Vrednotenje antioksidativne aktivnosti hidrogela in emulzije z izvlečkom lesa bele jelke (Abies alba)

Heric, Sara (author), Kočevar Glavač, Nina (mentor), Schoss, Katja (comentor)

Lignani so skupina naravno prisotnih rastlinskih polifenolov, ki imajo vlogo pri obrambi rastlin in uravnavanju rasti. Rastline z visoko vsebnostjo lignanov predvsem zaradi njihovih antioksidativnih lastnosti predstavljajo pomembno skupino za razvoj novih terapevtskih in kozmetično aktivnih snovi. Izvleček iz olesenelih delov bele jelke (Abies alba Mill.) ima visoko vsebnost lignanov, ki jih danes raziskujemo zaradi njihove bioaktivnosti. Ekstrahiramo jih med drugim s subkritično vodo, kar je tudi ena izmed tehnik, ki smo jo uporabili za pridobivanje preiskovanega izvlečka. Tekočine v sub- in superkritičnem stanju danes intenzivno raziskujemo za pridobivanje naravnih spojin v okviru okolju prijaznega procesa, saj se je zaradi povečane ozaveščenosti potrošnikov zanimanje za naravne spojine in trajnostne pristope v industriji povečalo. Namen magistrske naloge je bil ovrednotiti antioksidativne lastnosti na tržišču prisotnega izvlečka iz vej bele jelke Belinal® in laboratorijsko izdelanega izvlečka, pridobljenega s subkritično vodo, ki smo ju vgradili v emulzijo in hidrogel in skozi časovno obdobje šestih mesecev shranjevali pri 5 °C, 25 °C in 40 °C. Za ugotavljanje antioksidativne aktivnosti smo uporabili 2,2-difenil-1-pikrilhidrazilni (DPPH) test, za karakterizacijo kemijske sestave pa smo s tekočinsko kromatografijo visoke ločljivosti (HPLC) spremljali spreminjanje koncentracije sekoizolaricirezinola in izolaricirezinola, ki sta glavna lignana izvlečkov bele jelke. Izvleček, pridobljen s subkritično vodo, je imel nižjo antioksidativno aktivnost kot Belinal®, tako vgrajen v emulzijo (EC50 = 0,0616 μM) kot tudi v hidrogel (EC50 = 0,0479 μM), v vseh proučevanih razmerah. Antioksidativna aktivnost emulzije z Belinalom® je bila najvišja (EC50 = 0,0369 μM), tudi v primerjavi s hidrogelom (EC50 = 0,0397 μM). Izvleček, pridobljen s subkritično vodo, je imel obenem tudi nižjo koncentracijo preiskovanih lignanov. Koncentracija se s časom ni pomembno nižala pri nobenem od vgrajenih izvlečkov, kar dokazuje njihovo dobro aktioksidativno stabilnost v preizkušanih sistemih skozi čas pri različnih temperaturah. Na osnovi dobljenih rezultatov sklepamo, da ima Belinal® boljše antioksidativne lastnosti kot izvleček, pridobljen s subkritično vodo, obenem pa oba kažeta dobro oksidativno stabilnost pri proučevanih razmerah.

• Language: Slovenian
• Keywords: Abies alba, Belinal®, koncentracija lignanov, antioksidativna stabilnost, HPLC
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2025
• PID: 20.500.12556/RUL-169896
• Publication date in RUL: 14.06.2025

Secondary language

• Language: English
• Title: Evaluation of the antioxidant activity of a hydrogel and emulsion containing silver fir (Abies alba) wood extract

Abstract

Lignans are a group of naturally occurring plant polyphenols that play a role in plant defence and growth regulation. Plants with a high content of lignans, due to their antioxidant properties, represent an important group for the development of new therapeutic and cosmetically active substances. The extract from the woody parts of the white fir (Abies alba Mill.) has a high content of lignans, which are currently being researched for their bioactivity. They are being extracted, among other methods, with subcritical water, which is as well one of the techniques used for obtaining the investigated extract. Fluids in the sub- and supercritical state are intensively researched today to obtain natural compounds in an environmentally friendly process, as the interest in natural compounds and sustainable approaches has increased due to increased consumer awareness. The purpose of the master’s thesis was to evaluate the antioxidant properties of Belinal® white fir branch extract and the laboratory-produced extract obtained with subcritical water, which were incorporated into an emulsion and hydrogel, and then stored at 5 °C, 25 °C and 40 °C over a period of six months. To determine the antioxidant capacity, we used the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, and to characterize the chemical composition, we monitored changes in the concentration of secoisolariciresinol and isolariciresinol, which are the main lignans of white fir extracts, using high-performance liquid chromatography (HPLC). The extract obtained with subcritical water had a lower antioxidant activity than Belinal®, both incorporated in an emulsion (EC50 = 0,0616 μM) as well in the hydrogel (EC50 = 0,0479 μM), in all the studied conditions. The antioxidant activity of the emulsion with Belinal® was the highest (EC50 = 0,0369 μM), also compared to hydrogel (EC50 = 0,0397 μM). The extract with subcritical water also had a lower concentration of the monitored lignans. The concentration did not decrease with time significantly, for any of the incorporated extracts, which proves their good antioxidant stability in the tested systems over time at different temperatures. Based on the obtained results, we conclude that Belinal® has better antioxidant properties than the extract obtained with subcritical water, while at the same time, they both show good oxidative stability under the studied conditions.

• Keywords: Abies alba, Belinal®, lignan concentration, antioxidant stability, HPLC