Ergothioneine is a naturally occurring, water-soluble amino acid of plant origin that accumulates in animal tissues. Dietary sources of ergothioneine include various types of mushrooms (king bolete, oyster mushroom), chicken liver, pork liver, pork kidney, oat bran, and beans (black turtle bean, red kidney bean).
Ergothioneine is a water-soluble thiol compound that is of interest to scientists and consumers for its potential beneficial effects as an antioxidant, which may protect against oxidative stress, as well as its anti-inflammatory, neuroprotective, and antiaging properties. Due to its potential benefits for the skin, it is found in some skin care products.
Ergothioneine cannot cross the plasma membrane of cells unless they express the ergothioneine transporter ETT (originally designated as OCTN1; human gene symbol SLC22A4). Ergothioneine specifically accumulates to millimolar concentrations in cell types that are normally subjected to high levels of oxidative stress (including erythrocytes and plasma). In humans, abnormal ETT and ergothioneine levels have been implicated in rheumatoid arthritis and Crohn's disease.
1-Carboxy-2-[2-mercaptoimidazole-4-(or 5)-yl]ethyl]-trimethyl-ammonium hydroxide, 2-mercaptohistidine trimethylbetaine, erythrothioneine, ET, ETT, L-Ergo, L-ergothioneine, OCTN1, S-alpha-carboxy-2,3-dihydro-N,N-N,-trimethyl-thioxo-1H-imidazole-4-eth-anaminium hydroxide, SLC22A4, sympectothion, thiasine, thiazine, thiolhistidinebetaine, thioneine, thiozine.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Limited evidence supports the use of a combination of hydroquinone and ergothioneine to treat hyperpigmentation. Further research is needed.