Biosynthesis of the Belladonna Alkaloids

Abstract

A NUMBER of independent investigators have examined the distribution of alkaloids in the tissues of Atropa^1,2,3 and Datura^1,2,4,5 seeds. They have used a variety of precipitants ; but principally iodine in potassium iodide, which, with the technique developed by Errera⁶ and his school, is the most dependable for revealing the whereabouts of alkaloids by precipitation within tissues. These workers are agreed that the belladonna and thorn-apple alkaloids are restricted in the ripe seed to the peripheral layers, that is, to the testa itself and especially to a thin layer of cells lying between the testa and the endosperm ; probably a perisperm derived from the nucellus. This curious distribution is also found in the seeds of Hyoscyamus^1,4. It has been confirmed in my own laboratory for those of belladonna³. Barth⁵, examining Datura stramonium seeds that were not quite ripe, thought that there might be a little alkaloid also in the embryo and endosperm. Other investigators examining seeds that were fully ripe found none in either of these parts.