Optimization of luteolin separation from pigeonpea [Cajanus cajan (L.) Millsp.] leaves by macroporous resins

In the present study, the performance and separation characteristics of eight macroporous resins for the separation of luteolin (LU) from pigeonpea leaves extracts have been evaluated. The adsorption and desorption properties of LU on macroporous resins including AB-8, NKA-9, NKA-2, D3520, D101, H1020, H103 and AL-2 have been compared. AL-2 resin offers the best adsorption and desorption capacity for LU than other resins based on the research results, and its adsorption data at 25 °C fit best to the Freundlich isotherm. Dynamic adsorption and desorption experiments have been carried out with the column packed by AL-2 resin to optimize the separation process of LU from pigeonpea leaves extracts. The optimum parameters for adsorption were sample solution LU concentration 65.5 μg/ml, pH 5, processing volume 3 BV, flow rate 1.5 BV/h, temperature 25 °C; for desorption were elution solvent ethanol–water (50:50, v/v) 2 BV and followed by ethanol–water (60:40, v/v) 2 BV, and flow rate 1 BV/h. After treated with AL-2 resin, the LU content in the product was increased 19.8-fold from 0.129% to 2.55%, with a recovery yield of 78.54%. The results showed that AL-2 resin revealed a good ability to separate LU. Therefore, we conclude that results in this study may provide scientific references for the large-scale LU production from pigeonpea or other plants extracts.