Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is among the secondary metabolites of plants from Solanaceae (nightshade) family of plants, such as henbane, jimson weed and Angel's Trumpets (Datura or Brugmansia), and corkwood (Duboisia). Although scopolamine is sometimes portrayed in the media as a dangerous drug, its anticholinergic properties give it some legitimate medical applications in very minute doses. An example is the treatment of motion sickness by use of a transdermal patch.

Scopolamine is named after the plant genus Scopolia. The name "hyoscine" is from the scientific name for henbane, Hyoscyamus niger.

The biosynthesis of scopolamine begins with the decarboxylation of L-ornithine to putrescine by ornithine decarboxylase (EC 4.1.1.17). Putrescine is methylated to N-methylputrescine by putrescine N-methyltransferase (EC 2.1.1.53).

A putrescine oxidase (EC 1.4.3.10) that specifically recognizes methylated purtrescine catalizes the deamination of this compound to 4-methylaminobutanal which then undergoes a spontaneous ring formation to N-Methyl-pyrrolium cation. In the next step, the pyrrolium cation condenses with acetoacetic acid yielding hygrine. No enzmyatic activity could be demonstrated that catalyzes this reaction. Hygrine further rearranges to tropinone.