Caffeine is odorless, bitter taste substance which can be naturally found in coffee, cocoa, tea leaves, and is intentionally added in food and pharmaceutical products. It can also be found in surface water in small concentrations where is often used as an excellent indicator of human waste. The aim of the work is determination of caffeine content in food, beverages, analgesics and surface water using solidphase extraction followed by high-performance liquid chromatography (HPLC). Caffeine content was determined in 12 commercial tea and coffee products, non-alcoholic energy drinks and food, 5 combined preparations of analgesics and the Danube samples collected from 7 representative locations. The results showed that caffeine content in food ranged 5,6-158 mg/100 g, tea samples 24,71-30,81 mg/100 ml, coffee samples 1328-3594 mg/100 g, energy drinks 9,69-30,79 mg/100 ml and in the Danube samples 15,91-306,12 ng/l. Caffeine content in combined commercial formulations of non-narcotic analgesics of all brands did meet specifications. The data suggested that the proposed HPLC method can be used for routine determination and control of caffeine content in different matrices.

Contents of twelve selected bioactive substances and antioxidant potential of Salix caprea L. extracts were compared in its two vegetative organs (bark and leaves) and in terms of different ethanol/water mixtures used for extraction (30-70% aq, ethanol) and extraction time (30 min; 24, 48 and 72 h). The extracts were characterized by High Pressure Liquid Chromatography (HPLC), and total phenolics and flavonoids were determined spectrophotometrically. All secondary metabolites identified in Salix caprea L. extracts (gallic, chlorogenic and vanillic acid, epicatechin, rutin, quercetin and naringenin) were found more accumulated in bark. Salicin and p-hydroxybenzoic acid were detected in bark and ferulic, trans-cinnamic and p-coumaric acid in leaves extracts only. Rutin was most abundant bioactive compound both in bark (1.71 g/100 g of de) and leaves extracts (0.434 g/100 g of de). Bark extract with highest bioactive substances contents was obtained with 70% aq. ethanol as most suitable solvent during extraction time of 48 h. Molecular docking showed salicin to have similar affinity toward COX-2 as acetylsalicylic acid, but lower toward COX-1.

Willow bark (Salix spp., Salicaceae) is a traditional analgesic and antirheumatic herbal medicine. The aim of this study was to evaluate and compare the phytochemical and antioxidant profiles of leaf and bark extracts of six species of the genus Salix obtained by ultrasound-assisted extraction (UAE) and to examine the inhibitory potential of target bioactive compounds against two inflammatory mediators, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), through in silico molecular docking. The total phenolic and flavonoid content of the extracts was estimated using spectrophotometric methods and the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and hydroxyl radical (•OH) scavenging assays. Chemical profiling of extracts was carried out using high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD). Principal component analysis (PCA) was performed to differentiate the sample extracts based on their phytochemical profiles and amounts of target bioactive compounds. Chemical composition varied among the analyzed willow species and also among the plant organs of the same species. The major bioactive compounds of the extracts were salicin, chlorogenic acid, rutin and epicatechin. The extracts exhibited significant DPPH● and ●OH scavenging activities. Results of molecular docking revealed that chlorogenic acid had the highest binding affinity toward TNF-α and IL-6. UAE extracts represent valuable sources of antioxidant and anti-inflammatory compounds.