In-vitro digestion studies of rosemary, green tea and invasive knotweed species extracts: effect on their bioacessibility and antioxidant capacity

Tivadar, Eva (author), Pogačnik da Silva, Lea (mentor), Delgado Alves, Vitor (comentor)

The aim of this study was to evaluate the antioxidant capacity (AOC) of rosemary, green tea and shoot and root extracts of Japanese (F. japonica), Sakhalin (F. sachalinensis) and Bohemian (F. x bohemica) during a simulated in-vitro gastrointestinal digestion focusing on the influence of pH by DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (Ferric Reducing Antioxidant Power) tests and, for the knotweed plants, additionally by TPC (Total Phenolic Contents) tests. The digestion protocol was divided into two main sections, the gastric phase (GP) and the intestinal phase (IP), which in turn were subdivided into the initial and final stages of each section. Our study showed that the antioxidant capacity of both rosemary and green tea extracts, as measured by the DPPH assay, decreased from the GP to the final part of the IP. Evaluation with FRAP showed the opposite trend, suggesting that the change to an alkaline pH allows the release of phenolic compounds that have excellent antioxidant properties and act as reducing agents. Evaluation of the AOC of knotweed extracts measured by DPPH assay showed a drastic decrease in the observed parameter for knotweed shoot extracts in IP with almost no activity, while the scavenging ability of root extracts could still be observed in the same phase. FRAP showed that knotweed (especially the root extracts) acted as effective reducing agents and exhibited sustained antioxidant activity throughout the digestion protocol. We also discussed the bioavailability of knotweed extracts in relation to the available studies and the potential improvements to this parameter in terms of novel delivery systems. For example, encapsulation was suggested as a promising means to improve the bioavailability of the biocomponents contained in the studied plant extracts.

• Language: English
• Keywords: antioxidant capacity, in-vitro digestion, rosemary, green tea, knotweeds
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [E. Tivadar]
• Year: 2025
• PID: 20.500.12556/RUL-166814
• UDC: 612.3:547.9:66.094.3.097.8
• COBISS.SI-ID: 223960579
• Publication date in RUL: 27.01.2025

Secondary language

• Language: Slovenian
• Title: Ugotavljanje biorazpoložljivosti in antioksidativne učinkovitosti ekstraktov rožmarina, zelenega čaja in invazivnih dresnikov med simulacijo prebave in-vitro

Abstract

Namen naše študije je bil ovrednotiti antioksidativno učinkovitost (AOC) ekstraktov rožmarina in zelenega čaja ter ekstraktov poganjkov in korenik japonskega (F. japonica), sahalinskega (F. sachalinensis) in češkega (F. x bohemica) dresnika med in-vitro simulacijo prebave s poudarkom na preučevanju vpliva pH. Za preučevanje AOC rastlinskih ekstraktov smo uporabili metodi DPPH (2,2-difenil-1-pikrilhidrazil) in FRAP (železo-reducirajoča antioksidativna učinkovitost) ter za ekstrakte dresnikov dodatno še TPC (skupne fenolne spojine). Protokol prebave smo razdelili v dve glavni fazi, želodčno (GP) in intestinalno (IP), vsako od teh pa še v podkategorijo začetnega in zaključnega dela posamezne faze. Naša raziskava je pokazala, da se je AOC ekstraktov rožmarina in zelenega čaja, merjena z metodo DPPH, od začetka GP do konca IP znižala; metoda FRAP je pokazala ravno nasproten trend in nakazala, da sprememba pH iz kislega v bazično omogoči sprostitev fenolnih spojin, ki delujejo kot odlični reducenti. Pri ekstraktih poganjkov dresnikov je metoda DPPH pokazala drastično znižanje preiskovanega parametra, saj AOC črevesni fazi ni bilo možno zaznati. Nasprotno je bila ta pri ekstraktih korenik dresnikov še izmerjena. AOC, merjena z metodo FRAP, je pokazala, da ekstrakti dresnikov izkazujejo dobre reducirajoče sposobnosti, zlasti ekstrakti njihovih korenik, saj so skozi celoten potek simulirane prebave izkazovali podaljšano delovanje. S pomočjo znanstvene literature smo ovrednotili njihovo biorazpoložljivost in možne izboljšave s pomočjo obetavnih naprednih nosilnih sistemov, kot je enkapsulacija bioaktivnih spojin rastlin.

• Keywords: antioksidativna učinkovitost, in-vitro simulacija prebave, rožmarin, zeleni čaj, dresniki