Hyosamine

Hyosamine is a natural product belonging to the tropane alkaloids. It is a stereoisomer related to hyoscyamine and is found in several plants of the Solanaceae family, including Datura stramonium (jimsonweed), Hyoscyamus niger (henbane), and Atropa belladonna. In plant material, hyosamine commonly occurs alongside other tropane alkaloids such as hyoscyamine and scopolamine, with concentrations that vary by species, geographic origin, and growing conditions.

Chemically, hyosamine describes a chiral tropane ring system bearing a tertiary amine. It is related to the pharmacologically active atropine family and is often discussed as the levorotatory enantiomer associated with hyoscyamine. In practice, hyosamine is not widely used as a stand-alone therapeutic agent; pharmacological interest in the tropane alkaloids centers on hyoscyamine and scopolamine, while hyosamine is mostly considered in contexts such as natural product chemistry and biosynthesis.

Pharmacology and safety follow the broader tropane alkaloid profile. Tropane alkaloids act as muscarinic receptor antagonists and can produce anticholinergic effects, including dry mouth, blurred vision, tachycardia, urinary retention, confusion, and, at higher exposures, more serious toxicity. Therapeutic applications in modern medicine typically employ prescribed salts of hyoscyamine or related compounds rather than hyosamine alone.

Biosynthesis in plants proceeds through the general tropane alkaloid pathway, originating from amino-acid–derived precursors that form the core tropane skeleton and culminate in esters such as hyoscyamine; hyosamine is one of the stereoisomeric forms arising in this biosynthetic family.

See also: atropine, hyoscyamine, scopolamine.