Arylnaphthalene and aryltetralin‐type lignans in hairy root cultures of Linum perenne, and the stereochemistry of 6‐methoxypodophyllotoxin and one diastereoisomer by HPLC‐MS and NMR spectroscopy

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.