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Abstract: The present study aims to extract active components from pigeon pea leaves by ionic liquid-based microwave-assisted extraction (ILMAE) for quantitative analysis. Compared with ionic liquid-based heating extraction (ILHE) and ultrasonic-assisted extraction (ILUAE), ILMAE exhibited higher extraction efficiency. A series of 1-alkyl-3-methylimidazolium ILs with different anions and alkyl chain lengths of cations were investigated, and 1-butyl-3-methylimidazolium bromide ([C4MIM]Br) solution was selected as extractants. Subsequently, ILMAE parameters were optimized, and the optimized conditions were [C4MIM]Br concentration 0.75M, extraction temperature 60°C, solvent to solid ratio 12:1mL/g, and irradiation time 7min. Under the optimal conditions, the extraction efficiency increased by 11.0–38.9% compared with ILHR and ILUAE, and the recovery achieved more than 95.3%. Furthermore, a rapid analysis method, HPLC-DAD with an UPLC column, was established and validated. This method exhibited satisfactory linearity (r 2 >0.999), precision (RSD<4.6%) and recovery (97.14–103.38%), and was successfully applied for the quantification of nine components in pigeon pea leaves within 25min. The results obtained provide a fast and safe method for determination of active components in pigeon pea leaves. [Copyright &y& Elsevier]

A novel approach for synchronous extraction and enrichment of hydrophilic component and hydrophobic component with CO 2 -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 CO 2 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. Image 1 • This paper developed a novel approach for efficient and recyclable extraction and enrichment of phytochemicals from the disused pigeon pea leaves in one solvent system. • The mechanism study showed that SHS had higher biocompatibility with target compounds due to the H-bonds using the density functional theory. • The switchable solvents have usually been used in the extraction of oil. Moreover, the exploit of SHS considering bioactive compounds from plants material has hardly been reported yet. [ABSTRACT FROM AUTHOR]