Leoligin formation in transformed hairy roots of Edelweiss (Leontopodium alpinum Cass.)

Lignans constitute a group of plant metabolites of which several compounds are known to possess pronounced biological activities. Leoligin, a lariciresinol derivative, has been recently isolated from the underground parts of Edelweiss (Leontopodium alpinum Cass., Asteraceae) and was shown to inhibit in vitro leukotriene biosynthesis and intimal hyperplasia of venous bypass grafts (Reisinger et al. 2009). As yet a synthesis of this complex structure is not available, and due to the low content (between 0.005 and 0.010 w%) in the small roots of field grown Edelweiss acquisition of the compound is laborious. Thus, the biotechnological production of leoligin might be an interesting alternative.

Edelweiss shoot cultures were transformed with Agrobacterium rhizogenes wild type strains to obtain hairy roots. A fast growing clone was treated with elicitors (silver nitrate, methyl jasmonate, yeast extract, and elevated sucrose concentration) and leoligin formation was quantified by a validated HPLC/PAD assay (w% of dry plant material). Untreated hairy roots were found to contain 0.0094 ± 0.0004 w% leoligin. By elicitation with either 200µM methyl jasmonate or 6% sucrose lignan content could be nearly doubled to 0.0162 ± 0.0008 w% and 0.0161 ± 0.0018 w%, respectively, although elicitor treatment led to slightly reduced biomass increase. After further clone selection and optimization of growth parameters the procedure could be an attractive option for the continuous, field culture-independent production of leoligin.

Reference:

[1] Reisinger U, Schwaiger S, Zeller I, Messner B, Stigler R, Wiedemann D, Mayr T, Seger C, Schachner T, Dirsch VM, Vollmar AM, Bonatti JO, Stuppner H, Laufer G, Bernhard D. (2009) Leoligin, the major lignan from Edelweiss, inhibits intimal hyperplasia of venous bypass grafts. Cardiovasc Res 82(3): 542 – 9.