Stereoselective phenolic coupling in Blechnum spicant: formation of 8–2′ linked (−)-cis-blechnic, (−)-trans-blechnic and (−)-brainic acidsElectronic supplementary information (ESI) available: 13C-NMR spectra of (a) natural abundance (−)-trans-blechnic 1 acid, as well as (−)-trans-blechnic acids 1 obtained following administration of (b) [1-13C], (c) [2-13C] and (d) 3-13C]-phenylalanine 6 (1 mM) to B. spicant fronds for 5 days; all spectra were recorded under identical conditions. The relative carbon-13 enrichments noted were higher for (−)-brainic acid 2 than for (−)-trans-blechnic 1 due in large part to the much higher endogeneous levels of the latter in B. spicant. See http://www.rsc.org/suppdata/cc/b0/b008174o/

Abstract

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.