Atroscine

Hyoscine (Scopolamine, Atroscine), Ci,H2i04N. The name hyoscine was first used by Hohn and Reichardt for the basie hydrolytic product of hyoscyamine, now known as tropine. It was subsequently used by Ladenburg for a supposed isomeridc of atropine, Cj HjgOjN, isolated from the mother liquors of hyoscyamine. This was found by Schmidt, Hesse and others to be identical with scopolamine, Ci,H2i04N, obtained by Schmidt from Scopolia japonica. The name hyoscine has priority and is in use, but scopolamine is also employed, especially in Germany. 

As noted from its formula (see Figure 14.2), scopolamine differs from atropine chemically in having an oxygen atom attached to the end carbon atoms of the scopine part of the molecule. Scopolamine is levorotatory but is readily racemized to the t/,/-form designated as atroscine. 

Scopolamine is levorotary to polarized light the racemic form, atroscine, which is often present in commercial scopolamine, acts only half as strongly on the peripheral organs, because in it the levorotary is mixed with the dextrorotary isomer, which is almost inactive. The cerebral action is equal, however, in the two forms. 

HytKcine is the older name for this alkaloid, though M opolamim is the accepted name in the United States. Scopolamine is the Uvo component of the racemie mixture that is known as atroscine. The alkaloid is racemized readily in the pre.sencc of dilute alkali. 

The carbon a to the carboxyl group of tropic add is asymmetric and is easily racemized during the isolation of the solanaceous alkaloids. Atropine and atroscine are racemic forms. The corresponding levo isomers, (-)-hyoscyamine and (-)-scopolamine(hyoscine), occur naturally in the solanaceous plants. 

Scopolamine (hyoscine) is isolated from the mother liquor remaining after the isolation of hyoscyamine, and is marketed as its hydrobromide. Scopolamine is readily race-mized to atroscine, when subjected to treatment with dilute alkali. 

These medicinal plants are now understood to owe their pharmacological and toxicological properties to several extremely potent alkaloids (Fig. 8-13). The first to be isolated in 1831 was atropine. Other solanaceous alkaloids are atroscine (which like atropine is racemic), hyoscyamine and scopolamine, and the levorotatory enantiomers of racemic atropine and atroscine, respectively. 

DL-Form, atroscine. Dihydrate, chisel-shaped prisms from ethanol + water, mp 38-40. Monohydrate, efflorescent crystals, mp 55-57. Anhydrous, long prisms, mp 82-83. Very slightly sol in water sol in ale, chloroform, ether, oils. 

S. occurs as the (-)-form (hyoscine) in several Solan-aceae genera [e. g. Atropa belladonna (deadly nightshade), Datura species (thorn apple), Duboisia species, Hyoscyamus species (henbane), Mandragora officinalis (mandrake), and Scopolia species (banewort)]. Racemic S. (atroscine) is a natural product of the Solanaceae Datura innoxia, Hyoscyamus niger, and Scopolia camiolica. S. is easily hydrolyzed in acidic and alkaline solution to tropic acid and scopine. 

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