Sesquiterpene glycosides from Dendrobium nobile and their chemotaxonomic significance

Phytochemical investigation of the stems of Dendrobium nobile Lindl., led to the isolation of six sesquiterpene glycosides, including dendronobiloside E (1), dendronobiloside C (2), dendronobiloside D (3), dendronobiloside A (4), dendromoniliside D (5), dendroside G (6). Their chemical structures were identified on the basis of HR-ESI-MS, NMR spectroscopic analyses and comparison with reported data. Among them, dendronobiloside E (1) was a new compound. The chemotaxonomic significance of these sesquiterpene glycosides was discussed herein.