Rotatiridoid, a rare iridoid from Phlomoides rotata (Benth. ex Hook.f.) Mathiesen and its anti-inflammatory activity

A rare iridoid featuring an unusual 3-O-8 bridged ether bond, named rotatiridoid (1), was obtained from Phlomoides rotata (Benth. ex Hook.f.) Mathiesen, along with five known analogues. Its structure was established by means of HRESIMS, 1D and 2D NMR experiments, and ECD calculations. When evaluated in LPS-stimulated RAW 264.7 macrophages, compound 1 displayed anti-inflammatory activity, suppressing the production of pro-inflammatory mediators such as NO and ROS at 7.5 μM.