Brusatol

Brusatol (BRU), a major bioactive quassinoid isolated from Brucea javanica, has shown potential in the treatment of inflammatory diseases. As mitochondrial dysfunction has been implicated in chronic inflammatory disorders, modulation of mitochondrial homeostasis may offer a potential approach for the treatment of rheumatoid arthritis (RA) and atherosclerosis (AS).

To develop a novel BRU derivative through rational modification at the C11‑hydroxyl group and to compare the therapeutic effects of BRU and its derivative BRUD in experimental models of RA and AS, with particular focus on mitochondrial regulation and Drp1-associated signaling.

This study combined in vivo and in vitro experiments to evaluate the pharmacological effects of BRU and BRUD and investigate the underlying mechanisms.

The chemical constituents of BRU and BRUD were confirmed by HPLC and NMR spectroscopy (¹H and ¹³C). Their effects were evaluated in vivo using collagen-induced arthritis (CIA) rats and apolipoprotein E-deficient (ApoE^-/-) mice, and in vitro using RA fibroblast-like synoviocytes (RA-FLS), as well as IL-8-stimulated normal endothelial cells (ECs) and smooth muscle cells (SMCs). Cell viability, apoptosis, migration, invasion, adhesion, and tube formation assays were performed to assess cellular responses. Histological, biochemical, flow cytometric, confocal imaging, Western blot, molecular docking/molecular dynamics, surface plasmon resonance (SPR), and Drp1 overexpression rescue assays were performed to assess disease phenotypes, mitochondrial alterations, and Drp1-associated signaling.

In vivo studies demonstrated that both compounds ameliorated joint damage in CIA rats and reduced atherosclerotic lesion burden in ApoE^-/- mice. In vitro, BRUD more effectively inhibited pathogenic FLS activation than BRU, and restored normal EC and SMC function. Mechanistically, the stronger activity of BRUD was associated with attenuation of Drp1-related mitochondrial fission, accompanied by reduced mtROS levels and restoration of ΔΨm.

These findings suggest that BRUD exhibits improved activity compared with BRU in RA and AS models, with protective effects associated with modulation of mitochondrial dysfunction, supporting its further evaluation as a lead compound.

Deoxynivalenol (DON) is one of the most prevalent mycotoxins in food and animal feed and poses substantial risks to intestinal health. Although DON is known to impair epithelial barrier function, its molecular mechanisms remain incompletely defined. Nuclear factor erythroid 2-related factor 2 (Nrf2) has emerged as an important regulator in mycotoxin-induced barrier disruption. 4-Methylcatechol (4-MC), a microbial metabolite of dietary polyphenols, has been shown to activate Nrf2, but its ability to counteract DON toxicity has not been fully evaluated. This study investigated the protective effects of 4-MC against DON-induced intestinal barrier dysfunction in IPEC-J2 cells and weaned piglets, with emphasis on the Nrf2 pathway. Treatment with 4-MC induced a dose-dependent increase in the Nrf2 target gene NAD(P)H:quinone oxidoreductase 1 (NQO1) and enhanced claudin-4 expression at both mRNA and protein levels. Importantly, 4-MC reversed DON-mediated suppression of claudin-4 and prevented the loss of claudin-4 and ZO-1 from the cell membrane. Functionally, 4-MC restored transepithelial electrical resistance (TEER) and reduced DON-induced FITC-dextran permeability, indicating improved barrier integrity. These protective actions were abolished by brusatol, an Nrf2 inhibitor, confirming that Nrf2 activation is essential for the barrier-preserving effects of 4-MC. In the piglet model, DON exposure caused villus atrophy, fusion, and epithelial necrosis, whereas dietary 4-MC alleviated these histopathological lesions. Overall, the findings demonstrate that 4-MC significantly mitigates DON-induced intestinal epithelial damage through mechanisms largely dependent on Nrf2 activation, supporting its potential as a dietary strategy to protect intestinal health.