20.500.12556/DKUM-99782 Ekstrakcija in karakterizacija bioaktivnih spojin iz rakitovca (Hippophae rhamnoides) Extraction and characterization of bioactive compounds from sea buckthorn (Hippophae rhamnoides) V diplomskem delu smo obravnavali ekstrakcijo in karakterizacijo bioaktivnih spojin iz plodov rakitovca (Hippophae rhamnoides). Primerjali smo vpliv različnih ekstrakcijskih metod in topil na skupni ekstrakcijski izkoristek, vsebnost skupnih fenolnih spojin (angl. total phenolic content, TPC) in proantocianidinov (angl. proanthocyanidins, PAC) ter antioksidativno aktivnost pridobljenih ekstraktov. Izvedli smo hladno in vročo maceracijo ter ultrazvočno ekstrakcijo (angl. ultrasound-assisted extraction, UAE), kjer smo kot topila uporabili 75-odstotno vodno mešanico metanola, 75-odstotno vodno mešanico etanola in destilirano vodo. Poleg klasičnih ekstrakcijskih metod smo izvedli še ekstrakcijo s superkritičnim CO2 (angl. supercritical carbon dioxide extraction, SFE-CO2), kjer smo kot kotopilo uporabili etanol. Pridobljene ekstrakte smo ovrednotili gravimetrično ter spektrofotometrično z določitvijo skupnih fenolnih spojin po Folin-Ciocalteujevi metodi, proantocianidinov z butanol-HCl metodo in antioksidativne aktivnosti z metodo DPPH (2,2-difenil-1-pikrilhidrazil). Rezultati so pokazali, da izbira ekstrakcijske metode in topila pomembno vpliva na ekstrakcijski izkoristek ter sestavo in lastnosti pridobljenih ekstraktov. Največje izkoristke smo dosegli pri vroči maceraciji (41,0–46,9 %), sledili sta hladna maceracija (38,8–41,3 %) in UAE (33,3–35,4 %), medtem ko je SFE-CO2 dosegla najširši razpon izkoristkov (26,7–47,1 %). Ugotovili smo, da večji masni izkoristek ne pomeni nujno tudi višje vsebnosti ciljnih bioaktivnih spojin. Najvišjo vsebnost TPC smo določili pri ekstraktu vroče maceracije s 75-odstotnim metanolom (18,71 mg GAE/g materiala), najvišjo vsebnost PAC pri UAE s 75-odstotnim metanolom (4,88 mg PAC/g materiala), najvišjo antioksidativno aktivnost pa pri 75-odstotnem etanolnem ekstraktu hladne maceracije (21,79 % inhibicije). Vodni in superkritični ekstrakti so vsebovali bistveno manj polarnih bioaktivnih spojin. Rezultati kažejo, da ne moremo izpostaviti ene same optimalne ekstrakcijske metode za pridobivanje posameznih bioaktivnih spojin oziroma antioksidativne aktivnosti. Najvišje vrednosti pri posameznih analizah so namreč dosegale različne kombinacije ekstrakcijskih metod in topil. Nasprotno pa je SFE-CO2 zaradi svoje nepolarne narave in selektivnosti povsod dosegla najnižje vrednosti. In this thesis, the extraction and characterization of bioactive compounds from sea buckthorn (Hippophae rhamnoides) fruits were investigated. The effects of different extraction methods and solvents on the overall extraction yield, total phenolic content (TPC), proanthocyanidin content (PAC), and antioxidant activity of the obtained extracts were evaluated. Cold and hot maceration as well as ultrasound-assisted extraction (UAE) were performed using 75% aqueous methanol, 75% aqueous ethanol, and distilled water as extraction solvents. In addition, supercritical CO₂ extraction (SFE-CO2) was performed using ethanol as a co-solvent. The obtained extracts were evaluated gravimetrically and spectrophotometrically by determining the TPC using the Folin–Ciocalteu method, PAC using the butanol–HCl method, and antioxidant activity using the DPPH assay. The results showed that the selection of the extraction method and solvent significantly influenced the extraction yield, as well as the composition and properties of the obtained extracts. The highest overall extraction yields were achieved by hot maceration (41.0–46.9%), followed by cold maceration (38.8–41.3%) and UAE (33.3–35.4%), whereas SFE-CO2 exhibited the widest range of extraction yields (26.7–47.1%). It was demonstrated that a higher extraction yield does not necessarily correspond to a higher content of target bioactive compounds. The highest TPC was determined in the hot maceration extract prepared with 75% aqueous methanol (18.71 mg GAE/g material), the highest PAC content in the UAE extract prepared with 75% aqueous methanol (4.88 mg PAC/g material), while the highest antioxidant activity was obtained for the 75% aqueous ethanol cold maceration extract (21.79% inhibition). Water-based and SFE-CO2 extracts contained considerably lower amounts of polar bioactive compounds. The results indicate that no single extraction method can be identified as universally optimal for obtaining individual bioactive compounds or achieving the highest antioxidant activity. The highest values for individual analyses were obtained using different combinations of extraction methods and solvents. In contrast, SFE-CO2 exhibited the lowest values in all analyses under the applied conditions, which can be attributed to the selectivity of SFE-CO2 and its lower suitability for the extraction of polar bioactive compounds. rakitovec ekstrakcija fenoli proantocianidini antioksidativnost sea buckthorn extraction phenolic compounds proanthocyanidins antioxidant activity true true false Slovenski jezik Angleški jezik Diplomsko delo/naloga 2026-08-26 11:42:56 2026-09-11 08:17:13 2026-09-12 03:05:08 0000-00-00 00:00:00 2026 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 VS_Psenicnik_Tanja_2026.pdf VS_Psenicnik_Tanja_2026.pdf 1 A2244F6CE2F9091A159386B38893DE70 4c0a45f80eff34e50603e2da7a1d27440d5eb21f68818d5433ed6f3725813db1 93107e41-acfe-11f1-b668-00155d0001be https://dk.um.si/Dokument.php?lang=slv&id=212066 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0