Allyl isothiocyanate (AITC) is an

organosulfur compound Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulf ...

(formula CH₂CHCH₂NCS). This colorless oil is responsible for the pungent taste of

mustard Mustard may refer to: Food and plants * Mustard (condiment), a paste or sauce made from mustard seeds used as a condiment * Mustard plant, one of several plants, having seeds that are used for the condiment ** Mustard seed, seeds of the mustard p ...

radish The radish (''Raphanus raphanistrum'' subsp. ''sativus'') is an edible root vegetable of the family Brassicaceae that was domesticated in Asia prior to Roman times. Radishes are grown and consumed throughout the world, being mostly eaten raw ...

horseradish Horseradish (''Armoracia rusticana'', syn. ''Cochlearia armoracia'') is a perennial plant of the family Brassicaceae (which also includes mustard, wasabi, broccoli, cabbage, and radish). It is a root vegetable, cultivated and used worldwi ...

, and

wasabi Wasabi ( Japanese: , , or , ; ''Eutrema japonicum'' or ''Wasabia japonica'') or Japanese horseradish is a plant of the family Brassicaceae, which also includes horseradish and mustard in other genera. The plant is native to Japan and the Russi ...

. This

pungency Pungency () refers to the taste of food commonly referred to as spiciness, hotness or heat, found in foods such as chili peppers. Highly pungent tastes may be experienced as unpleasant. The term piquancy () is sometimes applied to foods with a l ...

and the lachrymatory effect of AITC are mediated through the TRPA1 and

TRPV1 The transient receptor potential cation channel subfamily V member 1 (TrpV1), also known as the capsaicin receptor and the vanilloid receptor 1, is a protein that, in humans, is encoded by the ''TRPV1'' gene. It was the first isolated member of th ...

ion channels. It is slightly soluble in water, but more soluble in most organic solvents.

Biosynthesis and biological functions

Allyl isothiocyanate can be obtained from the seeds of black mustard (''

Brassica nigra ''Brassica nigra'', or black mustard, is an annual plant cultivated for its dark-brown-to-black seeds, which are commonly used as a spice. It is native to tropical regions of North Africa, temperate regions of Europe, and parts of Asia. Desc ...

'') or brown Indian mustard (''

Brassica juncea ''Brassica juncea'', commonly brown mustard, Chinese mustard, Indian mustard, leaf mustard, Oriental mustard and vegetable mustard, is a species of mustard plant. Cultivar ''Brassica juncea'' cultivars can be divided into four major subgroup ...

''). When these

mustard seed Mustard seeds are the small round seeds of various mustard plants. The seeds are usually about in diameter and may be colored from yellowish white to black. They are an important spice in many regional foods and may come from one of three diff ...

s are broken, the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

myrosinase Myrosinase (, ''thioglucoside glucohydrolase'', ''sinigrinase'', and ''sinigrase'') is a family of enzymes involved in plant defense against herbivores, specifically the mustard oil bomb. The three-dimensional structure has been elucidated and is ...

is released and acts on a

glucosinolate Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise damage ...

known as

sinigrin Sinigrin is a glucosinolate that belongs to the family of glucosides found in some plants of the family Brassicaceae such as Brussels sprouts, broccoli, and the seeds of black mustard (''Brassica nigra''). Whenever sinigrin-containing plant tis ...

to give allyl isothiocyanate. Allyl isothiocyanate serves the plant as a defense against

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

s; since it is harmful to the plant itself , it is stored in the harmless form of the glucosinolate, separate from the myrosinase enzyme. When an animal chews the plant, the allyl isothiocyanate is released, repelling the animal. Human appreciation of the pungent is learnt, perhaps wrongly for some, as all condiments above mentioned are

nephrotoxic Nephrotoxicity is toxicity in the kidneys. It is a poisonous effect of some substances, both toxic chemicals and medications, on kidney function. There are various forms, and some drugs may affect kidney function in more than one way. Nephrotoxins ...

. This compound has recently been shown to strongly repel fire ants, ('' Solenopsis invicta''). AITC vapor is also used as an antimicrobial and shelf life extender in food packaging.

Commercial and other applications

Allyl isothiocyanate is produced commercially by the reaction of

allyl chloride Allyl chloride is the organic compound with the formula C H2=CHCH2 Cl. This colorless liquid is insoluble in water but soluble in common organic solvents. It is mainly converted to epichlorohydrin, used in the production of plastics. It is a chl ...

and

potassium thiocyanate Potassium thiocyanate is the chemical compound with the molecular formula KSCN. It is an important salt of the thiocyanate anion, one of the pseudohalides. The compound has a low melting point relative to most other inorganic salts. Use in che ...

: :CH₂=CHCH₂Cl + KSCN → CH₂=CHCH₂NCS + KCl The product obtained in this fashion is sometimes known as ''synthetic mustard oil''. Allyl isothiocyanate can also be liberated by dry

distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the he ...

of the seeds. The product obtained in this fashion is known as volatile oil of mustard and is usually around 92% pure. It is used principally as a

flavoring A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the g ...

agent in foods. Synthetic allyl isothiocyanate is used as an

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed t ...

, as an anti-mold agent

bacteriocide A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on their ...

, and

nematicide A nematicide is a type of chemical pesticide used to kill plant-parasitic nematodes. Nematicides have tended to be broad-spectrum toxicants possessing high volatility or other properties promoting migration through the soil. Aldicarb (Temik), a ca ...

, and is used in certain cases for crop protection. It is also used in fire alarms for the deaf. Hydrolysis of allyl isothiocyanate gives

allylamine Allylamine is an organic compound with the formula C3H5NH2. This colorless liquid is the simplest stable unsaturated amine. Production and reactions All three allylamines, mono-, di-, and triallylamine, are produced by the treating allyl chlor ...

Safety

Allyl isothiocyanate has an LD₅₀ of 151 mg/kg and is a

lachrymator Tear gas, also known as a lachrymator agent or lachrymator (), sometimes colloquially known as "mace" after the early commercial aerosol, is a chemical weapon that stimulates the nerves of the lacrimal gland in the eye to produce tears. In ad ...

(similar to tear gas or mace).

Oncology

Based on ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology a ...

'' experiments and

animal model An animal model (short for animal disease model) is a living, non-human, often genetic-engineered animal used during the research and investigation of human disease, for the purpose of better understanding the disease process without the risk of ha ...

s, allyl isothiocyanate exhibits many of the desirable attributes of a cancer chemopreventive agent.

References

{{Xenobiotic-sensing receptor modulators Antibiotics Insecticides Isothiocyanates Pungent flavors Nematicides Allyl compounds Lachrymatory agents

Biosynthesis and biological functions

Commercial and other applications

Safety

Oncology

See also

References