The activation of the NF-κB transcription factor is a major adaptive response induced upon treatment with EGFR kinase inhibitors, leading to the emergence of resistance in nonsmall cell lung cancer and other tumor types. To suppress this survival mechanism, we developed new thiourea quinazoline derivatives that are dual inhibitors of both EGFR kinase and the NF-κB activity. Optimization of the hit compound, identified in a NF-κB reporter gene assay, led to compound 9b, exhibiting a cellular IC₅₀ for NF-κB inhibition of 0.3 μM while retaining a potent EGFR kinase inhibition (IC₅₀ = 60 nM). The dual inhibitors showed a higher potency than gefitinib to inhibit cell growth of EGFR-overexpressing tumor cell lines in vitro and in a xenograft model in vivo, while no signs of toxicity were observed. An investigation of the molecular mechanism of NF-κB suppression revealed that the dual inhibitors depleted the transcriptional coactivator CREB-binding protein from the NF-κB complex in the nucleus.

The first total synthesis of cystobactamid 507, a member of a class of new natural products with strong inhibitory activity towards bacterial topoisomerases, is reported. Synthetic key challenges are the central tetrasubstitued arene and the low chemical reactivity of anilines and ortho-phenolic and isopropoxy-substituted benzoic acids. Biological evaluations demonstrate that cystobactamid 507 inhibits several Gram-positive pathogens but at significantly lower concentrations than described for the larger members of this natural product family.