Studies On Anti-oxidation And Anti-aging Of Polysaccharides From Eight Dendrobium Species

Dendrobium is the second largest genus in orchid and have 80 kinds distributed in our country, many of which are of medicinal Dendrobium. It is a valuable Chinese traditional medicine with world-famous. With the China's economy and people's living standards developing, the demand for flowers is more and more extensive. Dendrobium, as an enjoyment and food dual-purpose flower, has a wide range of application and attracts more and more attention. As the market of Chinese herbal medicine, mainly in Dendrobium, is gradually heating up, Dendrobium's application in commodity come to fashion as well. Due to the large amount of species within Dendrobium and their complicated chemical components, the research progress on its relative chemical components and pharmacological effect is made slowly. There are few studies on different activity between different Dendrobium, while the anti-aging and antioxidant study using the model organism of Caenorhabditis elegans is almost a blank. This study bases on medicinal Dendrobium——Dendrobium officinale Kimura et Migo, Dendrobium cucullatum R. Br. ex Lindl, Dendrobium loddigesii Rolfe, Dendrobium chrysanthum Wall. ex Lindl, Dendrobium thyrsiflorum Rchb., Dendrobium nobile, Dendrobium chrysotoxum Lindl., and Dendrobium moniliforme?L.? Sw. and did a series of anti-aging and antioxidant research on the model organism Caenorhabditis elegans. The main results are as follows:1. Study on the content and molecular weight of the polysaccharide of Dendrobium. Using the eight Dendrobium varieties in spring as materials and comparing their differences in polysaccharide contents, we found that the water contents of eight Dendrobium are between 58.69%⁹1.59% with significant difference. The contents of polysaccharide differs in the eight Dendrobium widely followed by D. officinale?43.83%? > D. loddigesii?36.47%? > D. chrysanthum?31.8%? > D. nobile ?30.58%? > D. cucullatum?21.97%? > D. chrysotoxum?19.66%? > D. moniliforme?19.21%? > D. thyrsiflorum?15.93%?.The compared research of the average molecular weight, D. chrysotoxum has five elution peaks, D. nobile has four elution peaks, D. chrysanthum and D. loddigesii have two elution peaks, and the rest all have three elution peaks. In addition, the components of maximum of molecular weight are all from D. thyrsiflorum?average molecular weight: 1.4*1011 Da, 17.83%? and the components of minimum of molecular weight are all from D. nobile?average molecular weight: 1570 Da, 8.83%?. Remaining higher proportion of Dendrobium polysaccharides typically distribute tens of thousands of molecular weight to hundreds of thousands of molecular weight.2. Study on the antioxidant activity in vitro of Dendrobium polysaccharides. This research selected reducing force system, DPPH free radical scavenging system, ABTS method determination system of total antioxidant capacity, lipid peroxidation inhibition system, scavenging ?OH free radical system, metal ion chelate system, in vitro gastric fluid removal of NO₂^- system and in vitro antioxidant activity study. Results show that: Dendrobium polysaccharides have antioxidant capacity in different antioxidant system with significant and relative dose effect, but different antioxidant capacities occur in different systems significantly. Dendrobium chrysotoxum Lindl. shows the best in reducing force system, DPPH free radical scavenging system. Dendrobium officinale Kimura et Migo has the best effect in metal ion chelate system, which was significantly higher than that from other Dendrobium. Dendrobium nobile has the best capacity in the removal of NO₂^- and hydroxyl free radical, but has little difference from the other Dendrobium, Dendrobium chrysanthum Wall. ex Lindl has a maximum inhibition on lipid oxidation.3. Study on 3 kinds of Dendrobium polysaccharide, Dendrobium officinale Kimura et Migo, Dendrobium moniliforme?L.? Sw. and Dendrobium chrysotoxum Lindl, of delaying Caenorhabditis elegans aging. Result shows that Dendrobium polysaccharide could significantly prolong the life of C. elegans with the best effect of 80.0 mg/L polysaccharide of Dendrobium chrysotoxum Lindl. Dendrobium polysaccharide has no significant bad influence in the reproductive capability of C. elegans, but shows the ability to strengthen their exercise ability and the capacity of stress resistance with concentration dependence.