Atropine, a tropane alkaloid, is a free base of its sulfate [
A0550] which was first extracted from the root of belladonna (
Atropa belladonna) in 1830s. Atropine is a enantiomeric mixture of (
R,
S)-hyoscyamine (
dl-hyoscyamine), racemization occurring during the extraction procedure, whereas only (
S)-hyoscyamine (
l-hyoscyamine) [
H0450] is the active isomer. Atropine is a competitive antagonist of muscarine-like actions of acetylcholine and is therefore classified as an antimuscarinic agent. Atropine does not distinguish among the M
1, M
2, and M
3 subgroups of muscarinic receptors. Atropine inhibits the action of acetylcholine at postganglionic nerve endings, thus affecting receptors of the exocrine glands, smooth muscle, cardiac muscle and the central nervous system. (The product is for research purpose only.)