Elliptisides A-D, four new guaiane-type sesquiterpenoid dimers from Xylopia elliptica Maingay ex Hook.f. & Thomson

Four new guaiane dimers, elliptisides A-D, were isolated and characterized from the twigs of Xylopia elliptica Maingay ex Hook.f. & Thomson. Their structures were elucidated through comprehensive spectroscopic analysis and single-crystal X-ray diffraction. Elliptiside C possesses a novel connectivity pattern through two direct CC bonds (C-2 to C-3', C-3 to C-1', forming a previously unreported carbon skeleton. Biological evaluation demonstrated that elliptiside C moderately inhibits nitric oxide (NO) production in LPS-stimulated RAW264.7 macrophages, with an IC₅₀ value of 19.8 μM.