Radial distribution of monomeric, dimeric and trimeric norlignans and their polymerization in Cryptomeria japonica heartwood.

The norlignan (NorL) content in extractives of sugi (Cryptomeria japonica) shows a decreasing tendency from the outer to the inner part of the heartwood (hW). The hypothesis, that this effect may be due to polymerization, which aggravates NorL extraction, has been explored in the present study. To this purpose, samples were collected and extracted from the outer, middle and inner parts of the hW. Fractionation procedures of NorL-oligomers by LH-20 column chromatography were established, and the fractions were characterized by advanced analytical methods such as HPLC-SEC and HPLC combined with electrospray ionization ion trap mass spectrometry (HPLC-ESI-ion-trap-MS). Agatharesinol and sequirin C were the most abundant compounds. Several individual NorL-dimers and -trimers were detected for the first time, and four kinds of NorL-dimers and seven kinds of NorLtrimers were semi-quantitatively analyzed by HPLC-ESIMS combined with selected ion monitoring (SIM). The oligomer contents show an increasing tendency from the outer part toward the middle and inner part of the hW, which accounts mainly for the monomeric NorL decrement in the same direction. [ABSTRACT FROM AUTHOR]