Neurite outgrowth activity of cyathane diterpenes from Sarcodon cyrneus, cyrneines A and B

Two new cyathane diterpenes, cyrneines A (1) and B (2), were isolated from the mushroom Sarcodon cyrneus. The structures of the novel diterpenoids were determined by analysis of their spectroscopic data. Neither cyrneine A nor cyrneine B at 100 PM showed cytotoxicity as determined by LDH analysis. The stimulating activity on neurite outgrowth of cyrneines was evaluated. Rat pheochromocytoma cells (PC12), used as a model system of neuronal differentiation, were cultured with cyrneine A (100 mu M), cyrneine B (100 mu M) or NGF (100 ng/ml) for 24 h. Interestingly, cyrneines A and B significantly promoted neurite outgrowth in addition to NGF as a positive control.