Optimisation of polypropylene gycol extraction of bioactive compounds from olive leaves (Olea europaea L)

Listovi masline smatraju se jeftinim biljnim materijalom koji se može koristiti kao izvor visokovrijednih polifenolnih spojeva. U ovom radu su razvijene dvije ekološki prihvatljive metode za ekstrakciju bioaktivnih spojeva iz lista masline, koristeći netoksičnu smjesu vode, polipropilen glikola i mliječne kiseline kao otapalo. Za ekstrakciju polifeno la iz lista masline korištene su ultrazvukom potpomognuta ekstrakcija i ekstrakcija magnetnom miješalicom. Ispitan je učinak dvaju ekstrakcijskih parametara: omjer sastavnica otapala i omjer čvrstog prema tekućem (0,1-0,8 g/10 mL) na fenolni profil. Sadržaj oleuropeina, glavne bioaktivne komponente u listu masline, je određen pomoću RP-HPLC-DAD-a. Sadržaj ukupnih polifenola, flavonoida i fenolnih kiselina je određen spektrofotometrijskim metodama. Povećanje organskog otapala i biljnog materijala u ultrazvučnoj ekstrakciji rezultiralo je višim vrijednostima ukupnih polifenola i oleuropeina. Analizom fenolnih sadržaja dobivenih ekstrakata utvrđeno je da je konvencionalna metoda ekstrakcije uz magnetnu miješalicu učinkovitija u odnosu na ultrazvučnu ekstrakciju. Određeni su sadržaji polifenola uz magnetnu mješalicu pri 25 °C i 20´: ukupni polifenoli 21,45 mg OLE/mL, ukupni flavonoidi 0,24 mg QE/mL, ukupne fenolne kiseline 0,94 mg CAE/mL i oleuropein 6,47 mg/mL.Olive leaves are considered to be a cheap herbal material that can be used as a source of phenolic compounds with high added value. In this work, two environmentally friendly methods for the extraction of bioactive components from olive leaves were developed using non-toxic mixtures of water, polypropylene glycol, and lactic acid as a solvent. Ultrasoundassisted extraction and extraction with a magnetic stirrer of polyphenols from olive leaves were investigated and the phenolic contents of obtained extracts were compared. In this thesis, two extraction parameters were examined: ratio of solvent components and the ratio of solid to solvent (0,1-0,8 g/10 mL) on the phenolic profile. The content of oleuropein, the main bioactive compound in the extracts was determined using RP-HPLC-DAD. Total phenol, flavonoid, and phenolic acid content were determined by spectrophotometric methods. The increase of organic solvent and plant material in the ultrasound-assisted extraction resulted in increased total phenol content and oleuropein. The analysis of phenolic content of obtained extracts suggested that conventional extraction with a magnetic stirrer was more effective compared to an ultrasoundassisted extraction. Obtained contents of phenolics using magnetic stirrer at 25 °C and 20´ were: total phenol content 21,45 mg OLE/mL, total flavonoid content 0,24 mg QE/mL,total phemolic acid content 0,94 mg CAE/mL and oleuropein content 6,47 mg/mL