Ultrasound-assisted extraction of five isoflavones from Iris tectorum Maxim.

This study investigated the use of ultrasound-assisted extraction (UAE) to improve the extraction efficiency of the classical solvent extraction techniques such as maceration extraction (ME) and soxhlet extraction (SE) to extract five isoflavones (tectoridin, iristectorin B, iristectorin A, tectorigenin and iristectorigenin A) from Iris tectorum. The effects of various factors such as extraction solvent, solvent concentration, temperature, solvent to solid ratio, ultrasound power, extraction time and particle size on the yield of target components were investigated. The optimal UAE conditions found were: 70% (v/v) methanol solution, temperature 45 °C, solvent to solid ratio 15 ml/g, ultrasound power 150 W, extraction time 45 min and particle size 60-80 mesh. The results indicated that compared with ME at 18 h and SE at 6 h, UAE gave the highest extraction yields of tectoridin, iristectorin B, iristectorin A, tectorigenin, iristectorigenin A and total isoflavones at 45 min. The results indicated that UAE was an alternative method for extracting isoflavones from I. tectorum.