Substituent effects of phenylboronic acid-functionalized resins in pH-controlled separation of catecholic flavonoids

Abstract Gel resins modified with different phenylboronic acid derivatives were prepared for selective separation of catechol-containing flavonoids. The phenylboronic acid gel (PBA-gel) resins showed pH-dependent adsorption and release of catechol-containing flavonoid quercetin. Under optimal pH control, the PBA-gel resins exhibited high quercetin binding capacity of up to 120 mg/g of resin and demonstrate quantitative release of the specifically bound quercetin. In addition, the recyclability of PBA-gel resin was confirmed by repeated binding and hydrolysis of quercetin with no significant loss of capacity during at least five cycles, showing great potential of PBA-gels as practical tools for selective separation of catechol-containing flavonoids.