Target Fishing Reveals a Novel Mechanism of 1,2,4-Oxadiazole Derivatives Targeting Rpn6, a Subunit of 26S Proteasome.

1,2,4-Oxadiazole derivatives, a class of Nrf2-ARE activators, exert an extensive therapeutic effect on inflammation, cancer, neurodegeneration, and microbial infection. Among these analogues, DDO-7263 is the most potent Nrf2 activator and used as the core structure for bioactive probes to explore the precise mechanism. In this work, we obtained compound 7, a mimic of DDO-7263, and biotin-labeled and fluorescein-based probes, which exhibited homologous biological activities to DDO-7263, including activating Nrf2 and its downstream target genes, anti-oxidative stress, and anti-inflammatory effects. Affinity chromatography and mass analysis techniques revealed Rpn6 as the potential target protein regulating the Nrf2 signaling pathway. In vitro affinity experiments further confirmed that DDO-7263 upregulated Nrf2 through binding to Rpn6 to block the assembly of 26S proteasome and the subsequent degradation of ubiquitinated Nrf2. These results indicated that Rpn6 is a promising candidate target to activate the Nrf2 pathway for protecting cells and tissues from oxidative, electrophilic, and exogenous microbial stimulation.

Advances in Cryochemistry: Mechanisms, Reactions and Applications.

It is counterintuitive that chemical reactions can be accelerated by freezing, but this amazing phenomenon was discovered as early as the 1960s. In frozen systems, the increase in reaction rate is caused by various mechanisms and the freeze concentration effect is the main reason for the observed acceleration. Some accelerated reactions have great application value in the chemistry synthesis and environmental fields; at the same time, certain reactions accelerated at low temperature during the storage of food, medicine, and biological products should cause concern. The study of reactions accelerated by freezing will overturn common sense and provide a new strategy for researchers in the chemistry field. In this review, we mainly introduce various mechanisms for accelerating reactions induced by freezing and summarize a variety of accelerated cryochemical reactions and their applications.

Development of Novel Tetrahydroquinoline Inhibitors of NLRP3 Inflammasome for Potential Treatment of DSS-Induced Mouse Colitis.

The NLRP3 inflammasome is a critical component of innate immunity, which defends internal and external threats. However, inappropriate activation of the NLRP3 inflammasome induces various human diseases. In this study, we discovered and synthesized a series of tetrahydroquinoline inhibitors of NLRP3 inflammasome. Among these analogues, compound 6 exhibited optimal NLRP3 inhibitory activity. In vitro studies indicated that compound 6 directly bound to the NACHT domain of NLRP3 but not to protein pyrin domain (PYD) or LRR domain, inhibited NLRP3 ATPase activity, and blocked ASC oligomerization, thereby inhibiting NLRP3 inflammasome assembly and activation. Compound 6 specifically inhibited the NLRP3 inflammasome activation, but had no effect on the activation of NLRC4 or AIM2 inflammasomes. Furthermore, in the dextran sulfate sodium (DSS)-induced colitis mouse model, compound 6 exhibited significant anti-inflammatory activity through inhibiting NLRP3 inflammasome in vivo. Therefore, our study provides a potent NLRP3 inflammasome inhibitor, which deserves further structural optimization as a novel therapeutic candidate for NLRP3-driven diseases.

Selective apoptosis-inducing activity of synthetic hydrocarbon-stapled SOS1 helix with d-amino acids in H358 cancer cells expressing KRASG12C.

Lung cancer is one of the most malignant tumors with the highest morbidity and mortality. Most of them are non-small cell lung cancer (NSCLC). KRASG12C gene mutation is an important driving factor for NSCLC. However, the development of high-affinity inhibitors targeting KRASG12C mutants remains a daunting challenge. Here, we report the design and development of a series of hydrocarbon-stapled peptides containing d-amino acids to mimic the alpha helix of SOS1. D-hydrocarbon-stapled peptides maintain good alpha helix structure and bind to KRASG12C with high affinity. Subsequent anti-proliferation experiments indicated that D-hydrocarbon-stapled peptide 5 inhibited the proliferation of NSCLC H358 cells carrying KRASG12C. However, it showed no significant anti-proliferative effect on KRASG12S-positive A549 cells, suggesting that peptide 5 selectively inhibits KRASG12C-driven tumor cells. D-hydrocarbon-stapled peptide 5 could also cause the cell cycle of H358 cells to arrest in the G2/M phase and induce apoptosis. No significant cell arrest and apoptosis were observed in A549 cells treated by peptide 5. In summary, the introduction of d-amino acids could improve the affinity and cell selectivity of hydrocarbon peptides. We hope that peptides containing D-form amino acids can provide strategies for further optimization of the KRASG12C/SOS1 inhibitor.