Dimeric ent-kauranoids isolated from Isodon japonica var. Glaucocalyx and their anti-inflammatory activities.

The phytochemical investigation of the aerial parts of Isodon japonica var. glaucocalyx afforded four undescribed (glaucocalyxin O-R, 1 – 4) and six known ent -kauranoids (5 – 10). Their structures were established using NMR and MS measurements. Compounds 1 and 2 are dimeric ent- kaurane-type diterpenoids. Moreover, the plausible biogenetic pathways for compounds 1 and 2 were proposed as Michael addition between two monomers. Eight compounds were assayed for their anti-inflammatory activity by evaluating NO production in LPS-induced RAW 267.4 cells, and compounds 7 , 8 and 9 exhibited relatively remarkable anti-inflammatory activities at 10 μM. [Display omitted] • Four undescribed diterpenoids were isolated from Isodon japonica var. glaucocalyx. • Compounds 1 and 2 are dimeric ent- kaurane-type diterpenoids. • Compounds 7, 8 and 9 exhibitedremarkable anti-inflammatory activities at 10 μM. [ABSTRACT FROM AUTHOR]