Dendrobium denneanum belonging to the family Orchidaceae is a precious herbal plant and widely distributed in southwestern China and other parts of South Asia. The stems from the Dendrobium species have long been used for the treatment of fever, ophthalmic disorders, throat inflammation and chronic superficial gastritis.

However, D. nobile has become a rare and endangered Chinese traditional medicinal plant. As a result, D. denneanum has attracted much attention due to its wide distribution and pharmaceutical actions. Polysaccharides isolated from D. denneanum exhibited anti-tumor, antioxidant and immunomodulatory activities.

Previous investigations on the active low molecular weight compounds derived from D. denneanum resulted in the isolation of phenanthrenes, bibenzyls, flavonoids and phenolic acids. In the course of search for bioactive compounds from this plant, six new phenanthrene glycosides (1–6) were obtained by Chengdu Institute of Biology. Researchers from the institute studyed the isolation and characterization of the new compounds and their cytotoxic activities against SNU387 cell line derived from hepatocellular carcinoma patients with hepatitis B virus infections

In the study, five new phenanthrene glycosides, denneanosides A-E (1-5), and one new 9,10-dihydrophenanthrene glycoside, denneanoside F (6) were isolated from the stem of Dendrobium denneanum. The chemical structures of the new compounds were established on the basis of extensive spectroscopic data. The isolated compounds were evaluated for their in vitro cytotoxic activity against SNU387 hepatocellular carcinoma cell line. Compounds 1-3 showed moderate cytotoxic activities while compounds 4-6 showed weak activities. More results have been published in PHYTOCHEMISTRY LETTERS. 

This research got supports from the National Eleventh-Five Year Research Program of China and National New Drug Innovation Major Project of China.