Current Advances in the Biological Activity of Polysaccharides in Dendrobium with Intriguing Therapeutic Potential

The polysaccharides in many plants are attracting worldwide attention because of their biological activities and medical properties, such as anti-viral, anti-oxidative, antichronic inflammation, anti-hypertensive, immunomodulation, and neuron-protective effects, as well as anti-tumor activity. Denodrobium species, a genus of the family orchidaceae, have been used as herbal medicines for hundreds of years in China due to their pharmacological effects. These effects include nourishing the Yin, supplementing the stomach, increasing body fluids, and clearing heat. Recently, numerous researchers have investigated possible active compounds in Denodrobium species, such as lectins, phenanthrenes, alkaloids, trigonopol A, and polysaccharides. Unlike those of other plants, the biological effects of polysaccharides in Dendrobium are a novel research field. In this review, we focus on these novel findings to give readers an overall picture of the intriguing therapeutic potential of polysaccharides in Dendrobium, especially those of the four commonly-used Denodrobium species: D. huoshanense, D. offininale, D. nobile, and D. chrysotoxum.