Localization of ferruginol, a diterpene phenol, in Cryptomeria japonica heartwood by time-of-flight secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was applied to the investigation of heartwood extractives in Sugi (Cryptomeria japonica). Sugi heartwood tissue generated secondary ions that were not produced from sapwood tissue by TOF-SIMS. Among the peculiar ions generated from heartwood, two positive ions of m/z 285 and 301 were remarkable due to their appearance in a larger mass range and with a high intensity. These two ions were not generated from heartwood tissue preextracted with n-hexane, and the n-hexane extract of Sugi heartwood produced both ions. Gas chromatography-mass spectrometry of the n-hexane extract demonstrated that ferruginol, a diterpene phenol, the molecular weight of which is 286, constituted one of the predominant constituents of the extract. Authentic ferruginol also generated both ions by TOF-SIMS. The molecular formula of the m/z 285 ion generated from Sugi heartwood tissue was estimated to be C20H29O, which corresponds well with that of ferruginol, i.e. C20H30O, by peak identification. All these results strongly suggest that the m/z 285 ion generated from Sugi heartwood tissue originated significantly from ferruginol in Sugi heartwood. By TOF-SIMS imaging, the m/z 285 ion was detected uniformly in the tracheid cell walls, in the cell walls of the axial parenchyma cells and ray parenchyma cells, and also inside these parenchyma cells. These results indicate that ferruginol was distributed almost evenly in Sugi heartwood tissue.