Novel IKK inhibitors: β-carbolines

Inhibitors of IκB kinase (IKK) have long been sought as specific regulators of NF-κB. A screening effort of the endogenous IKK complex allowed us to identify 5-bromo-6-methoxy-β-carboline as a nonspecific IKK inhibitor. Optimization of this β-carboline natural product derivative resulted in a novel class of selective IKK inhibitors with IC50s in the nanomolar range. In addition, we show that one of these β-carboline analogues inhibits the phosphorylation of IκBα and subsequent activation of NF-κB in whole cells, as well as blocking TNF-α release in LPS-challenged mice.