Carboxylic acid-based deep eutectic solvents combined with innovative extraction techniques for greener extraction of phenolic compounds from sumac (Rhus coriaria L.)

Abstract

Sumac (Rhus coriaria L.) is a traditional spice worldwide prized for its taste, odor, color, and promising bioactive compounds. The acidic natural deep eutectic solvents (NADESs) constituted of choline chloride with lactic acid (CHLA), acetic acid (CHAC), and tartaric acid (CHTA), and an addition of 20% water in the NADESs were tested for their efficiencies in extraction phenolic antioxidants from sumac. Distilled water, methanol, and ethanol were used as conventional solvents for comparison. The solvents combined with homogenate (HAE) or ultrasound (UAE) assisted extractions were first successfully applied to phenolic compounds recovery from sumac. TPC was found in the ranges of 44.52 ± 3.81–124.96 ± 3.43 mg GAE/g and 36.34 ± 0.89–114.53 ± 0.38 mg GAE/g for UAE and HAE, respectively. TFC was ranged from 4.95 ± 0.88–13.90 ± 0.35 mg ECE/g for UAE and from 4.08 ± 0.88–17.57 ± 0.09 mg ECE/g for HAE. The acidic NADESs generally exhibited the best recovery efficiency compared to the conventional solvents. CHAC and CHLA showed the best extraction efficiency in terms of the total phenolic content, flavonoid content, anthocyanin content, and antioxidant activity of the extracts obtained by HAE and UAE, respectively. No significant difference was found between HAE and UAE, proving that they are suitable extraction techniques to assist the acidic NADESs for the best recovery of phenolic compounds from sumac. HPLC analysis revealed that the extracts obtained with acidic NADESs, particularly CHAC and CHLA, showed higher contents of phenolic compounds compared to the extracts obtained with conventional solvents. The outcomes of the study revealed that the acidic NADESs and the proposed extraction techniques could be an excellent alternative for the greener extraction of phenolic compounds from plants.