Minor secoiridoid aglycones from the low-polarity part of the traditional Chinese herb: Swertia mileensis

Eleven new secoiridoid aglycones involving unusual C9-skeleton:swerimilegenins A-F(1-6);bis-C9-skeleton:swerimilegenin G(7);and C_(10)-skeleton:swerimilegenins H−K(8−11),as well as six known ones,were isolated from the low-polarity part of the traditional Chinese herb medicine Swertia mileensis.Their structures were determined by extensive spectroscopic data and X-ray diffraction.Biogenetically,swerimilegenin A(1)belonged to 10-nor-secoiridoid,and swerimilegenins B-F(2-6)were 1-nor-secoiridoids.Erythrocentaurin(12)and gentiogenal(15)showed moderate anti-HBV activity on HepG 2.2.15 cell line in vitro.