Salix eleagnos Scop. – a novel source of antioxidant and anti-inflammatory compounds: Biochemical screening and in silico approaches

Abstract

Willow bark (Salix spp., Salicaceae) is traditionally used to treat pain and inflammation. Salix eleagnos Scop. is a widely spread in the Republic of Serbia, yet not much studied species. The aim of this study was to define the most suitable extraction technique for achieving highest yield and antioxidant activity of S. eleagnos bark extracts, to characterize their chemical composition and to assess the most active cyclooxygenase (COX) 1 and 2 inhibitors by in silico molecular docking analysis. Qualitative and quantitative characterization of extracts obtained by maceration, ultrasound (UAE) and microwave-assisted extraction (MAE) was carried out by High Pressure Liquid Chromatography (HPLC). Antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical (OH) scavenging assays. Molecular docking was conducted using AutoDock 4.2.3. package. Highest yield and antioxidant activity was obtained by MAE. HPLC analysis revealed the presence of chlorogenic, p-hydroxybenzoic, syringic, caffeic, p-coumaric, rosmarinic and trans-cinnamic acids, epicatechin, rutin, quercetin, naringenin and salicin. Docking results showed high binding affinity and good hydrogen bond interactions with active site residues of both COX-1 and COX-2 by flavonoids: quercetin, naringenin and epicatechin, and phenolic acids: rosmarinic and chlorogenic acids. These findings suggest that bark of S. eleagnos has great potential as source of antioxidant and anti-inflammatory compounds.