Adsorption Separation for the Extracts from Ginkgo biloba Leaves Using Intermediate Polarity Resins

Abstract

An adsorption separation method using intermediate polar resins (Amberlite XAD‐7HP) was applied for concentrating the active ingredients from Ginkgo biloba leaves. First, the crude G. biloba L. extracts were prepared using a Soxhlet extractor operated under an optimal extraction condition (using 160 mL of 70% ethanol aqueous solution for 3 h per 10 g dry leaves). The extraction yield was 25–30% and the purity was 2.5–3.0 wt.% for flavonoid glycosides and 0.5–1.0 wt.% for terpene lactones. Before the column operation, the extracts were dissolved in 10% ethanol and used as the feed solution, which led to a 1.5–2.0 fold concentration and a 10–20% loss for both active ingredients. Then, the column was operated under four steps, i.e., adsorption, washing, elution, and regeneration, in sequence. The results show that using the eluent with a high ethanol concentration (≥70%) in the isocratic elution mode gave good column performance. Both flavonoid glycosides and terpene lactones were nearly completely eluted, their purities all met the standardized contents of G. biloba L. extracts (24 wt.% for flavonoid glycosides and 6 wt.% for terpene lactones), and their yields were nearly 100%. Finally, for a simulated two‐step elution mode (first step: 30% and second step: 70% ethanol), the product purity can be further improved, but at the expense of the product yield.