Special Effect of Ionic Liquids on Extraction of Diosgenin from Fenugreek (Trigonella foenum-graecum L.) by Ultrasonic Assistance

Abstract

An Ionic Liquid Based Ultrasonic Assisted Extraction (ILUAE) was developed for profitable extraction of diosgenin from fenugreek leaves. Imidazolium based ionic liquids (ILs) differing in their anions was used as catalytic agent for extraction procedure in order to optimize the diosgenin extraction. Five ionic liquids, concentration of ILs, reaction time and solid to liquid ratio were optimized on one at the time procedure. The particle size was considered the same for all experiments [BMIM]HSO4 was selected as the best IL and in the final optimized condition, the extraction efficiency increased from 0.77 to 10.24 (mg g-1dw) diosgenin. The method was also used to evaluate the concentration of diosgenin in different 13 accessions of Iranian fenugreek cultivated in the same place. The highest concentration of diosgenin with 20.2 and 20.1 (mg g-1dw) were found in the Khash and Qaen accessions, respectively. Accession of Mashhad showed the lowest concentration with 6.8 (mg g-1dw) diosgenin. After the reaction, the ILs from the media was also recovered using SPE column with more than 75% of yield. The result of this study showed that the optimized condition could extract the diosgenin almost five times more than the conventional method which could introduce fenugreek especially the best accession, as a new potential crop and source of diosgenin in the pharmaceutical industry