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Cilj ovog istraživanja bio je optimirati uvjete ubrzane ekstrakcije otapalima pri povišenom tlaku (ASE) za izolaciju sterola i pentacikličkih triterpenoida iz korijena koprive. Varirani su temperatura (70 do 150 °C), statičko vrijeme ekstrakcije (5 do 15 min) i broj ciklusa ekstrakcije (2 do 4) pri čemu je prema Box–Behnken dizajnu s 5 centralnih točaka dobiveno 17 uzoraka lipidne frakcije. U svim uzorcima određen je prinos lipidne frakcije te je ispitan sastav sterola i pentacikličkih triterpenoida primjenom plinske kromatografije. Prinos lipidne frakcije određen je u rasponu od 0,39 do 1,63 %. Identificirano je ukupno 12 spojeva iz skupine sterola i pentacikličkih triterpenoida: kampesterol, kampestanol, stigmasterol, β-sitosterol, Δ5-avenasterol, cikloartenol, obtusifoliol, 24-metilen cikloartenol, citrostadienol, α-amirin, β-amirin i β-amirin acetat. Udio ukupnih sterola i pentacikličkih triterpenoida određen je u rasponu od 43,50 do 78,26 mg 100 gˉ¹, a najzastupljeniji spoj u svim uzorcima bio je β-sitosterol (prosječna vrijednost udjela 50,21 mg 100 gˉ¹). Rezultati statističke analize pokazali su da svi ispitani uvjeti ekstrakcije imaju značajan utjecaj na udio ukupnih sterola i pentacikličkih triterpenoida. Optimalni uvjeti ASE pri kojima se dobivaju najveći prinosi sterola i pentacikličkih triterpenoida izoliranih iz korijena koprive su 150°C/5 min/4 ciklusa. The aim of this study was to optimize the conditions of accelerated solvent extraction (ASE) for the isolation of sterols and pentacyclic triterpenoids from nettle root. The temperature (70 to 150 °C), static extraction time (5 to 15 min) and number of extraction cycles (2 to 4) were varied and 17 samples of the lipid fraction were obtained according to the Box-Benkhen design with 5 central points. In all samples the yield of lipid fraction and the composition of sterols and pentacyclic triterpenoids by gas chromatography were determined. The yield of lipid fraction was determined in the range of 0.39 to 1.63%. A total of 12 compounds were identified from the group of sterols and pentacyclic triterpenoids: campesterol, campestanol, stigmasterol, β-sitosterol, Δ5-avenasterol, cycloartenol, obtusifoliol, 24-methylene cycloartanol, citrostadienol, α-amyrin, β-amyrin and β-amyrin acetate. The content of total sterols and pentacyclic triterpenoids ranged from 43.50 to 78.26 mg 100 gˉ¹, and the most abundant compound in all samples was β-sitosterol (mean content value 50.21 mg 100 gˉ¹). The results of statistical analysis showed that all studied extraction conditions had significant influence on the content of total sterols and pentacyclic triterpenoids. The optimal ASE conditions at which the highest yields of sterols and pentacyclic triterpenoids isolated from nettle root are obtained are 150 °C/5 min/4 cycles. |
