Identification of 4,5,6,7-Tetrabromo-1H-benzotriazole (TBB) as a Small Molecule MESH1 Inhibitor that Suppresses Ferroptosis

Mestre, A. A.; Oh, Y.; Wu, J.; Dunn, D.; Setayeshpour, Y.; Chen, S.-Y.; Lin, C.-C.; Cochrane, C. S.; Jeong, P.; Nam, G.; Markey, C.; Reker, D.; Floyd, S. R.; Hong, J.; Zhou, P.; Chi, J.-T. A.

doi:10.64898/2026.02.19.706832

bioRxiv · 10.64898/2026.02.19.706832

Identification of 4,5,6,7-Tetrabromo-1H-benzotriazole (TBB) as a Small Molecule MESH1 Inhibitor that Suppresses Ferroptosis

Mestre, A. A.·Oh, Y.·Wu, J.·Dunn, D.·Setayeshpour, Y.·Chen, S.-Y.·Lin, C.-C.·Cochrane, C. S.·Jeong, P.·Nam, G.·Markey, C.·Reker, D.·Floyd, S. R.·Hong, J.·Zhou, P.·Chi, J.-T. A.

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Abstract

Ferroptosis is a regulated form of cell death driven by iron-dependent lipid peroxidation and contributes to diverse pathologies including ischemia-reperfusion injury and neurodegenerative disorders. Current ferroptosis inhibitors largely function as nonspecific radical-trapping antioxidants, limiting their clinical utility. We previously identified MESH1 as a key regulator of ferroptosis through its NADPH phosphatase activity. Here, we identify 4,5,6,7-tetrabromo-1H-benzotriazole (TBB) as a small molecule inhibitor of MESH1 with an IC50 value of 4.7 {+/-} 0.3 {micro}M. X-ray crystallography revealed the molecular determinants of TBB recognition which are corroborated through structure-activity relationships of TBB analogs. TBB protected multiple cell lines against ferroptosis in vitro, and this effect was mitigated by MESH1 knockdown, consistent with on-target activity. Furthermore, TBB reduced neuronal death in an ex vivo brain slice model of Alzheimers disease. Collectively, these findings establish TBB as a bona fide small-molecule MESH1 inhibitor that suppresses ferroptosis and establishes MESH1 as a promising therapeutic target. Graphical AbstractDepicting mechanism of TBB suppressing ferroptosis through the inhibition of MESH1. Figure Created with Biorender.com O_FIG O_LINKSMALLFIG WIDTH=131 HEIGHT=200 SRC="FIGDIR/small/706832v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1fd60e9org.highwire.dtl.DTLVardef@1e56518org.highwire.dtl.DTLVardef@15010c2org.highwire.dtl.DTLVardef@17c313a_HPS_FORMAT_FIGEXP M_FIG C_FIG

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Mestre, A. A., Oh, Y., Wu, J., Dunn, D., Setayeshpour, Y., Chen, S.-Y., Lin, C.-C., Cochrane, C. S., Jeong, P., Nam, G., Markey, C., Reker, D., Floyd, S. R., Hong, J., Zhou, P., Chi, J.-T. A.. 2026-02-20. Identification of 4,5,6,7-Tetrabromo-1H-benzotriazole (TBB) as a Small Molecule MESH1 Inhibitor that Suppresses Ferroptosis. https://doi.org/10.64898/2026.02.19.706832

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