulforhodamine B (SRB) assay and light microscopy. Apoptosis induction was observed 24h after photodynamic treatment using a confocal laser scanning microscopy (CLSM) with Hoechst 33342 staining. The change in mitochondrial membrane potential (MMP) was analyzed using a flow cytometry with rhodamine 123 staining. RESULTS: MB under red light irradiation caused a drug-concentration (0-100µM) and light-dose (0-32J/cm(2)) dependent cytotoxicity in UMR106 cells. The SRB assay and light microscopy observed a significant decrease in the number of UMR106 cells attached to the bottom of culture well after LED light-activated MB (100µM, 32J/cm(2)). Nuclear shrinkage, chromatin condensation and fragmentation were found in the treated cells by nuclear staining. In addition, flow cytometry showed that the MMP in UMR106 cells was rapidly reduced by photo-activated MB (100µM, 32J/cm(2)). CONCLUSION: Photodynamic action of MB under LED irradiation could remarkably kill osteosarcoma cells and induce cell apoptosis as well as MMP collapse.

[Study on PLB induction and proliferation of Dendrobium officinale].

OBJECTIVE: To study on the optimal medium ingredients for PLB induction and proliferation of Dendrobium officinale. METHODS: Seed embryos of Dendrobium officinale were cultivated in MS medium as the basic medium, along with different plant hormones like 6-BA, NAA,2,4-D and KT or their combinations added with organic additives like PE, BE, AE and CM. RESULTS: BA and NAA combination was not conductive to germination and the germination ratio was even lower than that of MS medium; 10% PE and CM was beneficial to PLB induction; 2,4-D was not conductive to growth and proliferation; A certain concentration of BA, KT and NAA was beneficial to PLB proliferation; KT at 1.0 mg/L recorded the highest 40 d PLB proliferation times at 9.0; PE, CM and AE could promote the PLB proliferation at different levels, among which 10% CM was the most effective. CONCLUSION: The optimized medium ingredients suitable for PLB induction are MS +10% CM +1.0g/L AC; The optimized medium ingredients suitable for PLB proliferation are MS + 1.0 mg/L KT + 0.2 mg/L NAA + 10% CM.