Microdetermination of diosgenin from fenugreek (Trigonella foenum-graecum) seeds.
Sulfuric acid hydrolysis of steroidal glycosides of Amber fenugreek was studied by capillary gas chromatographic analysis of diosgenin [(25R)-spirost-5-en-3-ol] and isomeric spirostadiene artifacts from 100 mg samples of seed material. Following extraction with 80% ethanol, highest recoveries of diosgenin occurred when hydrolyses were conducted in sulfuric acid, prepared at 1 molar (M) concentration in water containing 60-80% 2-propanol. Compared to a previous method with aqueous hydrochloric acid, the selected conditions of hydrolysis at 100 degrees C for 2 h with sulfuric acid in 70% 2-propanol reduced diene formation but did not completely eliminate these artifacts. Extraction of steroidal saponins with various alcohol/water mixtures prior to sulfuric acid hydrolysis gave similar recoveries of diosgenin. Application of the quantitative method to experimental samples of Amber, Quatro, and ZT-5 fenugreek, using 10 mg subsamples of crushed seed that had been defatted with petroleum ether and dried at 60 degrees C, gave diosgenin levels of 0.55, 0.42, and 0.75%, respectively. Levels of smilagenin and sarsasapogenin were very low in hydrolyzed seed extracts from ZT-5, a Canadian breeder line of fenugreek.
Taylor
W G
WG
Agriculture and Agri-Food Canada Research Centre, 107 Science Place, Saskatoon, Saskatchewan, Canada S7N 0X2. taylorw@em.agr.ca
Elder
J L
JL
Chang
P R
PR
Richards
K W
KW
D002849:Chromatography, Gas / Q000379:methods; D004144:Diosgenin / Q000032:analysis*; D008832:Microchemistry / Q000379:methods; D010936:Plant Extracts / Q000032:analysis*; D010946:Plants, Medicinal / Q000737:chemistry; D012639:Seeds / Q000737:chemistry*; D029910:Trigonella
D010936:Plant Extracts; C056164:fenugreek seed meal; D004144:Diosgenin