Variations in the chemical composition and content of salicylic glycosides in the bark of Salix purpurea from natural locations and their significance for breeding.

Willow bark is one of the few plant raw materials which contain natural active substances that have analgesic, fever-reducing, anti-inflammatory and anti-rheumatic effects. Salix purpurea, listed as widespread and common in many countries, belongs to the willow species with the highest content of salicylic compounds. The chemical composition and content of major salicylic glycosides (SGs) in the bark of S. purpurea genotypes from natural locations were investigated in this study to evaluate their applicability for pharmaceutical processing and creative breeding. Secondary metabolites were analyzed in bark extracts from 91 genotypes of S. purpurea selected from natural locations. The bark of all analyzed genotypes contained salicylic glycosides: salicin, salicortin and tremulacin; flavanones: naringenin 5-O-glucoside, naringenin 7-O-glucoside, naringenin, chalcone isosalipurposide and flavan-3-ol: catechin. Picein and populin were detected in 10% of the studied genotypes. The SG content of purple willow bark ranged from 3.04 to 10.96, pointing to high variations between S. purpurea genotypes. This study provides valuable breeding material and offers attractive prospects for the breeding of new and improved willow varieties. Varieties with the most desirable traits, grown under controlled conditions, can supply high-quality herbal materials for the pharmaceutical industry.