New lignans identified in softwoods

Stefan Willför*, Patrik Eklund, Fredrik Sundell, Annika Smeds, Markku Reunanen, Sebastian Von Schoultz, Rainer Sjöholm, Reijo Sillanpää, Linda Nisula, Bjarne Holmbom

*Corresponding author for this work

Research output: Contribution to journalConference articleScientificpeer-review

Abstract

Research in our group has revealed that softwood knots, i.e. the branch bases inside tree stems, commonly contain 5-10% (w/w) of free lignans. A few lignans dominate in most industrially important softwood species, the most common lignans being 7-hydroxymatairesinol, secoisolariciresinol, lariciresinol, and nortrachelogenin. In addition, some minor lignans, of which some still are unidentified, are present in varying amounts in softwoods. We here report on the isolation and structural characterisation of two new 7-hydroxy divanillyl butyrolactol lignans, 1 and 2, which earlier, based solely on GC-MS analyses, incorrectly have been addressed as isomers of liovil in most softwoods. Some spruce species can contain up to 0.9% (w/w) of 1 and 2 in total. Additionally, we report on the isolation and structural characterisation of two previously unknown butyrolactone lignans, 3 and 4, which are present in amounts up to 0.5% (w/w) in, e.g. spruce species. The lignans were first extracted from softwood knots and then fractionated using appropriate techniques of normal and reversed-phase HPLC, reversed-phased TLC, and crystallisation from alcohol. The purified lignans were analysed using GC-FID, GC-EI-MS, LC-ESI-MS, and 1H and 13C NMR techniques. We conclude that knots in many softwood species constitute the richest known source of easily accessible lignans in nature. Our research has brought us close to a complete characterisation of all significant lignans in softwood knots. Nevertheless, some minor lignans still remain unidentified and should be characterised in the near future.

Original languageEnglish
Pages (from-to)421-425
Number of pages5
JournalAppita Annual Conference
Volume3
Publication statusPublished - 2005
MoE publication typeA4 Article in a conference publication
Event59th Appita Annual Conference and Exhibition, incorporating the 13th ISWFPC: International Symposium on Wood, Fibre and Pulping Chemistry - Auckland, New Zealand
Duration: 16 May 200519 May 2005

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