Small molecule deoxynyboquinone triggers alkylation and ubiquitination of Keap1 at Cys489 on Kelch domain for Nrf2 activation and inflammatory therapy.

Activation of nuclear factor erythroid 2-related factor 2 (Nrf2) by Kelch-like ECH-associated protein 1 (Keap1) alkylation plays a central role in anti-inflammatory therapy. However, activators of Nrf2 through alkylation of Keap1-Kelch domain have not been identified. Deoxynyboquinone (DNQ) is a natural small molecule discovered from marine actinomycetes. The current study was designed to investigate the anti-inflammatory effects and molecular mechanisms of DNQ via alkylation of Keap1. DNQ exhibited significant anti-inflammatory properties both in vitro and in vivo. The pharmacophore responsible for the anti-inflammatory properties of DNQ was determined to be the α, ß-unsaturated amides moieties by a chemical reaction between DNQ and N-acetylcysteine. DNQ exerted anti-inflammatory effects through activation of Nrf2/ARE pathway. Keap1 was demonstrated to be the direct target of DNQ and bound with DNQ through conjugate addition reaction involving alkylation. The specific alkylation site of DNQ on Keap1 for Nrf2 activation was elucidated with a synthesized probe in conjunction with liquid chromatography-tandem mass spectrometry. DNQ triggered the ubiquitination and subsequent degradation of Keap1 by alkylation of the cysteine residue 489 (Cys489) on Keap1-Kelch domain, ultimately enabling the activation of Nrf2. Our findings revealed that DNQ exhibited potent anti-inflammatory capacity through α, ß-unsaturated amides moieties active group which specifically activated Nrf2 signal pathway via alkylation/ubiquitination of Keap1-Kelch domain, suggesting the potential values of targeting Cys489 on Keap1-Kelch domain by DNQ-like small molecules in inflammatory therapies.

The "whole ingredients extract" of Astragali Radix improves the symptoms of dextran sulfate sodium-induced ulcerative colitis in mice through systemic immunomodulation.

BACKGROUND: Ulcerative colitis (UC) is a common inflammatory intestinal disease. Astragali Radix (AR) is one of the traditional Chinese medicines used in clinic for UC treatment. In our previous study, the whole ingredient extract (WIE) from AR have been proved to possess better immunomodulatory effects on immunosuppressed mice compared with the conventional water extraction (WAE). In the present study, we further evaluated the therapeutic effects of WIE against dextran sodium sulfate (DSS)-induced UC in mice through systemic immune regulation. METHODS: Gradient solvent extraction has been used to prepare the WIE of AR. The HPLC-MS analysis approach has been employed to analyze and compare the chemical differences between WAE and WIE. UC model was reproduced in 3% DSS-induced C57BL/6 mice for 6 days. Flow cytometric analysis for splenic lymphocyte subset. ELISA kits were used to determine the cytokines in the serum and colon tissues. The histopathological characteristics of colon were evaluated by hematoxylin-eosin staining and immunohistochemistry. RESULTS: The chemical compositions and the contents of main active ingredients were more abundant and higher in WIE than those in WAE. The WIE treatment altered a better action on reducing colitis disease activity index (DAI) and histological scores, as well as the recovered body weight and increased colon length in mice compared to the WAE group. Additionally, WIE showed better effects in recovering the levels of peripheral white blood cells in blood and cytokines (IL-2, IL-6 and MCP-1) in serum or colon tissues, improving the percentage of CD3+ and the ratio of CD4+/CD8+ in the spleen, and inhibiting the spleen enlargement in DSS-induced UC mice. CONCLUSIONS: WIE has a more complete chemical composition than WAE. Meanwhile, WIE possesses better therapeutic effects on UC through resuming dysfunctional immunity in mice.