Toxicity and Bitterness in Australian Dioscorea bulbifera L. and Dioscorea hispida Dennst. from Thailand

Abstract

Underground tubers of bitter yams (Dioscorea bulbifera L. commonly known as var. rotunda), which are eaten after complex processing by Australian aborigines, were analyzed for acute toxicity and for the toxic alkaloid dioscorine. Results demonstrated that these tubers were not toxic, so they were extracted and the extracts were analyzed by thin-layer chromatography in order to determine the cause of bitterness. A major bitter component was found to be diosbulbin D (0.07 mg/g), a furanoid norditerpene previously isolated by Ida et al. (1978). Traditional aboriginal food processing techniques were found to be very efficient in removing diosbulbin D, thus making the bitter yams palatable. The alkaloid and bitter principle content of raw samples of this variety was compared with that of a dioscorine-containing yam from Thailand (Dioscorea hispida Dennst.), which is also used as food. © 1984, American Chemical Society. All rights reserved.