Design and optimization of isolation process of valuable compounds from horse chestnut (Aesculus hippocastanum L.)

Navadni divji kostanj (Aesculus hippocastanum L.) je mogočno drevo, ki sodi med najbolj prepoznavne in zanimive drevesne vrste pri nas. Po svetu ga gojijo zlasti kot okrasno drevo, po zaslugi prisotnih bioaktivnih molekul v posameznih delih drevesa pa postaja vse pomembnejša surovina v kozmetični in farmacevtski industriji. Cilj magistrske naloge je bil optimizirati postopek izolacije vrednih spojin iz semen divjega kostanja z uporabo metode odzivnih površin z zasnovo Box-Behnkenovega načrtovanja. Proučevali smo različne ekstrakcijske tehnike, pri čemer je bil poudarek na okolju prijaznejših metodah, kot sta ekstrakcija s podkritično vodo in ekstrakcija z nadkritičnim CO2. Dobljene ekstrakte smo analizirali s spektrofotometričnimi in kromatografskimi metodami (HPLC, GC). Določevali smo vsebnost celokupnih fenolov, celokupnih ogljikovih hidratov, celokupnih escinov, maščobnih kislin (linolna, oleinska, palmitinska in stearinska kislina) in antioksidativno aktivnost ter prisotnost sladkorjev (glukoza, fruktoza, celobioza) in njihovih derivatov (5-HMF, furfural, levulinska kislina). Optimalni pogoji ekstrakcije s podkritično vodo za dosego čim višjih izkoristkov ekstrakcije in ekstraktov bogatih z escini ter zadovoljivimi vrednostmi ostalih vrednih spojin so sledeči: temperatura 150 °C, čas ekstrakcije 18,71 min in razmerje topilo-material 25,5 mL/g. Za tako optimizirane pogoje smo eksperimentalno določili izkoristek ekstrakcije 93,14 % in vsebnost celokupnih escinov 40,56 mg/g semen.The horse chestnut (Aesculus hippocastanum L.) is a mighty tree that is one of the most recognizable and interesting tree species in Slovenia. It is grown around the world mainly as an ornamental tree, due to the bioactive molecules present in different parts of the tree, it is becoming an increasingly important raw material in the cosmetics and pharmaceutical industries. The aim of the master\u27s thesis was to optimize the process of isolation of valuable compounds from horse chestnut seeds using the response surface methodology with the Box-Behnken design. Various extraction techniques were studied, with an emphasis on more environmentally friendly methods such as subcritical water extraction and supercritical CO2 extraction. The obtained extracts were analyzed by spectrophotometric and chromatographic methods (HPLC, GC). The content of total phenols, total carbohydrates, total escins, fatty acids (oleic, stearic, palmitic and linolenic acid), antioxidant activity and the presence of sugars (glucose, fructose, cellobiose) and their derivatives (5-HMF, furfural, levulinic acid) were determined. The optimal conditions of subcritical water extraction for achieving the highest possible extraction yields and extracts rich in escins and satisfactory values of other valuable compounds are as follows: temperature 150 °C, extraction time 18.71 min and solvent-solid ratio 25.5 mL/g. For such optimized extraction conditions, the extraction yield of 93.14% and the total escin content of 40.56 mg/g of material were experimentally determined