Characterization and Bioactivity Analysis of Dendrobium officinale Stem and Leaf Polysacchride

Abstract:

Dendrobium officinale is a precious medicinal plant containingmany bioactive compounds and its stem was the main subject for structure and bioactivity research. In this study，the types and contents of active compounds in D. officinale stem and leaf were compared. Although D. officinale stem and leaf had similar compounds，the content of polysaccharide and dendrobine in stem was 2.71 and 3.02 times as high as in leaves，while the content of fat-soluble composition and crude protein in leaves was significantly higher than that in stem. After monosaccharide composition analysis of purified stems and leaves polysaccharide，D. officinalestem polysaccharide（DOSP） was composed of mannose and glucose with mole ratio of 3.07：1. However，D. officinale leaf polysaccharide（DOLP） mainly contained mannose，glucose，galactose and arabinose with mole ratio 8.81∶1∶0.57∶0.37. In addition，the intrinsic viscosity and of DOSP was 56.26 dL/g and DOLP was 8.05 dL/g，while the corresponding molecular weight of DOSP and DOLP were 1 207 000 and 318 000，respectively. The results of free radical scavenging capacity shows that DOLP has higher DPPH free radical scavenging capacity than DOSP indicating a high potential for applied as theantioxidant. Finally the extracted condition of DOSP and DOLP was optimized by comparing various temperatures，extracted times and solid-liquid ratio to enhance the yield of this active compound.