Simultaneous extraction of natural organic acid and flavonoid antioxidants from Hibiscus manihot L. flower by tailor-made deep eutectic solvent

Deep eutectic solvents (DESs) have been regarded as a substitute extraction solvent for conventional organic reagents due to their low toxicity and unique solubility. In this study, fifteen choline chloride-based DESs were prepared and successfully integrated with microwave-assisted extraction (MAE) technique for extracting Hibiscus manihot L. flowers natural antioxidants. The selected DES exhibited superior extraction performance than those by water and 60% ethanol. After statistical optimization by single-factor experiments, Taguchi orthogonal design and response surface methodology, the maximal extraction yields of ten natural antioxidants reached 0.880, 0.328, 0.176, 0.243, 5.143, 4.098, 4.852, 0.171, 0.509 and 0.303 mg/g, which was 1.42–1.94 folds to those by conventional extraction media and methods. In addition, ten natural antioxidants were enriched and recovered with a satisfactory recovery yield of 88.45%–92.02%, and the regenerative DES could be recycled at least four times. Overall, this study established a green, safe, high-efficiency and sustainable alternative for efficiently extracting bioactive ingredients from plant matrices.