Extraction of chokeberry anthocyanins using natural deep eutectic solvents

Abstract

Fruits of chokeberry (Aronia melanocarpa (Michk) Elliot) contain high levels of phenolic compounds including anthocyanins which show strong antioxidant activities and reduce the risks of metabolic syndrome and age-related disease. Beyond internal use, chokeberry extracts can be incorporated into pharmaceutical formulations for topical application. The challenge in anthocyanin extraction is their limited chemical stability. In this study, an innovative eco-friendly method for the extraction of chokeberry anthocyanins was investigated. Anthocyanin extractions were performed using natural deep eutectic solvents (NaDES) coupled with ultrasound-assisted extraction. For this purpose, nine different NaDES composed of choline chloride as a hydrogen bond acceptor and organic acids, sugars, polyols, and an amide as hydrogen bond donors were screened. NaDES composed of choline chloride and malic acid was selected and used further for optimization of extraction conditions (sonication time, temperature, content of water in NaDES) by response surface methodology. Highly accurate predictive models for cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, cyanidin-3-O-arabinoside, and total anthocyanins were developed. Optimal conditions for simultaneously maximizing the anthocyanins extraction yield were 42.7 °C, 90 min, and 40% (w/w) water in NaDES. In the next stage of this study, the possibility of improving anthocyanins extraction yields at high extraction temperature by incorporating different concentrations of hydroxypropyl-β-cyclodextrin (HP-β-CD) into selected NaDES was investigated. The extraction yield was improved at HP-β-CD concentrations up to 3% (w/w). Developed methods can be useful for anthocyanins extraction from chokeberry fruit aimed to obtain standardized extracts for the application in pharmaceutical, cosmetic, and food industries.