Activation of the transcription factor Nrf2 has been posited to be a promising therapeutic strategy in a number of inflammatory and oxidative stress diseases due to its regulation of detoxifying enzymes. In this work, we have developed a comprehensive structure-activity relationship around a known, naphthalene-based non-electrophilic activator of Nrf2, and we report highly potent non-electrophilic activators of Nrf2. Computational docking analysis of a subset of the compound series demonstrates the importance of water molecule displacement for affinity, and the X-ray structure of di-amide 12e supports the computational analysis. One of the best compounds, acid 16b, has an IC50 of 61 nM in a fluorescence anisotropy assay and a Kd of 120 nM in a surface plasmon resonance assay. Additionally, we demonstrate that the ethyl ester of 16b is an efficacious inducer of Nrf2 target genes, exhibiting ex vivo efficacy similar to the well-known electrophilic activator, sulforaphane.

Nuclear factor kappa B (NF-κB) is a key signaling molecule in the elaboration of the inflammatory response. Data indicate that curcumin, a natural ingredient of the curry spice turmeric, acts as a NF-κB inhibitor and exhibits both anti-inflammatory and anti-cancer properties. Curcumin analogues with enhanced activity on the NF-κB and other inflammatory signaling pathways have been developed including the synthetic monoketone compound termed 3,5-Bis(2-fluorobenzylidene)-4-piperidone (EF24). 3,5-Bis(2-pyridinylmethylidene)-4-piperidone (EF31) is a structurally-related curcumin analogue whose potency for NF-κB inhibition has yet to be determined. To examine the activity of EF31 compared to EF24 and curcumin, mouse RAW264.7 macrophages were treated with EF31, EF24, curcumin (1–100µM) or vehicle (DMSO 1%) for 1 hour. NF-κB pathway activity was assessed following treatment with lipopolysaccharide (LPS) (1µg/mL). EF31 (IC50 ~5µM) exhibited significantly more potent inhibition of LPS-induced NF-κB DNA binding compared to both EF24 (IC50~35µM) and curcumin (IC50 >50µM). In addition, EF31 exhibited significantly greater inhibition of NF-κB nuclear translocation as well as the induction of downstream inflammatory mediators including pro-inflammatory cytokine mRNA and protein (tumor necrosis factor-α, interleukin-1β, and interleukin-6). Regarding the mechanism of these effects on NF-κB activity, EF31 (IC50~1.92µM) exhibited significantly greater inhibition of IκB kinase β compared to EF24 (IC50~131µM). Finally, EF31 demonstrated potent toxicity in NF-κB-dependent cancer cell lines while having minimal and reversible toxicity in RAW264.7 macrophages. These data indicate that EF31 is a more potent inhibitor of NF-κB activity than either EF24 or curcumin while exhibiting both anti-inflammatory and anticancer activities. Thus, EF31 represents a promising curcumin analogue for further therapeutic development.

Because of their central importance in gene regulation and mediating the actions of many hormones, the nuclear receptors (NRs) have long been recognized as very important biological and pharmaceutical targets. Of all the surfaces available on a given NR, the singular site for regulation of receptor activity has almost invariably been the ligand-binding pocket of the receptor, the site where agonists, antagonists, and selective NR modulators interact. With our increasing understanding of the multiple molecular components involved in NR action, researchers have recently begun to look to additional interaction sites on NRs for regulating their activities by novel mechanisms. The alternate NR-associated interaction sites that have been targeted include the coactivator-binding groove and allosteric sites in the ligand-binding domain, the zinc fingers of the DNA-binding domain, and the NR response element in DNA. The studies thus far have been performed with the estrogen receptors, the androgen receptor (AR), the thyroid hormone receptors, and the pregnane X receptor. Phenotypic and conformation-based screens have also identified small molecule modulators that are believed to function through the NRs but have, as yet, unknown sites and mechanisms of action. The rewards from investigation of these NR alternate-site modulators should be the discovery of new therapeutic approaches and novel agents for regulating the activities of these important NR proteins.

“Stapled” peptides are typically designed to replace two non-interacting residues with a constraining, olefinic staple. To mimic interacting leucine and isoleucine residues, we have created new amino acids that incorporate a methyl in the γ-position of the stapling amino acid S5. We have incorporated them into a sequence derived from steroid receptor coactivator 2, which interacts with estrogen receptor α. The best peptide (IC50 = 89 nM) replaces isoleucine 689 with an S-γ-methyl stapled amino acid, and has significantly higher affinity than unsubstituted peptides (390 and 760 nM). Through x-ray crystallography and molecular dynamics studies, we show that the conformation taken up by the S-γ-methyl peptide minimizes syn-pentane interactions between α- and γ-methyl groups.

Therapeutic block of estrogen action is typically achieved with conventional antagonists (CAs), compounds that displace estradiol from the estrogen receptor (ER) and induce formation of an ER conformation that cannot bind to coactivator proteins, such as the steroid receptor coactivators (SRCs). As an alternative mode for blocking estrogen action, the authors seek small molecules that act as coactivator binding inhibitors (CBIs)-that is, they compete directly with SRC3 for interaction with estradiol-bound ER. CBIs would be interesting mechanistic probes of estrogen action and might also provide an alternative, more durable endocrine therapy for hormone-responsive breast cancer, where cellular adaptations lead to resistance to CAs. The authors have designed and optimized a set of time-resolved fluorescence resonance energy transfer (TR-FRET) assays to monitor the interaction of ER with SRC3 and ligands, and they have used them in high-throughput screens to discover small-molecule CBIs that are able to disrupt this interaction. These assays also distinguish CBIs from CAs. These robust and sensitive "mix-and-measure" assays use low concentrations of ER labeled with a europium chelate as FRET donor and a Cy5-labeled SRC as acceptor. This multiplexed protocol produces excellent signal-to-noise ratios (>100) and Z′ val-