Ultrasound-assisted extraction optimisation and biological effects of black medic extract (Medicago lupulina L.)

Biljni polifenoli su predmetom mnogobrojnih istraživanja zbog svojih pozitivnih učinaka na ljudski organizam. U ovom diplomskom radu određeni su uvjeti optimalne ekstrakcije ukupnih polifenola iz hmeljaste vije pomoću Bex-Behnken dizajna. Uvjeti su određivani s obzirom na maseni udio glicerola u otapalu, temperaturu i vrijeme ekstrakcije, a sadržaj polifenola određivan je spektrofotometrijski. Zaključeno je da su optimalni uvjeti 60%-tni udio glicerola, temperatura od 80 °C te vrijeme ekstrakcije od 20 mina. Dobiveni optimalni ekstrakt dalje je korišten u biološkim testovima ispitivanja aktivnosti inhibicije enzima tirozinaze, lipoksigenaze i elastaze te u β-karoten linoleatnoj analizi za određivanje antioksidativne aktivnosti ekstrakta. Ekstrakt pokazuje određenu sposobnost inhibicije tirozinaze, lipoksigenaze i elastaze, a njegova antioksidativna aktivnost nadmašuje onu butil-hidroksianisola koji je korišten kao pozitivna kontrola.Plant polyphenols have been the subject of numerous studies due to their positive effects on the human body. In this diploma thesis, the conditions of optimal extraction for total polyphenols from black medic were determined using Bex-Behnken design. Conditions were determined with respect to glycerol concentration in the solvent, temperature and extraction time, and polyphenol content was determined spectrophotometrically. It was concluded that the optimal conditions were a 60% glycerol concentration, a temperature of 80 C and an extraction time of 20 min. The obtained optimal extract was further used in biological assays to test the inhibition activity of the enzymes tyrosinase, lipoxygenase and elastase and in β-carotene linoleate analysis to determine the antioxidant activity of the extract. The extract shows a certain ability to inhibit tyrosinase, lipoxygenase and elastase, and its antioxidant activity surpasses that of butylhydroxyanisole which was used as a positive control