Application of high-performance liquid chromatography for research of salicin in bark of different varieties of Salix

Palmyra Kenstavičienė, Palma Nenortienė¹, Guoda Kiliuvienė¹, Andrejus Ževžikovas¹, Audronis Lukošius², Daiva Kazlauskienė¹

Department of Botany, Vilnius Pedagogical University, ¹Department of Analytical and Toxicological Chemistry, Kaunas University of Medicine, ²Department of Pharmacognosy, Kaunas University of Medicine, Lithuania

Key words: willow bark; salicin; high-performance liquid chromatography.

Summary. Willow (Salix L.) species are widely spread in Lithuanian natural dendroflora. Willow bark contains active substances known for anti-inflammatory properties and is known as a phytotherapeutic precursor of aspirin. Bark extracts are components of analgesic and antirheumatic preparations. Therapeutic effectiveness is associated with salicin (2-(hydroxymethyl)phenyl-β-D-glucopyranoside), which turns into salicylic acid. Increasing attention to natural preparations gives primary importance to research of plants. This study focused on 12 willow taxa and employed routine pharmacopoeia methods. High-performance liquid chromatography method was applied for the analysis of bark extractions. The investigation revealed that not all willow species accumulated a therapeutically sufficient amount of salicin. Bark samples were investigated after 1- and 2-year growth in autumn and spring. Salicin content ranged from 0.08 to 12.6%. Higher contents of active materials were determined in autumn and in 2-year-old willows. Certain willow taxa (Salix alba L., Salix mollissima L., Salix triandra L., Salix viminalis “Americana”, Salix dasyclados L.) possessed extremely low salicin amounts.

In the second year, analysis covered 32 willow species. Results indicated striking differences in salicin amounts (from 0.04% in Salix viminalis “Americana” to 12.06% in Salix acutifolia).

Willow species, plant age, and season should be considered when collecting medicinal plant material. The amount of salicylates in 2-year-old willow bark collected in autumn exceeded by 25% that in 1-year-old willow bark collected in spring. Bark of some analyzed willow species contained the amount of salicylates too low for using as anti-inflammatory or antipyretic remedy.

Correspondence to P. Nenortienė, Department of Analytical and Toxicological Chemistry, Kaunas University of Medicine, A. Mickevičiaus 9, 44307 Kaunas, Lithuania. E-mail: npalma@takas.lt

Received 8 October 2008, accepted 4 August 2009