Discovery of ent-kaurane diterpenoids, characteristic metabolites of Isodon species, from an endophytic fungal strain Geopyxis sp. XY93 inhabiting Isodon parvifolia.

Isogeopyxins A–C (1 – 3), three new diterpenoids with ent -kaurane, ent -pimarane, and ent -abietane scaffolds, respectively, along with six known ent -kauranoids, were isolated from the fermentation culture of Geopyxis sp. XY93 inhabiting the leaves of Isodon parvifolia. Their structures were elucidated by interpretation of spectroscopic data, and single crystal X-ray diffraction. It marks the first time that ent -kauranoids, characteristic metabolites of Isodon species, have been isolated from an associated endophytic fungus. [Display omitted] • Chemical investigation on endophytic Geopyxis sp. XY93 of Isodon parvifolia led to the discovery of 9 diterpenoids. • Characteristic metabolites of Isodon species were isolated from an associated endophytic fungus for the first time. • ent -Kauranoids from Geopyxis sp. XY93 exhibited good cytotoxic effects against liver cancer cells. [ABSTRACT FROM AUTHOR]