Ingenious application of ethylenediaminetetraacetic acid disodium to improve the extraction yield of psoralen in fig (Ficus carica L.) leaves

In this study, ethylenediaminetetraacetic acid (EDTA) disodium was first chosen as catalyst to convert psoralenoside (PO) to psoralen (PSO) for increasing the extraction yield of PSO. An efficient continuous system for synchronous transformation and extraction of PSO from fig leaves applying microwave-assisted EDTA disodium (MAE-EDTA) was developed. The optimal MAE-EDTA condition was obtained: EDTA disodium concentration of 0.07 mol·L-1, ethanol volume fraction of 56%, extraction time of 16 min, and extraction temperature of 70 °C by single factor experiments and response surface method (RSM). Under the optimal condition, the yield of PSO reached 27.24 mg·g-1. Compared with microwave-assisted ethanol extraction (MAE) and reflux extraction (RE), the yield of PSO by MAE-EDTA is 2.03-fold higher than RE and 1.70-fold higher than MAE. Therefore, MAE-EDTA is an efficient method for extracting PSO from fig leaves, and it might provide references for the extraction of PSO from other medicinal plants.