Methyllycaconitine

Methyllycaconitine (MLA) is a diterpenoid alkaloid found in the Aconitum genus, particularly in the species Aconitum lycoctonum (wolf's bane). It is a potent neurotoxin, acting as a nicotinic acetylcholine receptor antagonist.

Chemistry

Methyllycaconitine is a diterpenoid alkaloid, a class of compounds derived from terpenes. It is structurally related to other Aconitum alkaloids such as aconitine and lycaconitine. The molecule consists of a cyclopentane ring fused to a cyclohexane ring, with a six-membered lactone ring and a seven-membered lactam ring.

Biosynthesis

The biosynthesis of methyllycaconitine in Aconitum lycoctonum involves the acylation of the diterpene geranylgeranyl pyrophosphate (GGPP) by an acyltransferase enzyme, followed by cyclization and oxidation reactions.

Pharmacology

Methyllycaconitine acts as a potent antagonist at nicotinic acetylcholine receptors, particularly the α7 subtype. It binds to the receptor's agonist binding site, preventing the binding of acetylcholine and thus inhibiting the receptor's function. This leads to symptoms of neurotoxicity, including muscle weakness, paralysis, and potentially respiratory failure.

Toxicology

Due to its potent neurotoxic effects, ingestion of methyllycaconitine can be fatal. It is one of the main toxic components of Aconitum lycoctonum, a plant that has been used historically as a poison. Symptoms of poisoning include nausea, vomiting, abdominal pain, and severe neurological effects such as seizures and loss of consciousness.

See also

• Aconitum
• Nicotinic acetylcholine receptor
• Neurotoxin