Cordatols A-D, four new anti-inflammatory bis-monoterpenoids from Illigera cordata.

Cordatols A-D (1-4), four new limonene-derived bis-monoterpenoids plausibly biosynthesized via hetero-Diels-Alder cyclization and sequential hydrolyses of their monoterpene precursors, were isolated from the aerial parts of Illigera cordata. The structures, including absolute configuration, were established by spectroscopic analysis and further confirmed by a two-steps bioinspired chemical transformation. Moreover, compounds 1-4 exhibited moderate in vitro anti-inflammatory activity with IC50 values ranging from 17.5 to 24.6 µM. This study may provide a novel structural template for potential anti-inflammatory agent discovery.