Determination of digitoxigenin glycosides in "Moroheiya" (Corchorus olitorius) and its products by HPLC

Seeds of "Moroheiya" (C. olitorius) contain not only strophanthidin (SP) gl ycosides, but also digitoxigenin (DG) glycosides. In an earlier paper(11)), we reported that SP glycosides were not detected in fresh "Moroheiya" (inc luding green leaf, green stem, shoot and pod), which is ingested in Japan a s a vegetable, in dried health tea products and in health food products. In this report we deal with analysis of DG glycosides in them. Methanol extracts of edible samples were hydrolyzed in methanol-0.3 mol/L H Cl (2 : 1) for 6 days at room temperature. A solution of the hydrolysate in a mixture of hexane-ethyl acetate (1:1) (2 mt) was applied to a Bond Elut Silica cartridge. The eluate by 10 mt of the solvent mixture was concentrat ed to dryness and the residue was redissolved in methanol (1 mt). Then, 10 mu L of the solution was subjected to HPLC to determine DG at UV 220 nm. Well-matured seeds and their pods contained DG glycosides at a concentratio n of 200 and 4 mu g/g, respectively, as DG. However, DG glycosides, as well as SP glycosides, were not detected in the edible samples.