Savremene metode ekstrakcije koprive (Urtica dioica L.), sastav i primena ekstrakata / Contemporary methods of stinging nettle (Urtica dioica L.) extractions, composition and application of extracts

The main goals of this PhD thesis were investigation of chemical composition of stinging nettle leaves (Urtica dioica L.), application of different extraction techniques for isolation of biologically active compounds from leaves, investigation of their chemical composition and formulation of food product with addition of dried leaves and/or its extract. For those purposes, different analytical techniques were applied, i.e. GC/MS, GC/FID, UHPLCDAD/MS/MS, ICP-OES, direct mercury analyzer, AAS and spectrophotometry. Different classes of chemical compounds were detected and identified, such as: pigments (chlorophylls and carotenoids), terpenoids, phenolic and polyphenolic compounds, vitamins (vitamin C and B group) and fatty acids. For the purpose of isolation of biologically active compounds, different extraction techniques were applied: maceration, Soxhlet extraction, ultrasound (UAE), microwave (MAE) and supercritical (SFE) extraction. Preliminary conducted extraction, as well as total phenolics (TPC) and flavonoids (TFC) contents, showed that water was the most suitable solvent for further course of investigation. Water extracts were further analyzed regarding their chemical composition, antioxidant, cytotoxic and antimicrobial activities. Obtained result were compared in order to select the most efficient extraction technique. In the case of SFE, influence of pressure and temperature on extraction yield, composition and biological activity of prepared extracts were monitored. Exhausted plant material after SFE was used for further MAE extraction, while obtained extracts were analyzed to investigate chemical composition and biological activity. After conducted experiments and analysis, MAE extract was used for formulation of food product (bread) where it was added in different amounts in combination of without dried leaves. Obtained products were analyzed regarding their chemical composition, technological requirements and biological activity.