6,7‐dihydroxy‐2,4‐dimethoxy phenanthrene isolated from Dioscorea batatas peel suppresses microglia‐associated neuroinflammation in vitro

Abstract

Inflammation occured in the neural tissue is a cause of neurodegenerative diseases. Our previous study showed that the ethanolic extract of Dioscorea batatas Decne peel promoted antioxidant mechanism in colonic epithelial cells and attenuated inflammatory response in activated macrophages. Recently, 6, 7‐dihydroxy 2, 4‐dimethoxy phenanthrene (DDP) has been identified as one of the bioactive compounds having antioxidative and anti‐inflammatory activities. The current study aimed at examining the neuroprotective potential of DDP by staving off neuroinflammation. Our data demonstrated that (1) DDP decreased glutamate‐induced murine hippocampal neuronal cell death; hlowever, there was no significant increase in ARE‐luciferase activity, (2) DDP decreased the expressions of nuclear NF‐κB and its downstream proteins in BV2 murine microglial cells and thereby lowered NO production and cytokine secretion, and (3) DDP increased the production of antioxidant enzyme, heme oxygenase 1(HO‐1) in BV2 murine microglial cell. These results indicate that DDP suppressed microglial activation which generally causes neuroinflammation. In consideration of our observations implying that DDP may not directly stimulate the antioxidant mechanism in neuronal cells for its in vitro neuroprotective effect, DDP would possibly enhance neuronal cell survival due to its anti‐neuroinflammatory capability in microglia. The interaction between neuronal cells and microglia cells in culture as well as under physiological conditions awaits further study.