Stepwise elution by high-speed counter-current chromatography combined with a modified macroporous resin to isolate and purify antioxidant phenolics from discarded jackfruit (Artocarpusheterophyllus Lam.) peels

Abstract

Combined with modified macroporous resin (MR), high-speed counter-current chromatography (HSCCC) was developed to separate and purify the antioxidant phenolics from waste jackfruit peels. First, the 4,4′-bis(chloromethyl)-1,1′-biphenyl was used to modify the commercially available adsorbent resin XAD-4 in order to enrich the antioxidant phenolics. Second, the resultant phenolics-rich fractions were further purified by HSCCC. In the separation process, the petroleum ether–ethyl acetate–methanol–0.1% acetic acid (5 : 5 : 3 : 7, v/v) upper phase was employed as an immobile phase. Afterwards, stepwise elution using petroleum the ether–ethyl acetate–methanol–0.1% acetic acid (5 : 5 : 3 : 7, v/v) lower phase was carried out during the initial 3.5 h, whereas the petroleum ether–ethyl acetate–methanol–0.1% acetic acid (5 : 5 : 6 : 4, v/v) lower phase was adopted for stepwise elution during the later 2.0 h. Four phenolics were obtained from 179 mg of the phenolics-rich fraction in a single run, including 41 mg chlorogenic, 27 mg gallic acid, 33 mg quercetin, and 29 mg catechin. ¹³C NMR, ¹H NMR, and ESI-MS were employed to identify their structures.