8B-HYDROXYPTILOCAULIN, A NEW GUANIDINE ALKALOID FROM THE SPONGE MONANCHORA-ARBUSCULA

(+)-Ptilocaulin [1] and (+)-8b-hydroxyptilocaulin [3] have been isolat ed from a methanolic extract of the marine sponge Monanchora arbuscula . (+)-8b-Hydroxyptilocaulin is a new compound, the structure of which was elucidated by comparison of its spectral properties with those of 1. The complete assignment of all the H-1- and C-13-nmr signals of 1 a nd 3 is presented. The taxonomic implications of these results are dis cussed.