Suppression of cyclooxygenase-2 and inducible nitric oxide synthase expression by epimuqubilin A via IKK/IκB/NF-κB pathways in lipopolysaccharide-stimulated RAW 264.7 cells

► A structurally unique norsesterterpene peroxide, isolated from marine sponge Latrunculia sp., epimuqubilin A, inhibits nitric oxide production with LPS-stimulated RAW 264.7 cells. ► Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are suppressed. ► Mitogen-activated protein kinases (MAPKs) are not affected. ► NF-κB p65 nuclear translocation and DNA binding are inhibited. ► Epimuqubilin A functions by the unique mechanism of inhibiting the phosphorylation of inhibitor κB (IκB) kinase (IKKβ).