Isoliquiritigenin isolated from Glycyrrhiza uralensis protects neuronal cells against glutamate-induced mitochondrial dysfunction

Glutamate-mediated excitotoxicity, which is associated with reactive oxygen species (ROS), is hypothesized to be a major contributor to pathological cell death in the mammalian central nervous system, and to be involved in many acute and chronic brain diseases.Here, we showed that isoliquiritigenin (ISL) isolated from Glycyrrhiza uralensis (Gu), one of the most frequently prescribed oriental herbal medicines, protected HT22 hippocampal neuronal cells from glutamate-induced oxidative stress. In addition, we clarified the molecular mechanisms by which it protects against glutamate-induced neuronal cell death. ISL reversed glutamate-induced ROS production and mitochondrial depolarization, as well as glutamate-induced changes in expression of the apoptotic regulators Bcl-2 and Bax. Pretreatment of HT22 cells with ISL suppresses the release of apoptosis-inducing factor from mitochondria into the cytosol. Taken together, our results suggest that ISL may protect against mitochondrial dysfunction by limiting glutamate-induced oxidative stress.In conclusion, our results demonstrated that ISL isolated from Gu has protective effects against glutamate-induced mitochondrial damage and hippocampal neuronal cell death. We expect ISL to be useful in the development of drugs to prevent or treat neurodegenerative diseases.

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► Isoliquritigenin reduced glutamate-induced neuronal cell death in HT22 cells.
► Isoliquritigenin inhibited glutamate-induced mitochondrial depolarization.
► Glutamate-induced changes in mitochondrial Bcl-2 and Bax levels were reversed by isoliquritigenin.
► Isoliquritigenin prevents the release of AIF from mitochondria.
► Isoliquritigenin protects neuronal cells against glutamate-induced mitochondrial dysfunction.