New eremophilane-type sesquiterpenes from Synotis solidaginea.

Eleven new highly oxygenated eremophilane-type sesquiterpenoids were isolated from the whole plant of Synotis solidaginea, including two pairs of C-8 S/R epimers. The structures of the new compounds were elucidated on the basis of detailed spectroscopic analysis and the absolute configurations of 1 and 9 were confirmed by single-crystal X-ray crystallography using Cu Kα radiation. All the isolates were tested for the inhibition of LPS-stimulated NO production in macrophage-like mouse monocytic leukemia RAW264.7 cells. Compound 1 exhibited weak inhibitory effects with an IC50 of 71.2 µM.

Hexachlorophene, a selective SHP2 inhibitor, suppresses proliferation and metastasis of KRAS-mutant NSCLC cells by inhibiting RAS/MEK/ERK and PI3K/AKT signaling pathways.

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations account for 35% of the genetic alterations in non-small cell lung cancer (NSCLC). The Src-homology region 2-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, is closely involved in RAS downstream pathways and development of many tumors by affecting cell proliferation, differentiation, and immunity. Targeting SHP2 with small molecules may be a promising avenue for the treatment of KRAS-mutant (mut) NSCLC. Herein, hexachlorophene (HCP) was identified as a SHP2 inhibitor with an IC50 value of 5.63 ± 0.75 µM through screening of the FDA-approved drug library. HCP specifically inhibited SHP2 rather than other phosphatases. Molecular docking showed that HCP displayed an orientation favorable for nucleophilic attack in the catalytic domain of SHP2. HCP suppressed viability of multiple KRAS-mut and KRAS-wild type cells and induced senescence and apoptosis in KRAS-mut cells. Moreover, HCP reversed epithelial-mesenchymal transition to suppress metastasis in KRAS-mut cells, and inhibited the RAS/MEK/ERK and PI3K/AKT signaling pathways by suppression of SHP2 phosphorylation and formation SHP2/Grb2/Gab1/SOS1 complex. In summary, HCP can act as a specific SHP2 inhibitor to inhibit KRAS-mut NSCLC cell proliferation and metastasis and induce senescence through suppression of the RAF/MEK/ERK and PI3K/AKT pathways. HCP warrants further investigation as a new compound skeleton for the development of selective SHP2 inhibitors for the treatment of NSCLC.

A small molecule inhibitor of caspase-1 inhibits NLRP3 inflammasome activation and pyroptosis to alleviate gouty inflammation.

Caspase-1 is an integral regulator of innate immunity, which plays a key role in inflammasome activation and the release of pro-inflammatory cytokines. The development of novel non-peptidic small molecule caspase-1 inhibitors is an important strategy for antagonizing excessively activated caspase-1 induced by inflammatory diseases, including gouty arthritis. In the present study, we identified 63 caspase-1 inhibitors, with different structures and potencies, from bioactive compound libraries. Among them, NSC697923 potently inhibited the enzymatic activity of caspase-1, with an IC50 value of 1.737 µM. This compound adopted a favorable conformation in the active pocket of caspase-1. Furthermore, NSC697923 potently decreased mature interleukin (IL)-1ß secretion in macrophages stimulated by lipopolysaccharide plus nigericin, ATP, and monosodium urate crystal. NSC697923 also inhibited NLRP3 protein expression by suppressing the NF-κB signaling pathway and the interaction between receptor interacting protein-2 (RIP2) and pro-caspase-1, thereby blocking the priming of the NLRP3 inflammasome. In addition, NSC697923 significantly inhibited caspase-1 mediated gasdermin D cleavage and pyroptosis in macrophages. In an animal model of gouty arthritis, NSC697923 effectively inhibited joint swelling, IL-1ß release, and NLRP3 inflammasome activation. Our results indicate that NSC697923 can effectively suppress NLRP3 inflammasome activation by inhibiting caspase-1, thus warranting further investigation as a potential therapeutic for treating NLRP3 inflammasome-related diseases.