Various diarylheptanoids including curcumin, bis (3,4-dihydroxy-cinnamoyl) methane, and yakuchinones A & B were screened and found to be potent inhibitors of 5-HETE production by intact human neutrophils, with respective IC50 values of 8.0, 4.4, 5.4, and 4.0 microM. These diarylheptanoids were found to be more potent than BW-755C, Phenidone, and AA-861. We have confirmed a previous report that several of these diarylheptanoids inhibit cyclooxygenase. Thus, curcuminoids and yakuchinones are more accurately characterized as dual inhibitors of arachidonic acid metabolism.