20.500.12556/RUL-181289 Analiza vsebnosti oleuropeina, hidroksitirozola in tirozola v izdelkih iz listov oljke (Olea europaea) na slovenskem trgu Analysis of oleuropein, hydroxytirosole and tyrosole content in olive leaf (Olea europaea) products on the Slovenian market Listi oljke (Olea europaea L.) so pomemben vir bioaktivnih fenolnih spojin, med katerimi izstopajo oleuropein, hidroksitirozol in tirozol. Zaradi njihovega antioksidativnega delovanja narašča zanimanje za uporabo listov v prehranskih dopolnilih. Na slovenskem trgu je opazna velika raznolikost teh izdelkov glede na obliko (čaji, kapsule, tekoči pripravki) in vsebnost ključnih spojin, kar odpira vprašanja o njihovi dejanski kakovosti in skladnosti z deklaracijami. Namen magistrskega dela je bil ugotoviti vsebnost izbranih fenolov v komercialnih izdelkih, in v listih oljke slovenskega porekla. Preučevali smo liste treh sort oljk ('Buga', 'Pendolino', 'Istrska belica'), vpliv časa nabiranja (jesen, pomlad) in načina pridobivanja listov (sveži, postani listi) na vsebnost izbranih analitov. V ta namen smo razvili in validirali metodo HPLC za kvantifikacijo oleuropeina, hidroksitirozola in tirozola. Pri optimizaciji ekstrakcije smo preučevali vpliv topila (voda, etanol), čas ekstrakcije in velikosti delcev mletih listov na izplen fenolov. Vsi preiskovani parametri so imeli pomemben vpliv. Pri enostopenjskih postopkih smo najvišje vsebnosti oleuropeina (1,38 %) dosegli pri enourni ultrazvočni ekstrakciji listov oljke z velikostjo delcev < 1000 µm, ki je bila tudi najbolj ponovljiva. V vzorcih listov slovenskega izvora so na vsebnost fenolnih spojin pomembno vplivali sorta, letni čas in stanje rastlinskega materiala. Najvišje vsebnosti oleuropeina smo izmerili pri 'Istrski belici' (1,170 %) in pomladanskih svežih listih iz Oljarne Lisjak (2,387 %). Analize komercialnih izdelkov s slovenskega trga so pokazale velike razlike v kakovosti. Pri primerjavi s farmakopejskimi standardi vsebnosti oleuropeina (5,0 % za drogo in 16,0 % za suhe izvlečke) je le približno polovica vzorcev je ustrezala osnovnemu kriteriju kakovosti. Pri 7 od 9 deklariranih izdelkih pa so bile izmerjene vrednosti bistveno nižje od deklariranih. Priporočeni dnevni odmerki oleuropeina so se močno razlikovali, saj so deklarirane vsebnosti variirale od 18 do 150 mg na dan, razpon izmerjenih vsebnosti oleuropeina v priporočenem dnevnem odmerku je bil izjemno širok, in sicer od 0,31 do 530,74 mg na dan, kar potrjuje nezanesljivost nekaterih pripravkov. Na podlagi analize zaključujemo, da so prehranska dopolnila z listi oljke na slovenskem trgu zelo različne kakovosti in pogosto pomanjkljivo standardizirana glede na vsebnost ključnih bioaktivnih spojin. Razvita metoda HPLC in optimiziran postopek vodne ekstrakcije predstavljata uporabno orodje za nadaljnje raziskave in zagotavljanje večje varnosti potrošnikov. Olive leaves (Olea europaea L.) are an important source of bioactive phenolic compounds, with oleuropein, hydroxytyrosol, and tyrosol being particularly prominent. Due to their antioxidant activity, there is increasing interest in using olive leaves in dietary supplements. Despite their popularity, the Slovenian market exhibits considerable diversity in product forms (teas, capsules, liquid preparations) and the content of key compounds, raising concerns regarding their actual quality and compliance with label claims. The aim of this master’s thesis was to determine the content of selected phenolic compounds in commercial products and in olive leaves of Slovenian origin. The study examined three olive cultivars (‘Buga’, ‘Pendolino’, ‘Istrska belica’), the influence of harvesting season (autumn, spring) and leaf condition (fresh vs. stored) on the content of the selected analytes. For this purpose, an HPLC method was developed and validated for the quantification of oleuropein, hydroxytyrosol and tyrosol. During the optimization of extraction, the effects of solvent (water, ethanol), extraction time, and leaf particle size on the phenolic yield were studied. All investigated parameters were found to have a significantly impact. Among the single-stage procedures, the highest oleuropein content (1.38% w/w) was achieved using a one-hour ultrasonic extraction of leaves with particle size <1000 µm, which proved to be the most reproducable method. In leaves of Slovenian origin, phenolic content was significantly influenced by the cultivar, season, and condition of plant material. The highest oleuropein concentrations were measured in 'Istrska belica' cultivar (1.170% w/w) and in fresh spring leaves from Oljarna Lisjak (2.387% w/w). The analysis of commercial products revealed considerable variability in quality. When compared to Pharmacopoeia standards for oleuropein content (5.0% for herbal drug, 16.0% for dry extracts), only approximately half of the samples met the basic quality criteria. In 7 out of 9 products with declared values, the measured concentrations substantially deviated from them. Recommended daily doses of oleuropein varied significantly, with labelled contents ranging from 18 to 150 mg, while the actually measured values ranged from 0.31 to 530.74 mg per day. Based on the analysis, we conclude that olive leaf dietary supplements on the Slovenian market are of highly inconsistent quality and often insufficiently standardized regarding the content of the key phenolic ingredients. The development of HPLC method and optimized aqueous extraction represent useful tools for further research and for ensuring greater consumer safety. Olea europaea L. oleuropein hidroksitirosol HPLC vodna ultrazvočna ekstrakcija kakovost izdelkov Olea europaea L. oleuropein hydroxytyrosol HPLC water ultrasound-assisted extraction product quality true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-03-31 08:45:13 2026-03-31 08:45:32 2026-04-01 04:30:01 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 124931 31882.pdf 31882.pdf 1 FF61FC6E73C2D2EB24F8262E87746AEB e4515a506528aeaca1e79a3c50cbc68040203ff6be6c0ca994bcad8f0f48c2bf 18c559f9-2ccd-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=231605 Fakulteta za farmacijo 0 0 0