Stereoselective phenolic coupling in Blechnum spicant: formation of 8–2′ linked (−)-cis-blechnic, (−)-trans-blechnic and (−)-brainic acids

In vivo administration experiments using stable (13C) and radio (14C) labeled precursors provide further evidence for vascular plant proteins engendering specific but distinct phenolic coupling modes, i.e. in this case for stereoselective 8–2′ coupling leading to the optically active lignans, (–)-blechnic and (–)-brainic acids.