| Dendrobium huoshanense GZ.Tang et S. J. Cheng is a rare precious Chinese herb. It has been in severe danger. In order to realize its sustainable utilization by mass propagation of protocorm-like bodies (PLBs) in bioreactor, culture conditions influencing proliferation and polysaccharide accumulation of PLBs were investigated in this paper. Furthermore, the health care efficacy of PLBs was evaluated .1) The most suitable basal medium for proliferation of PLBs in liquid culture system was basal MS at half-strength. Through one-factor and orthogonal tests, the optimum organic additives and plant regulators was obtained. The optimized medium, where the proliferation multiple of PLBs reached 12.56 after 40 days of culture, was 1/2MS supplemented with 30 g L-1 sucrose, 100 g L-1 potato extract, 30 g L-1 banana extract and 1.0 mg L-1 IBA.2) The regulation for growth and polysaccharide synthesis of PLBs by adding glucose and sucrose to medium respectively showed that sucrose responded better for polysaccharide accumulation. MS medium at half-strength containing 150 g L-1 potato extract, 30 g L-1 banana extract, 30 g L-1 sucrose was suitable for polysaccharide accumulation and 9.78 mg polysaccharides per gram PLBs was obtained within 30 days. There is a negative correlation between polysaccharide accumulation and growth of PLBs by Pearson's correlation analysis, the correlation coefficient was -0.845.3) The activity of polysaccharides from D. huoshanense PLBs that lessen eye tiredness and improve immune function in mice treated with cyclophosphamide (CY) was evaluated. Experiments showed that when the beverage prepared by mixing D. huoshanense PLBs and tea in 7:3 (w/w) ratio was given to mice, the activity of SOD in eyes and blood serum were significantly enhanced 1.64 times and 1.47 times and the organ indexes were improved. Compared to CY group, the spleen index and thymus index of the beverage group were 21.6% and 79.0% respectively.
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