Magnetic boronic acid-functionalized Zn-MOFs separation combined with macroporous resin pre-enrichment for integrated purification of isoorientin from Thlaspi arvense L. leaves

Thlaspi arvense L. is a valuable industrial crop rich in bioactive flavonoids, specifically isoorientin and isovitexin. However, the efficient and selective separation of these isomers from complex plant matrices remains a significant challenge. In this study, a dual-stage purification strategy was developed by combining macroporous resin pre-enrichment with novel magnetic boronic acid-functionalized metal organic framework composites (Fe 3 O 4 @SiO 2 @BA Zn MOFs). The composite was synthesized via the coordinated assembly of 3,5-dicarboxyphenylboronic acid (BBDC) and zinc ions on magnetic silica cores. Systematic screening revealed X-5 resin as the optimal medium for preliminary enrichment, effectively removing major polar impurities. Subsequently, Fe 3 O 4 @SiO 2 @BA-Zn-MOFs were employed to selectively capture isoorientin via reversible boronate affinity. Under optimized conditions (pH 8.0, 120 min), the composite demonstrated high selectivity for isoorientin because of the formation of catechol-type ortho-dihydroxy moiety. The magnetic properties facilitated rapid solid liquid separation within 15 s. HPLC analysis revealed that the purity of isoorientin significantly improved from that of the crude extract to 90.28%. Furthermore, the magnetic adsorbent exhibited satisfactory stability and reusability, maintaining approximately 60% of its initial capacity after five consecutive cycles. This integrated approach provides an efficient and highly selective laboratory-scale strategy for the selective purification of high-value flavonoids from industrial crop byproducts and may provide a basis for future scale-up studies.