Ent- kaurane diterpenoids from Isodon japonica var. glaucocalyx with PCSK9 inhibitory activities

Three new (glaucocalyxin L-N, 1-3) and six known ent-kauranoids (4-9) were isolated from the aerial part of Isodon japonica var. glaucocalyx. Compounds 1 and 2 are ent-kaurane-type diterpenoids with an adenine group. The structures of the isolated compounds were established using NMR and MS measurements and the absolute configuration of compound 3 was determined using experimental and calculated electronic circular dichroism spectra. Compounds 6 and 8 showed relatively remarkable inhibitory activities on proprotein convertase subtilisin/kexin 9 (PCSK9) expression at 20 & mu;M.

Automated summary

Three new ent-kauranoids with an adenine group and six known ent-kauranoids were isolated from Isodon japonica var. glaucocalyx. The structures of the compounds were determined using NMR and MS measurements, and the absolute configuration of one compound was determined using experimental and calculated electronic circular dichroism spectra. Compounds 6 and 8 exhibited significant inhibitory activities on PCSK9 expression at 20 μM.