Dioscorine isolation

Piperidine Alkaloids.—The hypothesis that dioscorine (112) was derived from six acetate units has been tested by administration of sodium [l- " C]acetate to Dioscorea hispida. Degradation of the dioscorine isolated showed, significantly, that of the carbons of the isoquinuclidine ring only C-5 was heavily labelled (30% of total). The remaining activity was located equally at C-10 and C-12. Thus dioscorine is built of only four acetate units, the remaining carbons of the skeleton being derived probably from lysine via a piperidine moiety such as A -piperideine (Scheme 10). 

The work in this branch of alkaloid chemistry has been extensive and, although a number of these bicyclic hydramines have been isolated, it must be emphasized that all possible combinations of I have not as yet been found in nature. Dioscorine, although it does fulfill the requirements of the above generalized formula, is a lactone ... 

Dioscorine, C13H19O2N (188, 248), has been isolated from the tubers ( gadoeng ) of Dioscorea hirsuta Blume (241) and from the same organ ( nami ) of Dioscorea hispida Dennst. which are indigenous to Batavia and the Tagalog provinces of the Philippines. Gadoeng and nami are used by the natives as a foodstuff after removal of the poisonous principle. 

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