A novel approach for efficient extraction and enrichment of phytochemicals with CO2-based switchable-solvent from pigeon pea leaves

A novel approach for synchronous extraction and enrichment of hydrophilic component and hydrophobic component with CO2-based switchable-solvent (SHS) from pigeon pea leaves was developed in the present study. After screening of SHS, N, N-dimethyl-cyclohexylamine (DMCHA)/water system was selected as the properest SHS for the extraction and enrichment process. To optimize this process, we conducted single factor experiments with the Box-Behnken design. The optimal parameters were as follows: solid-liquid ratio R (S/L) 40:1 (mg/mL), ultrasound time 15 min and bubbling CO2 time 79 min (0.5 mL/s). Under the circumstances, the extraction yields of representative flavonoid vitexin and stilbene cajaninstilbenes acid (CSA) reached 1.80 +/- 0.12 mg/g and 9.32 +/- 0.08 mg/g, respectively, which were 1.06 and 1.49 folds to those by the traditional methods. And the contents of target compounds vitexin and CSA in the enriched extracts were 2.3% and 12.1%, which increased above 6.76 and 4.58 folds to that in extracts using 65% ethanol-UAE. And the results suggested that the N, N-dimethyl-cyclohexylamine (DMCHA)/water system can be guaranteed for at least 5 cycles with relatively stable extraction yields of vitexin and CSA. Furthermore, a theoretical study using density functional theory was put into effect to explore the properties of SHS and their relationship with the vitexin and CSA. The mechanism study showed that SHS had higher biocompatibility with target compounds due to the H-bonds. The present method was an eco-friendly, promising, and sustainable alternative to extract and enrich simultaneously hydrophilic and hydrophobic phytochemicals from plant materials. (C) 2020 Published by Elsevier Ltd.

Automated summary

A novel method for synchronous extraction and enrichment of hydrophilic and hydrophobic components from pigeon pea leaves was developed, achieving higher extraction yields and target compound contents. The SHS used in the extraction process demonstrated stable extraction yields for at least 5 cycles and showed good biocompatibility with the target compounds. This method is an environmentally friendly, promising, and sustainable alternative for extracting and enriching phytochemicals from plant materials simultaneously.