Modified secoiridoid from Acicarpha tribuloides and inhibition of nitric oxide production in LPS-activated macrophages

The search for nitric oxide inhibitors from Acicarpha tribuloides Juss. resulted in the isolation of an uncommon non-glycosylated secoiridoid, tribulolide (1), as well as two natural chromones together with two known secoiridoid glycosides. The secoiridoids showed inhibition of NO production in lipopolysaccharide-activated macrophages with activity comparable to aminoguanidine, a classic inhibitor.