Research Items

Abstract

Putrescine in the Biosynthesis of Hyoscyamine IN plants of Atropa belladonna and Datura stramonium, growing normally, hyoscyamine appears to be formed principally in the root, with putrescine as an intermediate metabolite, and then moves upwards through the vessels into the stem, leaves, fruit and seeds (B. T. Cromwell, Biochem. J., 37, 717 and 722; 1943). The author's previous work on the biosynthesis of berberine and hyoscyamine had led to the conclusion that these alkaloids are synthesized from products of carbohydrate and protein breakdown. Work on the nature of the intermediate reactions leading to the formation of hyoscyamine, by experiments on exudates of cut stems, grafting and slow injections of various substances into stem stumps or branches of Atropa belladonna and Datura stramonium, showed the root as the probable locus of synthesis, and demonstrated the stimulating effect of arginine, hexamine, formamol and especially putrescine. This is compared with results of other workers (for example, Dawson, Science, 94, 396; 1941), who concluded that nicotine is synthesized mainly in the root of the tobacco plant and that the alkaloid moves from the root system via the xylem to the leaves. It was of interest to determine the manner in which putrescine provided its contribution to the hyoscyamine molecule. Bearing in mind the use of succinaldehyde in the synthesis of tropinone, it might be concluded that putrescine gives rise to succinaldehyde by oxidation. The occurrence of an enzyme system bringing about the oxidative deamination of putrescine with formation of ammonia and an aldehyde in roots and etiolated shoots, and the isolation of small amounts of putrescine from leaves and upper stems of Atropa belladonna and Datura stramonium, add weight to these considerations.