12alpha-hydroxy-N-demethyl-sauroxine (1), another new Lycopodium alkaloid from the Lycodane group, was isolated from Phlegmariurus saururus (Lam.) B. Ollg. (Lycopodiaceae). Elucidation of the chemical structure and relative stereochemistry were stated by spectroscopic data and chemical correlation. In addition, the inhibitory activity on acetylcholinesterase for 1 was determined as well as for N-methyllycodine (2), a derivative with the same nucleus, previously identified in P. saururus (IC(50) = 33.8 +/- 0.8 muM and 547.5 +/- 0.5 muM, respectively) and N-demethylsauroxine (3) whose inhibition in the actual conditions was better than the previously informed.