Activation of NFκB is inhibited by curcumin and related enones Original Research Article

The transcription factor NFkappaB (NFκB) is up-regulated in many cancer cells where it contributes to development of the pro-survival, anti-apoptotic state. The natural product curcumin is a known inhibitor of activation of NFκB. Enone analogues of curcumin were compared with curcumin for their abilities to inhibit the TNFα-induced activation of NFκB, using the Panomics’ NFκB Reporter Stable Cell Line. The enones tested included curcumin analogues that retained the 7-carbon spacer between the aromatic rings, analogues with a 5-carbon spacer, and analogues with a 3-carbon spacer. Inhibitors of NFκB activation were identified in all three series, a number of which were more active than curcumin. Enone analogues in the series with the 5-carbon spacer were especially active, including members that contained heterocyclic rings. 1,5-Bis(3-pyridyl)-1,4-pentadien-3-one was the most active analogue, IC50 = 3.4 ± 0.2 μM. The most active analogues retain the enone functionality, although some analogues devoid of the enone functionality exhibited activity. The activity of the analogues as inhibitors of the activation of NFκB did not correlate with their anti-oxidant activity. The data suggest that the abilities of curcumin and analogues to prevent the stress-induced activation of NFκB result from the inhibition of specific targets rather than from activity as anti-oxidants.