Phenethylamines

Phenethylamine (&beta;-Phenylethylamine) is an alkaloid and monoamine. In the human brain, it is believed to function as a neuromodulator or neurotransmitter (trace amine). A colorless liquid that forms a solid carbonate salt with carbon dioxide (CO2) upon exposure to air, phenethylamine in nature is synthesized from the amino acid phenylalanine by enzymatic decarboxylation. It is also found in many foods, especially after microbial fermentation, e.g., in chocolate. It has been suggested that phenethylamine from food (e.g., chocolate) may have psychoactive effects in sufficient quantities. However, it is quickly metabolized by the enzyme MAO-B, preventing significant concentrations from reaching the brain.

Substituted phenethylamines are a broad and diverse class of compounds that include neurotransmitters, hormones, stimulants, hallucinogens, entactogens, anorectics, bronchodilators, and antidepressants.

The phenethylamine structure can also be found as part of more complex ring systems such as the ergoline system of LSD or the morphinan system of morphine.

Substituted phenethylamines


Substituted phenethylamines carry additional chemical modifications at the phenyl ring, the sidechain, or the amino group:


 * Amphetamines are homologues of phenethylamines carrying an alpha-methyl (&alpha;-CH3) group at the sidechain carbon atom next to the amino group.
 * Catecholamines are phenethylamines carrying two hydroxy groups in positions 3 and 4 of the phenyl ring. Examples are the hormones and neurotransmitters dopamine, epinephrine (adrenaline), and norepinephrine (noradrenaline).
 * The aromatic amino acids phenylalanine and tyrosine are phenethylamines carrying a carboxyl group (COOH) in alpha position.

Pharmacology
Many substituted phenethylamines are pharmacologically active drugs due to their similarity to the monoamine neurotransmitters:


 * Stimulants like the plant alkaloids ephedrine and cathinone and the synthetic drugs amphetamine (speed, benzedrine) and methylphenidate
 * Hallucinogens like the plant alkaloid mescaline and the synthetic drug 2C-B
 * Empathogen-entactogens like MDMA (ecstasy) and MDA
 * Anorectics like phentermine, fenfluramine, and amphetamine
 * Bronchodilators like salbutamol and ephedrine
 * Antidepressants like bupropion and the monoamine oxidase inhibitors phenelzine and tranylcypromine.

Substitution table
Some of the more important phenethylamines are tabulated below. For simplicity, the stereochemistry of the sidechain is not covered in the table. Hundreds of other simple synthetic phenethylamines are known. This is due in part to the pioneering work of Alexander Shulgin, much of which is described in the book PiHKAL.



Categorization
Fenylethylamin Phenethylamin Fenetilamina Phényléthylamine Fenyloetyloamina Fenetyyliamiiniphentermine Fenetylamin