Semicarbazide-Sensitive Amine Oxidase, also known as SSAO and AOC3 (Amine oxidase, copper containing 3), is an enzyme in humans that catalyzes the oxidative conversion of amines to aldehydes in the presence of copper and quinone as cofactors. It has adhesive properties and also has functional monoamine oxidase activity.
Like monoamine oxidase (MAO-A and MAO-B), SSAO can deaminate short-chain primary amines, but is insensitive to MAO inhibitors. Semicarbazide was one of the first compounds found to inhibit this enzyme.
Several psychoactive compounds are substrates of SSAO (mescaline, tyramine, phenethylamine, etc.). Often these compounds are also substrates of MAO-A and MAO-B enzymes (phenethylamine for example).
In humans, cell-associated SSAO is mainly expressed in smooth muscle cells of the vasculature (blood vessels), endothelial cells of lymphatic organs, liver sinusoidal tissue, brain microvasculature (small blood vessels in the brain), and adipocytes (fat cells).[5]
Substrates
- Aminoacetone
- Benzylamine
- Cadaverine
- Ethylamine
- Histamine
- Mescaline
- Methylamine
- Phenethylamine
- Putrescine (found in humans and in high amounts in orange and grapefruit juice)
- Pyrrolidine1
- Serotonin
- Tryptamine
- Tyramine
Inhibitors
Potent Inhibitors Inhibitors | Strength | Dosage | Verified in Man |
---|---|---|---|
Cranesbill (contains geraniin) | ? | ? | ? |
Geraniin | IC50=0.00658 mM | ? | ? |
Heptylamine | IC50=0.007 mM | ? | ? |
Hexylamine | IC50=0.06 mM | ? | ? |
Nonylamine | IC50=0.000002 mM | ? | ? |
Octylamine | IC50=0.002 mM | ? | ? |
Phenylhydrazine | IC50=0.00003 mM | ? | ? |
Weak Inhibitors | Strength | Dosage | Verified in Man |
Butylamine | IC50=0.1 mM | ? | ? |
Caffeine | IC50=0.8 ± 0.3 mM[1] [4] | ? | ? |
Coffee (contains caffeine) | ? | ? | ? |
Methylamine | IC50=1 mM | ? | ? |
Penthylamine | IC50=0.1 mM | ? | ? |
Phenethylamine | IC50=0.3 mM | ? | ? |
Tryptamine | IC50=0.3 mM | ? | ? |
Inhibitors (Unknown Potency) | Strength | Dosage | Verified in Man |
Aminoguanidine [2] | ? | ? | ? |
B-24 [2] | ? | ? | ? |
Benserazide [2] | ? | ? | ? |
Carbidopa [2] | ? | ? | ? |
FLA 336 [2] | ? | ? | ? |
Galactosamine [3] | ? | ? | ? |
Glucosamine [3] | ? | ? | ? |
Hydralazine [2] | ? | ? | ? |
Hydroxylamine [2] | ? | ? | ? |
Iproniazid [2] | ? | ? | ? |
MDL-72145 [2] | ? | ? | ? |
MDL-72974A [2] | ? | ? | ? |
Mannosamine [3] | ? | ? | ? |
(+)Mexiletine [2] | ? | ? | ? |
Phenelzine [2] | ? | ? | ? |
Phyllanthus urinaria L (contains geraniin) | ? | ? | ? |
Procarbazine [2] | ? | ? | ? |
Propargylamine [2] | ? | ? | ? |
Pyridoxamine [2] | ? | ? | ? |
Semicarbazide [2] | ? | ? | ? |
1-(isoquinolin-1-ylcarbonyl)pyrrolidine-2-carboxamide [6] | ? | ? | ? |