NITRIC-OXIDE SCAVENGING BY CURCUMINOIDS

Because curcumin, a compound with anti-inflammatory and anticancer act ivity, inhibits induction of nitric oxide synthase in activated macrop hages and has been shown to be a potent scavenger of free radicals we have investigated whether it can scavenge nitric oxide directly. Curcu min reduced the amount of nitrite formed by the reaction between oxyge n and nitric oxide generated from sodium nitroprusside. Other related compounds, e.g. demethoxycurcumin, bisdemethoxycurcumin and diacetylcu rcumin were as active as curcumin, indicating that the methoxy and the phenolic groups are not essential for the scavenging activity. The re sults indicate curcumin to be a scavenger of nitric oxide. Because thi s compound is implicated in inflammation and cancer, the therapeutic p roperties of curcumin against these conditions might be at least partl y explained by its free-radical scavenging properties, including those toward nitric oxide.