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Introduction Hairy root cultures of Linum sp. are an alternative for the high production of lignans. Linum perenne is known to produce arylnaphthalene-type lignans such as justicidin B, isojusticidin and diphyllin. Objective To elucidate the presence of aryltetralin-type lignan diastereoisomers, besides the known arylnaphthalene-type lignans, in hairy roots of Linum perenne, and to determine the configurations of one diastereoisomer of 6-methoxypodophyllotoxin (6-MPTOX). Methods Lignans from hairy root cultures of Linum perenne were extracted and separated by HPLC. Arylnaphthalene-type lignans were identified by LC-MS, according to the literature. Two diastereoisomers of aryltetralin-type lignans were analysed by mass spectrometry and NMR spectroscopy. Results Numerous arylnaphthalene-type lignans (diphyllin-2-hexose-pentose, diphyllin-3-pentose and diphyllin-hexose) were identified in hairy root cultures. Methoxypodophyllotoxin, an aryltetralin-type lignan, was also identified, as well as one diastereoisomer. This aryltetralin-type lignan could be derived via 7-hydroxymatairesinol as a hypothetical biosynthetic pathway. The stereochemical configurations of aryltetralin isomers were determined. Conclusion Arylnaphthalene and two diastereoisomers of aryltetralin-type lignans are produced in Linum perenne hairy root cultures. Matairesinol, the precursor of justicidin B, also seems to be converted into 6-MPTOX via 7-hydroxymatairesinol. This is the first report of the stereochemical configurations of an aryltetralin-type lignan other than podophyllotoxin (PTOX). Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: A cDNA encoding a pinoresinol–lariciresinol reductase PLR (PLR-Lp1) was isolated from a cell culture of Linum perenne Himmelszelt accumulating the arylnaphthalene lignan justicidin B. The recombinant PLR-Lp1 prefers (+)-pinoresinol in the first reaction step, but (−)-lariciresinol in the second step. Therefore, it is the first PLR described with opposite enantiospecificity within the two reaction steps catalysed by PLRs. Hairy root lines transformed with an ihpRNAi construct to suppress plr gene expression show less mRNA accumulation for the plr-Lp1 gene and PLR enzyme activity. Justicidin B accumulation was reduced down to 24% in comparison to control lines showing the involvement of PLR-Lp1 in the biosynthesis of justicidin B. [Copyright &y& Elsevier]