Sigesbeckia K and L, two new diterpenoids from Sigesbeckia glabrescens with anti-inflammatory activity

Abstract

A chemical investigation of Sigesbeckia glabrescens Makino identified four compounds. On the basis of spectroscopic data, they were determined to be ent-pimarane-type diterpenoids and their analogues, among which were two previously undescribed compounds, Sigesbeckia K (1) and Sigesbeckia L (2). The anti-inflammatory effects of these compounds were evaluated by testing their inhibition of LPS-induced NO production in BV2 microglial cells, which revealed potential inhibitory effects with IC50 value at 62.56 μM and compared with the positive control minocycline (IC50 32.84 μM).