Sesquiterpenes from the rhizome of Curcuma longa with inhibitory activity on superoxide generation and elastase release by neutrophils

Six new sesquiterpenes, curculonone A (1), curculonone B (2), curculonone C (3), curculonone D (4), 6α-hydroxycurcumanolide A (5), and 1,10-dehydro-10-deoxy-9-oxozedoarondiol (6), have been isolated from the rhizome of Curcuma longa, together with 19 known compounds. The structures of these new compounds were determined through spectroscopic and MS analyses. Compounds 1, 2, 5, 12, 15, 16, and 23 exhibited inhibition (IC50 ⩽ 18.22 μM) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (fMLP/CB). Compounds 5, 12–16, and 23 inhibited fMLP/CB-induced elastase release with IC50 values ⩽ 14.28 μM.