Electrophilic fatty acid nitroalkenes regulate Nrf2 and NF-κB signaling: A medicinal chemistry investigation of structure-function relationships

Fatty acid nitroalkene derivatives (NO2-FA) activate Nrf2-regulated antioxidant gene expression and inhibit NF-kappa B-dependent cytokine expression. To better define NO2-FA structure-function relationships, a series of 22 new chemical entities (NCEs) containing an electrophilic nitroalkene functional group were synthesized and screened for both Nrf2- and NF-kappa B activities using luciferase-based assays. The structural variables were acyl chain length (11 to 24 carbons) and position of the electrophilic nitroalkene group. In luciferase-based reporter assays, Nrf2 was maximally activated by omega-12 nitroalkene fatty acids while TNF alpha stimulated NF-kappa B-inhibition was maximal for omega-5 nitroalkenes. The top pathway-modulating NO2-FAs were a) evaluated for an ability to activate Nrf2-dependent signaling and inhibit NF-kappa B-dependent inflammatory responses of RAW264.7 cells and b) compared to electrophilic compounds in clinical development. These findings revealed that 8/9-nitro-eicos-8-enoic acid (NCE-10) was collectively the most effective NCE and that both the a and. acyl chain lengths influence nitroalkene activation of Nrf2 and inhibition of NF-kappa B signaling. This insight will guide development of more effective non-natural homologs of endogenously-detectable fatty acid nitroalkenes as anti-inflammatory and anti-fibrotic drug candidates.