Kadcoccinoids A-K, triterpenoids from Kadsura coccinea with PCSK9 expression inhibitory activities

Two undescribed protostane-type triterpenoids (1–2), and nine undescribed lanostane-type triterpenoids (3–11), along with nine known compounds (12–20) were isolated from the stems of Kadsura coccinea. Their chemical structures were elucidated by extensive spectroscopic analyses, Mosher's method, X-ray crystallography, and electronic circular dichroism calculations. Kadcoccinoid A (1) possesses an undescribed 6/6/8-fused carbocyclic core containing a rare bicyclo [4.2.1] nonan-9-one system and proposed plausible biosynthetic pathway. Additionally, kadcoccinoid B (2) significantly decreased PCSK9 protein levels in the medium of HepG2 cells at 10 μM with an inhibition rate of 78.4 % and increased LDL uptake at 5 and 10 μM, while compounds 12–14 showed moderate PCSK9 inhibitory activities.