Anabaseine

Anabaseine (3,4,5,6-Tetrahydro-2,3’-bipyridine) is an alkaloid toxin produced by Nemertines and Aphaenogaster ants. It is structurally similar to nicotine and anabasine. Similarly, it has been shown to act as an agonist on most nicotinic acetylcholine receptors in the central nervous system and peripheral nervous system.

Mechanism of action

The iminium form of anabaseine binds to most nicotinic acetylcholine receptors in both the peripheral nervous system and central nervous system. But, there is a higher binding affinity for receptors in the brain with a α7 subunit, as well as skeletal muscle receptors. Binding causes the depolarization of neurons, and induces the release of release of both dopamine and norepinephrine.

Biological effects

Anabaseine causes paralysis in crustaceans and insects, but not in vertebrates, presumably by acting as an agonist on peripheral neuromuscular nicotinic acetylcholine receptors.

Structure

The anabaseine molecule consists of a non-aromatic tetrahydropyridine ring connected to the 3rd carbon of a 3-pyridyl ring. It can exist in three forms at physiological pH: a ketone, imine, or iminium structure. Due to conjugation between the imine and 3-pyridyl ring, anabaseine exists as a nearly coplanar molecule.