Due to their anti-inflammatory and analgesic properties, salicylates are medically interesting phenolic compounds [1]. In some patients, asperin, a synthetic derivative of salicin (β-D-glucoside of 2-hydroxybenzyl alcohol), induces more side effects than salicin [1]. Thus, herbal drugs could be excellent alternatives to asperin. The leaves of dark-leaved willow (Salix myrsinifolia) contain salicylates (salicin and its derivatives) [2], and are therefore a promising source of herbal drugs. The aim of the present study was to clarify the impact of fertilization on leaf biomass and salicylates in four dark-leaved willow clones.
Willows were established from cuttings in May 2002 and were grown on plastic mulch in field trials in Eastern Finland. Two fertilization treatments were used: 0 and 150kg (N)/ha. In August 2004, leaves were collected and air-dried. Soluble phenolics were extracted with methanol and quantified using HPLC/DAD [3].
Results showed that fertilization increased significantly leaf biomass (g plant-1, dw) (F =6.458, DF=1, P <0.05) and concentrations (mg/g, dw) of leaf salicortin (a derivative of salicin) (F =6.098, DF=1, P <0.05) and total salicylates (F =4.424, DF=1, P <0.05). The increased production of other phenolics (chlorogenic acid and quercetin-3-galactoside) did not limit the salicylate accumulation. However, most salicylates varied quantitatively among clones, and clones also responded differently to fertilization (P <0.05). Thus, the selection of clones for cultivation should be made with care.
Acknowledgements: The Academy of Finland (project no. 64308), University of Joensuu.
References: 1. Pierpoint, W.S. (1994), Adv. Bot. Res. 20: 163–235. 2. Julkunen-Tiitto, R., Meier, B. (1992), Planta Med, 58: 77–80. 3. Julkunen-Tiitto, R. et al. (1996), Trees-Struct. Funct 11: 16–22.
