Elemene mitigates oxidative stress and neuronal apoptosis induced by cerebral ischemia-reperfusion injury through the regulation of glutathione metabolism

Ethnopharmacological relevance: Chinese materia medica (CMM) has a long history and extensive experience in treating ischemic stroke. Wen Ezhu, the rhizome of Curcuma wenyujin Y.H. Chen et C. Ling, is renowned for promoting blood circulation, dispersing blood stasis, alleviating pain, and eliminating masses. Promoting blood circulation and removing blood stasis are essential principles in Traditional Chinese Medicine for treating stroke. Consequently, Wen Ezhu is frequently used in clinical practice as a key CMM for treating stroke. The Elemene active fraction (ELE), a sesquiterpene compound extracted from Wen Ezhu, primarily consists of β-Elemene. It also contains β-Caryophyllene, γ-Elemene, and δ-Elemene isomers. ELE has shown potential pharmacological effects in various diseases, including ischemic stroke. However, its precise mechanism of action in treating stroke remains to be confirmed.

Aim of the study: To explore the therapeutic potential of ELE in acute ischemic stroke and elucidate its underlying mechanisms.

Materials and methods: A rat model of middle cerebral artery occlusion reperfusion (MCAO/R) was used to evaluate ELE's effects. Therapeutic efficacy was assessed through mNSS scoring, magnetic resonance imaging (MRI), tetrazolium chloride (TTC) staining, Hematoxylin and eosin (H&E), and Nissl staining. Non-targeted metabolomics identified key pathways, confirmed using biochemical analysis, immunohistochemistry, and Western blotting. ROS levels and apoptosis-related proteins were also evaluated.

Results: Our findings show that ELE administration significantly reduced the cerebral infarct area and lowered modified neurological severity scores (mNSS) in animals, indicating a strong neuroprotective effect. Metabolomics results highlight the glutathione (GSH) metabolic pathway as a key mechanism through which ELE exerts its therapeutic effects. Specifically, ELE upregulates glutathione reductase (GR) protein expression and downregulates glutathione peroxidase (GPX) expression. The regulatory process of ELE decreases oxidized glutathione (GSSG) levels and increases GSH levels, effectively reducing oxidative stress damage (lower reactive oxygen species levels) during CI/RI. This results in the downregulation of the pro-apoptotic protein Bax and the upregulation of the pro-survival protein Bcl-2, thus reducing neuronal apoptosis.

Conclusions: ELE protects neurons in MCAO/R rats through the GSH metabolism pathway, balancing GSH and GSSG levels to mitigate oxidative stress and enhance neuroprotection in cerebral ischemia/reperfusion injury.