Edible Marine Alga Gracilariopsis chorda Alleviates Hypoxia/Reoxygenation Induced Oxidative Stress in Cultured Hippocampal Neurons

Abstract

Age related neurological disorders are growing concern among the elderly persons. Natural products with synergistic properties have been increasing attention as potential candidates for the prevention or treatment of neurological disorders induced by oxidative stress. As an effort to explore the natural resources that may have neuroprotective activity, we collected some common marine algae and screened for their neuroprotective activity based on propidium iodide (PI) and lactate dehydrogenase (LDH) assays for the viability of rat primary hippocampal neurons against hypoxia/reoxygenation (H/R) induced cell death. Of the 24 seaweeds examined, the ethanol extract of Gracilariopsis chorda (GCE) provided maximum neuroprotection with the optimum concentration of 15 μg/mL, followed by Undaria pinnatifida. To elucidate the underlying mechanism of action, we measured reactive oxygen species (ROS) positive cells by fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCF) staining, pohospho-H2AX (early apoptotic marker) by immunocytochemistry, apoptotic cells by Annexin V/PI staining, DNA fragmentation by agarose gel electrophoresis, and mitochondrial membrane potential (MMP) by JC-1 labeling. The results showed that GCE extract treatment significantly inhibited the ROS production, the expression of phospho-H2AX, apoptosis, DNA fragmentation, and preserve MMP. Taken together, our findings suggest that GCE could exert strong neuroprotection against H/R-induced neuronal death through the prevention of reactive molecules and eventually suppression of apoptosis.