Simultaneous Hydrolysis of Ellagitannins and Extraction of Ellagic Acid from Defatted Raspberry Seeds Using Natural Deep Eutectic Solvents (NADES).

Nemanja Teslić,Alexandre Paiva,Anamarija Mandić,Filipa Santos,Filipe Oliveira,Alena Stupar,Milica Pojić,Aleksandra Cvetanović Kljakić,Ana Rita C Duarte,Aleksandra Mišan,Branimir Pavlić

doi:10.3390/antiox11020254

Nemanja Teslić, Alexandre Paiva + Show 9 more

Open Access

https://doi.org/10.3390/antiox11020254

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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.

Highlights

Introduction published maps and institutional affilIn 2019, Serbia was the third-largest raspberry (Rubus idaeus L.) producer in the world, with total annual fruit production of 1.20 × 105 tons [1]
From all prepared acidic Natural deep eutectic solvents (NADES), citric acid:betaine:water (CA:BET:H2 O) with molar ratio 2:1:2 exhibited the highest concentration of ellagic acid (EA) (75.17 as mg/100 DW of defatted raspberry seeds—DRS; 3.82 mg/solvent mL) even though NADES like tartaric acid:betaine (TA:BET) and malic acid:betaine (MA:BET) had the same statistical significance (Table 1)
The highest amount of total polyphenols with statistical significance was observed for NADES created from lactic acid:betaine:water (LA):BET:H2 O but with a molar ratio

Summary

Introduction

In 2019, Serbia was the third-largest raspberry (Rubus idaeus L.) producer in the world, with total annual fruit production of 1.20 × 105 tons [1]. The processing of fresh raspberries during the production of jams, fruit pulp, juices, and other similar products generates a large number of seeds, which are currently underutilized in Serbia. RS are a rich source of secondary plant metabolites such as polyphenols which are present in free, soluble bond (esterified or glycosylated), and insoluble-bond forms [3]. One of the most important polyphenols from RS is ellagic acid (EA) due to its broad spectrum of biological effects such as antioxidant, anti-carcinogenic, anti-obesity, anti-inflammatory and anti-angiogenic, anti-neurodegenerative, hepatoprotective activity, mainly evaluated in vitro [4,5]. The wide range of EA bioactivities is mainly attributed to its ability to scavenge free radicals in tissues, decreasing or preventing iations

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