Effects of (+)-eudesmin from the stem bark of magnolia kobus DC. var. borealis Sarg. on neurite outgrowth in PC12 cells

(+)-Eudesmin [4,8-bis(3,4-dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane] was isolated from the stem bark of Magnolia kobus DC. var. borealis Sarg. and found to have neuritogenic activity. 50 microM (+)-eudesmin induced neurite outgrowth and enhanced nerve growth factor (NGF)-mediated neurite outgrowth from PC12 cells. At this concentration, (+)-eudesmin also enhanced NGF-induced neurite-bearing activity and this activity was partially blocked by various protein kinase inhibitors. These included PD98059, a mitogen-activated protein kinase (MAPK) kinase inhibitor. GF109203X, a protein kinase C (PKC) inhibitor and H89, a protein kinase A (PKA) inhibitor. These results suggest that (+)-eudesmin can induce neurite outgrowth from PC12 cells by stimulating up-stream MAPK, PKC and PKA pathways.