Radical-mediated C7 cholesterol oxidation during erastin-induced ferroptosis
*Correspondence to:
Yoshiro Saito, Laboratory of Molecular Biology and Metabolism, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
E-mail: Yoshiro.saito.a8@tohoku.ac.jp
EXO. 2026;1:202629. 10.70401/EXO.2026.0022
Received: August 17, 2026Accepted: October 28, 2026Published: October 28, 2026
This manuscript is made available in its unedited form to allow early access to the
reported findings. Further editing will be completed before final publication. As
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Abstract
Aims: Ferroptosis is driven by iron-dependent lipid peroxidation, but whether cholesterol undergoes radical-mediated oxidation during this process remains incompletely understood. We examined the temporal relationship between lipid peroxidation, cell death, and C7 cholesterol oxidation during erastin-induced ferroptosis.
Methods: Human SH-SY5Y cells were treated with erastin. Cell viability, lipid hydroperoxides, and lipid radicals were assessed using Alamar Blue, Liperfluo, and LipiRADICAL, respectively. Total 7α-hydroxycholesterol (t7α-OHCh), total 7β-hydroxycholesterol (t7β-OHCh), and 7-ketocholesterol (7-ketoCh) were quantified by GC–MS after triphenylphosphine reduction and saponification.
Results: Erastin-induced cell death was suppressed by deferoxamine, ferrostatin-1, and α-tocopherol. Liperfluo fluorescence increased before detectable LipiRADICAL fluorescence and loss of cell viability. t7α-OHCh increased during the early phase, whereas t7β-OHCh increased later; no statistically significant change in 7-ketoCh was detected. Because t7α-OHCh and t7β-OHCh represent composite pools of pre-existing free and esterified hydroxycholesterols and hydroperoxide-derived products, the early t7α-OHCh signal cannot distinguish enzymatic hydroxylation from a 7α-hydroperoxycholesterol (7α-OOHCh)-derived product. The increase in t7β-OHCh together with the overall C7 stereochemical profile is consistent with radical-mediated C7 cholesterol oxidation.
Conclusion: These findings support radical-mediated C7 cholesterol oxidation as an early component of erastin-induced ferroptotic lipid damage. The biological activity and extracellular transfer of these products remain to be established.
Keywords
Ferroptosis, cholesterol oxidation, lipid hydroperoxide, 7-hydroxycholesterol, oxysterol
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Akiba Y, Arisawa K, Kaneko T, Ishida K, Sato E, Toyama T, et al. Radical-mediated C7 cholesterol oxidation during erastin-induced ferroptosis. EXO. 2026;1:202629. https://doi.org/10.70401/EXO.2026.0022
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Akiba Y, Arisawa K, Kaneko T, Ishida K, Sato E, Toyama T, et al. Radical-mediated C7 cholesterol oxidation during erastin-induced ferroptosis. EXO. 2026;1:202629. https://doi.org/10.70401/EXO.2026.0022
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