Eight ent-Kaurane Diterpenoid Glycosides Named Diosmariosides A–H from the Leaves of Diospyros maritima and Their Cytotoxic Activity

Abstract

From the leaves of Diospyros maritima, collected from Okinawa Island, eight new glycosides based on ent-kaurane-type diterpenoids, entitled diosmariosides A–H, were isolated. The absolute structure of diosmarioside E (5) was determined by X-ray crystallographic analysis. The structure of diosmarioside H was elucidated to be a dimeric compound between diosmarioside A and a sugeroside through a ketal bond. An assay of cytotoxicity towards the lung adenocarcinoma (A549) cell line was performed. Among the compounds isolated, only diosmarioside D (4) and sugeroside 9 showed strong activity. The anti-microbial activity toward multi-drug resistant strains was also determined, but no activity was observed.

Graphical Abstract