Studies on the synthesis of hyoscyamine in Atropa belladonna L. and Datura stramonium L

Abstract

In previous papers [Cromwell, 1933, 1937], experiments on the biosynthesis of the alkaloids berberine and hyoseyamine in Berberi8 darwvini and Atropa belladonna respectively led to the conclusion that these alkaloids are synthesized from products of carbohydrate and protein breakdown. This work has been continued with the object of throwing further light on the nature of the intermediate reactions leading to the formation of hyoscyamine in Atropa belladonna and Datura 8tramonium. METHODS Material. Plants of Atropa belladonna and Datura stra-monium were raised from seed and set out in plots or grown in pots. Preparation of material for estimation of total alkaloid. Leaves were rapidly dried at a temperature of 600 in an oven and ground to fine powder. Samples of root j in. in diameter were detached from the crowns in the case of Atropa, washed thoroughly, cut into pieces and dried at 600. Roots of Datura were also washed, and dried at 600. When completely dry, the roots were ground to fine powder. Estimation of total alkaloid8. Leaf or-root powder (5-10 g.) was exhaustively extracted with dry ethanol in a Soxhlet extractor. The extract was transferred to an evaporating basin and the ethanol removed on a water-bath at 60-700. The resinous residue was extracted with 50 ml. 0-5N H2S04 and subsequently washed twice with 25 nml. portions of acid. The combined extracts and washings were next shaken with 100 mL of a mixture of 4 vol. of ether and 1 vol. of chloroform, to remove impurities. The acid extract was made alkaline with dilute ammonia and the bases shaken out with three 100 ml. portions of the ether-chloroform mixture. The three extracts were combined and the solvent distilled off. The residue was treated with two portions of 10 ml. ether which were completely removed by evaporation at 800. Volatile bases and free ammonia were driven off by heating on the water-bath at 1000 for 15 min. The residue was dissolved in 25 ml. N/50 H2SO4 and the excess titrated with N/50 NaOH with methyl red as indicator, and the results calculated in terms of' hyoscyamine. (1 ml. of N/50 acid_0-005784 g. hyos-cyamine.) Recovery of hyoseyamine as picrate gave proof that this base is chiefly responsible for the titration values obtained. The theoretical amount of aqueous picric acid was added to the alkaloid solution after neutralization, and the crystals (plates) purified by recrystallizing twice from water. The picrate obtained had m.p. 163-164°. (Found: N, 10*89 %. Calc. for hyoscyamine picrate, N, 10-81%.) Pure hyoscyamine picrate has m.p. 165°. Biochem. 1943, 37 The results obtained from four plants donna are given in the following table: Wt. of powder (g.) (1) 5 (leaf) 5 (root)