Comparative study on three polysaccharides from Dendrobium officinale and their hypoglycemic activity
Diabetes is a major chronic disease in today’s society, which is generally divided into type I and type II, the latter accounting for about 90%, and the main feature is hyperglycemia. Long term hyperglycemia will increase the functional burden of tissues and organs, especially vascular injury, which will induce a variety of acute and chronic diseases. Reducing blood sugar is the key to the treatment of diabetes. Clinical hypoglycemic drugs such as insulin analogues, sulfonylureas, biguanides, thiazolidinones, etc. have significant effects but often cause side effects. Developing safe and reliable hypoglycemic drugs has become a research hotspot.

Many studies have found that natural polysaccharides have hypoglycemic activity. As a traditional Chinese medicine prescription for diabetes, astragalus polysaccharide is the main active ingredient. In vitro studies show that astragalus polysaccharide (APS) stimulates the glucose uptake of L6 myotubes through AMP-AMPK-AS160 pathway to reduce blood sugar levels. The traditional Chinese dietary supplement wolfberry, which has hypoglycemic activity, has been studied to promote pancreatic islet cell proliferation and insulin secretion through polysaccharides, achieving the effect of lowering blood sugar. In addition, polysaccharides from many plants such as Ophiopogon japonicus, Ganoderma lucidum, Angelica sinensis, and ginseng also have hypoglycemic activity. It is generally believed that natural polysaccharides mainly promote an increase in insulin levels and a decrease in glucagon levels in plasma; Improve insulin sensitivity; Inhibit glycosidase activity in the digestive system; Protect pancreatic islet cells and other mechanisms to achieve blood glucose reduction. Natural polysaccharides provide abundant resources for the development of hypoglycemic drugs.

Dendrobium, as a traditional precious medicinal herb and nourishing yin product, polysaccharides are its main bioactive substances. The 2015 edition of the pharmacopoeia includes four types of dendrobium, namely Dendrobium officinale, D. nobile, D. chrysotoxum, and D. fimbriatum, for medicinal use. Research shows that D. huoshanense polysaccharide can effectively reduce the blood sugar content of diabetes rats. Dendrobium nobile polysaccharide has significant hypoglycemic effect on alloxan induced diabetes mice. In addition, some scholars found that the polysaccharides of Dendrobium nobile, Dendrobium candidum and Dendrobium huoshanense could significantly reduce the blood sugar of alloxan induced diabetes mice. The dendrobium polysaccharide resources for lowering blood sugar have significant development value.

In order to find a more economical natural polysaccharide Dendrobium, this article compared and analyzed the polysaccharide content of various Dendrobium plants. It was found that the traditional Yunnan medicinal herb, Dendrobium grandiflorum (Tengchong Dendrobium), has a high yield and a stem weight of 3-5 times that of Dendrobium officinale. Its polysaccharide content is comparable to that of Dendrobium officinale (38%, DW), making it an excellent polysaccharide plant with potential development value. On the basis of existing research, this article analyzes the chemical characteristics and hypoglycemic activity of polysaccharides from Dendrobium officinale, and compares them with traditional Dendrobium officinale and Dendrobium nobile, providing a theoretical basis for the development of hypoglycemic polysaccharides

Polysaccharides are the main medicinal components of Dendrobium officinale, which belongs to the same group as Dendrobium officinale and Dendrobium nobile in the pharmacopoeia. Comparison shows that the yield of polysaccharides in Dendrobium officinale is 1.5 times that of Dendrobium officinale and 3.42 times that of Dendrobium nobile, while the polysaccharide content is comparable to that of Dendrobium officinale, indicating great potential for development. In the structure-activity relationship of active polysaccharides, molecular weight and monosaccharide composition are two key structural information that affect the biological activity of polysaccharides; The size of molecules is a necessary condition for polysaccharides to possess biological activity and is the basis for the formation of advanced structures. It is generally believed that the molecular weight of polysaccharides is related to immune activity. The molecular weight of polysaccharides from Dendrobium officinale is smaller than that of Dendrobium officinale and Dendrobium nobile, but still between 3.2 and 59 kDa, which have been reported as hypoglycemic plant polysaccharides. The antioxidant activity of natural polysaccharides is mainly determined by the composition of monosaccharides, and the antioxidant activity of polysaccharides is a mechanism of action in lowering blood sugar; The monosaccharide composition of Dendrobium officinale polysaccharides is basically the same as that of Dendrobium officinale polysaccharides, with a mannose content of over 75%, which is consistent with the pharmacopoeia using mannose content as the standard for measuring the effective ingredients of Dendrobium officinale. By comparison, in terms of molecular weight and monosaccharide composition, polysaccharides from Dendrobium officinale are closer to those from Dendrobium officinale.

This study used alloxan induced hyperglycemic mice as a model and found that polysaccharides from Dendrobium officinale, Dendrobium officinale, and Dendrobium nobile all had hypoglycemic activity. The hypoglycemic effect after 2 weeks of administration was consistent with the reported effect of 12 days of administration of Dendrobium officinale, Dendrobium huoshanense, Dendrobium nobile, etc., but significantly lower than the positive drug control. However, after 4 weeks of administration, the hypoglycemic effect of polysaccharides from Dendrobium nobile was significantly better than that of polysaccharides from Dendrobium officinale and Dendrobium nobile, and the effect was not significantly different from the positive drug control after 4 weeks of administration. The sentence is:.

This article compares the polysaccharides of Dendrobium officinale with those of Dendrobium officinale and Dendrobium nobile, and finds that the yield of polysaccharides from Dendrobium officinale is significantly higher than the latter two. The molecular weight of polysaccharides is relatively low, but the monosaccharide composition is consistent with that of Dendrobium officinale. In addition to having a higher biomass, the hypoglycemic activity of polysaccharides from Dendrobium officinale is significantly better than that of Dendrobium officinale and Dendrobium nobile after 4 weeks of administration, making it a potential substitute for Dendrobium officinale polysaccharides. In addition, the stem of Dendrobium officinale is thick and long, making it an excellent parent and providing breeding resources for the development of hypoglycemic Dendrobium polysaccharide resources.