Biološki potencijal i hemijska analiza vrsta roda Salix L. (Salicaceae) sa teritorije Republike Srbije | Biological potential and chemical analysis of species from the genus Salix L. (Salicaceae) from the territory of Republic of Serbia

The genus Salix belongs to the family Salicaceae and comprises about 450 species worldwide, out of which 18 grow in the Republic of Serbia. Willow bark exhibits anti-inflammatory, anti-rheumatic, analgesic and antipyretic effects through synergistic action of its main ingredients -glycosidesalicin, phenolic and flavonoid compounds. Aims of this paper were to analyse the impact of classical and modern extraction methods on chemical composition and biological activities of extracts of different willow species, determine the differences in the amount of active compounds and biological potential between bark and leaf extracts within the same willow species, as well as between extracts of various species. The analysis included 92 bark and leaf extracts of eight species from the genus Salix, obtained by different extraction methods (maceration, ulrasound and microwave assisted extraction) and conditions (solvent, time, particle size). Total phenolics and flavonoids content, as well as antioxidant activity were determined spectrophotometrically. Chemical characterization was carried out by high performance liquid chromatography (HPLC). Cyclooxygenase (COX-1 and COX-2) and acetylcholine esterase (AChE) inhibitory potential of compounds isolated from the extracts was examined by in silico method of molecular docking. Greater number of individual components in highest concentration, as well as exracts with stronger hydroxyl radical scavenging potential were obtained by modern extraction methods. Classical method of maceration with 70% ethanol (v/v) was more suitable for obtaining extracts with higher DPPH radical scavenging activity in the vast majority of tested species.In half of the analysed species leaf extracts inhibited hydroxyl radicals more than bark. Higher amount of individual compounds in bark or leaf extracts depended on the species itself. S. alba exhibited the strongest antioxidant activity, whereas S. fragilis had the most diverse chemical composition. Strong COX-1 and COX-2 inhibitory potential of flavonoids quercetin, naringenin and epicatechin, as well as chlorogenic acid among phenolic acids was determined by in silico molecular docking analysis. Molecular docking studies also demonstrated the inhibitory activity of epicatechin, salicin and chlorogenic acid toward AChE. The obtained results indicate that not only bark, but willow leaf as well could be used as source of significant phytochemicals and also the possibility of exploitation of willow species that are not commercially used as medicinal raw material for isolation of antioxidants and pharmacologycally active substances.