Separation of pinostrobin from pigeon pea [Cajanus cajan (L) Millsp.] leaf extract using a cation exchange resin for catalytic transformation combined with a polyamide resin

•A method for catalytic transformation and separation of pinostrobin was developed.•Cation exchange resins was used as a catalyst for enhance the content of pinostrobin.•Polyamide resin was used for the separation of pinostrobin from pigeon pea extract.

An efficient continuous system for separation of pinostrobin from pigeon pea leaf extract using a cation exchange resin column (fixed-bed column reactor) connected to a polyamide resin column (fixed-bed column separator) was developed in this study. An NKC-9 cation exchange resin, with a styrene divinyl benzene matrix and –SO3– functional groups, was used as a catalyst to transform pinostrobin chalcone into piostrobin, with a dynamic transformation efficiency of 97.67 ± 1.82%. A polyamide resin column was used to adsorb pinostrobin from the pigeon pea leaf extract solution after the transformation reaction, and the most optimal condition was identified. After adsorption equilibrium, 30–70% ethanol was injected into the polyamide resin column as a desorption solvent, from which 50–70% ethanol eluates were collected as the final product and 30–40% ethanol was used to wash out impurities. This system greatly improved production, yielding a 24.67-fold increase in pinostrobin content in the dry product from 2.32 ± 0.16% to 57.23 ± 1.18%, and a final recovery of pinostrobin of 151.12 ± 1.53%.

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