Optimization of the Purification Process for C-Glycosyl Flavones from Phyllostachys edulis Leaves

A preparative purification process was developed for the enrichment of four C-glycosyl flavones from leaves of Phyllostachys edulis (Carrière) J.Houz., namely orientin, isoorientin, vitexin, and isovitexin. The crude P. edulis leaf extract was used as the feed material, and HPLC was employed for quantitative analysis. Macroporous resins and polyamide resins were compared in terms of their adsorption and desorption performance toward the target compounds. The results showed that D101 macroporous resin provided the best overall process suitability among the tested resins. The optimal purification conditions were an initial sample concentration of 10 mg·mL−1, a resin-to-sample loading ratio of 5:1 (g·g−1), a sample-loading flow rate of 4 BV·h−1, impurity removal with 15% ethanol, elution with 60% ethanol, an elution volume of 3 BV, and a 60% ethanol elution flow rate of 3 BV·h−1. After D101 resin purification, the yield of the four C-glycosyl flavones was 11.712 mg·g−1 relative to the crude extract, and their combined content in the D101-purified flavonoid-enriched powder reached 68.359 mg·g−1. Further purification using polyamide resin with a particle-size range of 0.15–0.25 mm and 40% ethanol resulted in the recovery of 16.128 mg·g−1 of the four C-glycosyl flavones relative to the D101-purified feed material, while their combined content in the polyamide-purified flavonoid-enriched powder reached 76.939 mg·g−1. This process provides a basis for the preparative separation and utilization of C-glycosyl flavones from P. edulis leaves.