Simultaneous Enrichment and Separation of Four Flavonoids from Zanthoxylum bungeanum Leaves by Ultrasound-Assisted Extraction and Macroporous Resins with Evaluation of Antioxidant Activities

Quercitrin, hyperoside, rutin, and afzelin are the dominant flavonoids compounds from Zanthoxylum bungeanum leaves, and they play major roles in the antioxidant activity. Macroporous adsorption resin (MAR) treatment, a simple, low-cost and efficient method, was combined with ultrasound-assisted extraction (UAE) to enrich and purify these four flavonoids from Z. bungeanum leaves efficiently. The optimal conditions for UAE based on Response Surface Methodology (RSM) were determined to be an ethanol concentration of 60%, leaves size of 40 mesh, temperature of 50 degrees C and ultrasonic power of 400 W with four flavonoids contents of 120.84 mg/g. After the extraction process, five kinds of MARs (D4020, D-101, NKA-9, AB-8, and X-5) were tested through static adsorption/desorption to enrich and purify the ultrasonic-assisted extracts, and D-101 was selected as the most suitable resin. The optimal adsorption conditions were 5 bed volumes (BV) of sample solution with an initial concentration of 7.5 mg/mL and pH 5.0. Meanwhile, the optimal desorption parameters were 5 BV each of deionized water and 30% ethanol, then 10 BV 70% ethanol, and a flow rate of 2 BV/hr. Under the optimized conditions, the contents of quercitrin, hyperoside, rutin, and afzelin increased by 276.39%, 187.46%, 221.81%, and 288.45%, respectively, and the recovery yields were 85.47%, 73.53%, 81.35%, and 65.06%. In addition, laboratory preparative-scale separation indicated that the preparative separation of four flavonoids was feasible and easy. Moreover, the antioxidant activities of the purified products were significantly increased after enrichment. In conclusion, all of the results indicated that these methods are highly efficient, low cost, environmentally friendly and easy to scale up. Practical ApplicationThis study provided an environmentally friendly, rapid, and highly productive method for the extraction and purification of four active compounds from Zanthoxylum bungeanum leaves. The results can be used for the utilization of Z. bungeanum leaves as a kind of food supplement in an industrial setting.