Bioactive cembrane diterpenoids from the gum resin of Boswellia carterii

Eight new cembrane-type diterpenoids, boscartins AP-AW (1-8) were obtained from the gum resin of Boswellia carterii. Among which, six ones (2-7) were isomers, with one hydroxy group and two double bonds migrating along the carbocycle. The structures were elucidated by spectroscopic examination. All isolates were evaluated for anti-inflammatory activity and hepatoprotective activity by cell models of LPS-induced RAW 264.7 mouse peritoneal macrophages and APAP-induced HepG2 cells, respectively. As for anti-inflammatory activity assay, compound 1 exhibited potent activity against NO production (IC₅₀ of 13.1 μM), with the other ones exhibiting weak anti-inflammatory activity (IC₅₀ > 50 μM). As for hepatoprotective activity assay, compound 1 exhibited more significant activity (inhibition rate of 30.7%) than that of the positive control (bicyclol, inhibition rate of 27.2%), and compounds 4, and 6 showed nearly the same activities as the control (inhibition rates of 26.7% and 25.9%, respectively), with the other ones exhibiting weak hepatoprotective activity.

Keywords: Anti-inflammatory; Boswellia carterii; Cembrane; Hepatoprotective activity.