The Separation and Identification of Solanaceous Alkaloids From Normal and Grafted Plants

Abstract

For many years experimental grafting of alkaloid-forming plants on non-alkaloid-bearing stocks and vice versa has been carried out in several laboratories (Hieke, 1942;Dawson, 1942Dawson, , 1944James, 1944James, , 1945Cromwell, 1943), and considerable evidence has accumulated to suggest that the main seat of alkaloid synthesis in the plants normally forming mydriatic alkaloids is in their root systems (Dawson, 1948). In every case this work involved the grafting of a member to whom mydriatic alkaloids are foreign, and the results showed simply presence or absence of alkaloids. Recently, methods have been described by which the alkaloids hyoscyamine (including atropine) and hyoscine can be estimated separately in mixtures and so the ratio of the alkaloids in the plant can be determined. Trautner & Roberts (1948) described a method for the estimation of these alkaloids, a separation of the mixed bases being first achieved by adsorption chromatography, using activated silica, followed by titration. The method fails if the hyoscine proportion is less than 10% of the total; hence, while applicable to extracts from Duboisia species and many species of Datura (such as D. innoxia)*, it is unsuitable for extracts from Atropa belladonna. Evans & Partridge (1948) have more recently described a method using partition chromatography which can be used for extracts containing lower proportions of hyoscine. In the present investigation their work has been developed so that the method can be used to estimate these alkaloids in actual plant extracts; this made it possible to determine the hyoscine/hyoscyamine ratio in the plants, and it became clear that in Datura innoxia and Atropa belladonna, characteristic and very different ratios were normally developed. This suggested that reciprocal grafts of these two species in which both alkaloids are normally formed, but in very different proportions, might produce further and rather more elegant experimental evidence than was obtainable in the earlier work involving non-alkaloidal plants. A series of reciprocal grafts was made, therefore, and stock and scion dried and analysed separately as described below. METHODSThe grafts were all made as 'slip grafts'; a slip with terminal bud and two or three leaves was taken from a young, rapidly growing plant, the stem was trimmed to the shape of a narrow wedge and inserted in a slit made in a young stock plant. The slit was made below a leaf in the soft part of a growing stem. The whole was then bound tightly with raffia, and kept in a moist atmosphere. After 10 days or a fortnight the shoot of the stock • The name Datura innoxia is used in this paper for the plant commonly known as D. metel, as it appears from the work of Timmerman (1927) that the former name is correct.

Determination of Hyoscyamine and Scopolamine in Datura innoxia Plants by High Performance Liquid Chromatography

“…For the transformation of hyoscyamine into scopolamine different organs of the plant including the aerial parts have been discuss ed and the actual loci may vary with the different datura species [15][16][17][18][19][20][21][22][23][24][25]. The present data on alkaloid content and percentage of hyoscyamine in the differ ent root fractions of Datura innoxia (Table II) reveal that about 50% of the hyoscyamine were already transformed in the thin hairy roots.…”

THE DISTRIBUTION OF ACETYLCHOLINE IN THE MALAYAN JACK‐FRUIT PLANT, ARTOCARPUS INTEGRA

“…For locating the site of formation of other pharmacologically active substances in plants, a method of interspecific grafts involving members of different genera which have a different capacity for alkaloid production has been employed with some success by James (1953). For instance, James and Thewlis (1952) by studying grafts prepared from belladonna and Datura innoxia concluded that the root was the site of synthesis of the alkaloids hyoscine and hyoscyamine in these plants, and Evans and Partridge (1953) from a study of the distribution of alkaloids in grafts involving Datura tatula and D. feroxia found that the aerial parts of these plants were capable of synthesizing hysocyamine and meteloidine respectively. A similar method of approach could probably be employed for locating the site of formation of ACh in the Jack-fruit plant.…”

Alkaloids of the Genus Datura: Review of a Rich Resource for Natural Product Discovery

“…Although all parts of all Datura plants contain alkaloids, the roots are considered the primary site of alkaloid biosynthesis, and alkaloids are then trafficked throughout the plant. This was largely confirmed by the elegant grafting studies performed by James [53], where D. inoxia and A. belladonna roots and aerial parts (species which contain very different alkaloid profiles) were grafted onto each other. The resulting aerial tissues contained the alkaloid composition and ratio of the species used as the rootstock.…”

“…This procedure is limited to aromatic alkaloids and, therefore, under-quantifies total alkaloid content. Alkaloids have also been titrated with sulfuric acid and bromocresol green [ 52 ], or with sulfuric acid and then back-titrated with sodium hydroxide and methyl red [ 53 ]. The Mayer reagent (mercuric chloride and potassium iodide) forms a white precipitate upon reaction with alkaloids; it has even been used for preparative scale alkaloid isolation from D. stramonium [ 42 ].…”