Subacute Toxicological Evaluation of 9‐Methylfascaplysin, a Marine‐Derived Neuroprotective Compound, via an Integrated Multiomics Approach

9-Methylfascaplysin (9-MF) is a novel marine-derived neuroprotective compound with potential for the development as a therapeutic agent for Alzheimer's disease and ischemic stroke. However, its systematic toxicological profile remains to be fully characterized. In this study, the subacute toxicity of 9-MF was evaluated in male and female Sprague-Dawley rats following 14 consecutive days of intravenous administration. 9-MF at 1-5 mg/kg did not induce significant alterations in body weight, food consumption, motor function, or anxiety-like behavior. Sex-dependent sensitivity to 9-MF-induced hepatotoxicity was observed. Furthermore, 9-MF induced mild hepatic inflammation, red pulp hemorrhage in the spleen, inflammatory cell infiltration, and alveolar septal thickening in the lung, as well as mild neuronal degeneration and structural loosening in the dentate gyrus region of the brain. Integrated transcriptomic, proteomic, and metabolomic analyses further revealed that 5 mg/kg 9-MF regulated 6-pyruvoyltetrahydropterin synthase-centered biopterin metabolism, arachidonate 15-lipoxygenase-centered linoleate metabolism, and the mTOR pathway in the brain, as well as SMPD4/phytosphingosine-centered sphingolipid metabolism, PLA2G2A-centered arachidonic acid metabolism, and GMPR-centered porphyrin metabolism in the blood, contributing to the observed abnormalities. These findings not only provided a toxicological basis for the further drug development of 9-MF but also served as an example of a toxicological study integrating traditional assessments with multiomics strategies.