Study On The Dynamic Accumulation Of Nutrients In Dendrobium Huoshanense And The Anti-tumor Activity Of Its Polysaccharides

Dendrobium huoshanense is a perennial medicinal and edible herb,which is only distributed in Dabie mountains in Anhui province.Its edible history is more than 300years.In order to develop Dendrobium huoshanense into new food material,the main nutritional components and physiological active components including physicochemical properties and anti-tumor activities of polysaccharides in its edible part?stems?were studied in this paper.The main results obtained were as follows:?1?The stem of Dendrobium huoshanense contains all nutrients in food materials.In the 12 months of the year,the contents of soluble protein,total protein,free amino acids,total amino acids as well as free essential amino acid,total essential amino acids,free no-essential amino acid and total no-essential amino acids ranged between3.15⁹.23 mg/100 g,6.75¹0.11%,10.1¹3.2 mg/g,47.2⁶7.6 mg/g,1.4².6 mg/g,14.2¹8.7 mg/g,7.5¹1.7 mg/g and 33⁴8.9 mg/g,respectively.The stem of Dendrobium huoshanense also contains abundant mineral substances,vitamin E,vitamin B₁,vitamin B₂ and dietary fiber,and their contents ranged between2822.97⁴479.32 mg/kg,2.14⁷.72 mg/100 g,0.093⁰.239 mg/100 g,0.257⁰.485mg/100 g and 32.67³7.48%during 12 months of one year.Beside free essential amino acids and vitamin B1,the contents of other nutritional components tested showed a similar change of decreasing from February,increasing from April and May and reaching the peak between June and July followed by a continuous decrease and a subsequent rise.?2?The polysaccharides and ethanol extracts,the main active components of Dendrobium huoshanense stems,showed strong regular changes during 12 months throughout the year.The content of polysaccharide in spring and summer was higher than in autumn and winter,and its content ranged between 14.90³4.58%with an annual mean of 21.23%.The content of ethanol extracts was higher in autumn and winter than in spring and summer,and its content ranged between 10.59²9.25%with an annual mean of 20%.?3?The analysis of physicochemical properties showed that the average molecular weight of polysaccharide from stem of Dendrobium huoshanense was 1.74×10⁵ Da,and the polysaccharide components from May to September were relatively homogeneous.The average viscosity of polysaccharide was 0.44 dl/g.The average annual contents of acetyl group and uronic acid were 3.27%and 5.03%,respectively;The uronic acid content was maximum in October?4.22%?and kept around 3.20%in the other months.The content of acetyl group decreased continuously from February to May,reached the lowest level in May?4.20%?and from May to September it was increased continuously to 5.63%.The monosaccharide composition analysis showed that the polysaccharide of Dendrobium huoshanense stem was mainly composed of mannose and glucose,and their molar ratio was between 2.83⁵.84 with an average molar ratio of 4.20 and an average mannose content of 80.15%.?4?In vitro anti-tumor experiments showed that polysaccharides from Dendrobium huoshanense stem,which was collected at different months of year,had a certain inhibitory effect on the growth of gastric cancer,esophageal cancer and colorectal cancer cell.Polysaccharide from stems collected in August showed the best inhibition effect on the colorectal cancer cells and the inhibition rate was 45.62%.In conclusion,the stem of Dendrobium huoshanense contained abundant nutritional compositions,not only rich in essential amino acids,trace elements and vitamin E,but also having high content of active polysaccharides.The research on the contents of nutrients and active ingredients as well as physicochemical properties and biological activities of Dendrobium huoshanense stem could provide scientific basis for the application of new food material and the establishment of relevant food safety standards,and lay a theoretical foundation for the research and development of functional food of Dendrobium huoshanense.