consciousness, as well as the deliriousness in particular are tied to the compound’s activity at the M1 muscarinic receptor. M1 receptors are located primarily in the central nervous system and are involved in perception, attention and cognitive functioning. Delirium is only associated with the antagonism of postsynaptic M1 receptors and currently other receptor subtypes have not been implicated. Peripheral muscarinic receptors are part of the autonomic nervous system. M2 receptors are located in the brain and heart, M3 receptors are in salivary glands and M4 receptors are in the brain and lungs. Due to the drug’s inhibition of various signal transduction pathways, the decrease in acetylcholine signaling is what leads to many of the cognitive deficits, mental impairments and delirium associated with psychoactive doses. Medicinal effects appear to mostly be tied to activation of the peripheral receptors and only from marginal decreases in acetylcholine signaling. Although often broadly referred to as simply being ‘anticholinergic’, antimuscarinic would be more specified and accurate terminology to use for scopolamine, as for instance it is not known to block nicotinic receptors. Biosynthesis in plants Scopolamine is among the secondary metabolites of plants from Solanaceae (nightshade) family of plants, such as henbane (Hyoscyamus niger), jimson weed (Datura), angel's trumpets (Brugmansia), deadly nightshade (Belladonna), mandrake (Mandragora officinarum), and corkwood (Duboisia). The biosynthesis of scopolamine begins with the decarboxylation of L-ornithine to putrescine by ornithine decarboxylase. Putrescine is methylated to N-methylputrescine by putrescine N-methyltransferase. A putrescine oxidase that specifically recognizes methylated putrescine catalyzes 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 enzymatic activity could be demonstrated to catalyze this reaction. Hygrine further rearranges to tropinone. Subsequently, tropinone reductase I converts tropinone to tropine, which condenses with phenylalanine-derived phenyllactate to littorine. A cytochrome P450 classified as Cyp80F1 oxidizes and rearranges littorine to hyoscyamine aldehyde. In the final step, hyoscyamine undergoes epoxidation catalyzed by 6beta-hydroxyhyoscyamine epoxidase yielding scopolamine. History Plants naturally containing scopolamine such as Atropa belladonna (deadly nightshade), Brugmansia (angels trumpet), Datura (Jimson weed), Hyoscyamus niger, Mandragora officinarum, Scopolia carniolica, Latua and Duboisia myoporoides have been known about and used for various purposes in both the New and Old Worlds since ancient times. Being one of the earlier alkaloids isolated from plant sources, scopolamine has been in use in its purified forms (such as various