Additional toxic, bitter saponins from the seeds of Chenopodium quinoa

Quinoa (Chenopodium quinoa) is an important Native American food grain. Prior to consumption, the seeds must be washed with H2O to remove bitterness and improve nutritive value. From the warm-H2O extract of quinoa seeds from Mexico, saponins 1-4 were isolated by monitoring the fractionation with brine shrimp lethality and a taste test for bitterness. By chemical, spectral, and enzymatic methods, 1-4 were identified as glycosides of oleanolic acid. Saponin 4, 3-O-[(beta-D-xylopyranosyl)(1----3)]-beta-D-glucuronopyranosyl-6-O -methyl ester]-oleanolic acid, is a new natural compound.