Novel highly oxygenated and B-ring-seco-ent-diterpene glucosides from the seeds of Prinsepia utilis

Abstract Two novel highly oxygenated and one rare B-ring cleave ent -kaurane diterpene glucosides, named prinsoside A ( 1 ), B ( 2 ) and C ( 3 ), respectively, were isolated from an ethanolic extract of the seeds of Prinsepia utilis . To our knowledge, prinsoside B ( 2 ) was the most highly oxygenated ent -kaurane diterpene glucoside discovered in nature. Their structures were elucidated by various spectroscopic methods including 1D, 2D NMR and HR-ESI-MS analyses, with the absolute configurations clarified by CD measurements on their corresponding diterpenoid aglycones obtained by enzymatic hydrolysis with β-glucosidase. Compounds 1 – 3 exhibited weak α-glucosidase inhibitory activities.