Humulane-type and germacrane-type sesquiterpenoids from the fruits of Xanthium spinosum Linn

Eight undescribed humulane-type sesquiterpenoids (xanthspinol A-E, I, J and N), three undescribed germacrane-type sesquiterpenoids (xanthspinol F, G and O) and twelve known compounds were isolated from the fruits of Xanthium spinosum. The structures of the undescribed compounds were elucidated by analyses of spectroscopic data, electronic circular dichroism (ECD) calculations, dimolybdenum tetraacetate [Mo2(OAc)4]-induced circular dichroism (ICD) spectra, a CD exciton chirality method and the modified Mosher's method. Xanthspinol A and B featured a humulane skeleton containing a 2,5-dihydrofuran fragment. Putative biosynthetic pathways for the undescribed compounds are proposed. Xanthspinol N, 8-epi-isoxanthanol and deacetyl-4-epixanthanol showed moderate activity against Coxsackie virus B3 (CVB3) with IC50 values of 8.70, 3.70 and 3.70 μM, respectively. [Display omitted] •Eleven undescribed sesquiterpenoids were isolated from Xanthium spinosum Linn.•Xanthspinol A and B featured a humulane skeleton with a 2,5-dihydrofuran fragment.•Plausible biosynthesis pathways of undescribed sesquiterpenoids were proposed.