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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