Non-peptidic immunoproteasome ß5i-selective inhibitor as potential treatment for idiopathic pulmonary fibrosis: Virtual screening, hit evolution and lead identification.

The immunoproteasome has emerged as a potential therapeutic target for idiopathic pulmonary fibrosis (IPF). We report herein our efforts to discover novel non-peptidic immunoproteasome inhibitors as potential treatment for IPF. A structure-based virtual screening was initially performed and the hit compound VS-7 with an IC50 of 9.437 µM against ß5i was identified. Hit evolution based on the interaction mode of VS-7 proceeded, and a potent ß5i inhibitor 54 (IC50 = 8.463 nM) with favorable subunit-selective profiles was obtained. Compound 54 also imposed significant effects on the release of TNF-α and IL-6, the transcriptional activity of NF-κB, as well as TGF-ß1 induced fibroblast proliferation, activation and collagen synthesis. Notably, when administered at 30 mg/kg in a bleomycin-induced IPF mouse model, compound 54 showed anti-fibrotic effects comparable to the clinical drug nintedanib. The results suggest that selective inhibition of immunoproteasome could be an effective approach to treat IPF.

Discovery of novel 1,2,4-triazole derivatives as xanthine oxidoreductase inhibitors with hypouricemic effects.

Xanthine oxidoreductase (XOR) is a clinically validated target for the treatment of hyperuricemia and gout. A series of novel 1,2,4-triazoles were identified as potent XO inhibitors via a fused-pharmacophore strategy based on the interaction modes of febuxostat and topiroxostat. Among them, compound 7i showed an IC50 value of 0.20 nM against XOR, which was superior to febuxostat and topiroxostat. Furthermore, 7i exhibited significant hypouricemic and serum XOR inhibitory effects in potassium oxonate induced hyperuricemia mouse models. A single-dose toxicity assessment of 7i showed no noticeable toxicity at the dose of 50 mg/kg. These results demonstrated that 7i could be a promising lead compound for the treatment of hyperuricemia and gout.

Identification of N, C-capped di- and tripeptides as selective immunoproteasome inhibitors.

A series of N, C-capped di- and tripeptides were designed as selective immunoproteasome inhibitors based on the known inhibitor 4-CA. Forty-eight new compounds were synthesized and evaluated, and the structure-activity relationship (SAR) of this compound class as ß5i selective inhibitors were explored. Most of these compounds showed significant inhibition against the ß5i subunit of the immunoproteasome and the most potent ß5i inhibitor (15) showed an IC50 of 0.94 nM. A selective ß5i inhibitor (54) with over 500-fold ß5i/ß5c selectivity was identified. Three of the inhibitors were found to selectively inhibit ß5i and ß5c, and showed no noticeable inhibition against the other four subunits. Six inhibitors with significant inhibitory activity against the HCT-116 cells were recognized, and the most active inhibitors, 14 and 50, showed IC50 values of 0.46 µM and 0.16 µM, respectively. Some selective ß5i inhibitors exhibited significant inhibitory effects on the release of the cytokines TNF-α and IL-6. The results not only afford effective chemical tools to elucidate the relationships between subunit selectivity and pharmacological profiles, but also offer useful clues for further optimization and development of selective immunoproteasome inhibitors.

Novel benzamido derivatives as PTP1B inhibitors with anti-hyperglycemic and lipid-lowering efficacy.

Based on a non-competitive and selective PTP1B inhibitor reported by us previously, thirty-nine benzamido derivatives were designed and synthesized as novel PTP1B inhibitors. Among them, twelve compounds exhibited IC50 values at micromolar level against human recombinant PTP1B, and most of them exhibited significant selectivity to PTP1B over TC-PTP and CD45. Further evaluation of the most potent compound 27 on high-fat diet (HFD)-induced insulin-resistant (IR) obese mice indicated that 27 could modulate glucose metabolism and ameliorate dyslipidemia simultaneously.

Carboxylic Acid-Promoted Single-Step Indole Construction from Simple Anilines and Ketones via Aerobic Cross-Dehydrogenative Coupling.

The cross-dehydrogenative coupling (CDC) reaction is an efficient strategy for indole synthesis. However, most CDC methods require special substrates, and the presence of inherent groups limits the versatility for further transformation. A carboxylic acid-promoted aerobic catalytic system is developed herein for a single-step synthesis of indoles from simple anilines and ketones. This versatile system is featured by the broad substrate scope and the use of ambient oxygen as an oxidant and is convenient and economical for both laboratory and industry applications. The existence of the labile hydrogen at C-3 and the highly transformable carbonyl at C-2 makes the indoles versatile building blocks for organic synthesis in different contexts. Computational studies based on the density functional theory (DFT) suggest that the rate-determining step is carboxylic acid-assisted condensation of the substrates, rather than the functionalization of aryl C-H. Accordingly, a pathway via imine intermediates is deemed to be the preferred mechanism. In contrast to the general deduction, the in situ formed imine, instead of its enamine isomer, is believed to be involved in the first ligand exchange and later carbopalladation of the α-Me, which shed new light on this indolization mechanism.