Abstract:
Defatted raspberry seeds were used as an alternative source of antioxidants and ellagic
acid (EA) extracted using Natural deep eutectic solvents (NADES). In the preliminary study, the best
NADES combination (citric acid-betaine) and the most influential variables (temperature, time, and
NADES/plant ratio) were selected for the further optimization process. All samples were analyzed in
terms of total polyphenol, EA content, and antioxidant activity. Two sets of optimal conditions were
generated by response surface methodology. The first set (Opt1) was designed for higher conversion
of ellagitannins to EA while the latter set (Opt2) for higher EA content/100 g extract. Opt1 and
Opt2 had higher values for all investigated responses compared to 80% ethanolic extract but had a
lower conversion rate of ellagitannins to EA compared to acidified methanol extract. The third set of
parameters (Opt3) selected beyond the initial experimental domain was used to obtain a sample with
the highest EA content/100 g extract. Due to their nature, NADES extracts are ready to use and could
have various technological roles in products since they are antioxidants, acidifiers, and colorants.
NADES raspberry extracts exhibited higher anti-proliferative activity compared to ethanolic extracts
in terms of EC50 values. However, the main contributor of anti-cancer activity in NADES raspberry
extracts were individual NADES compounds and/or their newly formed NADES structure.
