Effect of deep eutectic solvent’s characteristics on extraction and bioactivity of polyphenols from Sapodilla pulp

Abstract

In the present study, a sustainable and efficient deep eutectic solvent (DES)-based ultrasound-assisted extraction method for Sapodilla pulp polyphenols was developed. Seven different DESs prepared using carboxylic acid, polyol and amide were evaluated and compared with an aqueous-organic solvent mixture- acetone–water (50%)- the control used in this study. Low pH and high polarity markedly enhanced the recovery of the polyphenols in acid-based DESs. The highest yield was obtained with oxaline, followed by maloline and laline, as the presence of three OH groups considerably retarded the interaction between DES and target compounds, enhanced the viscosity and reduced the availability of H-bonding sites in glyceline and maline. Although the extraction rate was considerably slower in highly viscous DESs, the time required to attain the equilibrium was only marginally higher for oxaline and maloline than the acetone–water mixture. Reduced air incorporation due to high viscosity and strong H-bonding with DESs also substantially enhanced the storage stability of released antioxidants in DES. The low pH of carboxylic acid constituents and innate toxicity of urea at high concentration were responsible for high antimicrobial activity of acid, and amide-based DES extracts against Aspergillus and Bacillus. However, cell lysis and enzyme inhibitory properties of polyphenols were responsible for antimicrobial activities of polyol-based DESs and organic solvent-based extracts. However, the ability of fungi to metabolize the substrates effectively reduced DESs’ efficiency against the organism compared to bacteria. Therefore, these solvents have great potential as possible alternatives to conventional solvents health-related areas, such as food and medicines.