Allyl isothiocyanate (AITC) is a naturally occurring unsaturated

isothiocyanate In organic chemistry, isothiocyanate is a functional group as found in compounds with the formula . Isothiocyanates are the more common isomers of thiocyanates, which have the formula . Occurrence Many isothiocyanates from plants are produce ...

. The colorless oil is responsible for the pungent taste of

cruciferous vegetables Cruciferous vegetables are vegetables of the family Brassicaceae (also called Cruciferae) with many genera, species, and cultivars being raised for food production such as cauliflower, cabbage, kale, garden cress, bok choy, broccoli, Brusse ...

such as mustard, radish,

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

, and

wasabi Wasabi (Japanese language, Japanese: , , or , ) or Japanese horseradish (''Eutrema japonicum'' syn. ''Wasabia japonica'') is a plant of the family Brassicaceae, which also includes horseradish and Mustard plant, mustard in other genus, genera. ...

. This

pungency Pungency ( ) is 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 lower ...

and the lachrymatory effect of AITC are mediated through the

TRPA1 Transient receptor potential cation channel, subfamily A, member 1, also known as transient receptor potential ankyrin 1, TRPA1, or The Mustard and Wasabi Receptor, is a protein that in humans is encoded by the ''TRPA1'' (and in mice and rats by ...

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 ...

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 (''Rhamphospermum nigrum'') or brown Indian mustard (''Brassica juncea''). 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 An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

myrosinase is released and acts on a glucosinolate known as sinigrin to give allyl isothiocyanate. This serves the plant as a defense against

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

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

Production and applications

Allyl isothiocyanate is produced commercially by the reaction of allyl chloride 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. Uses Ch ...

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

distillation Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixt ...

of the seeds. The product obtained in this fashion is known as volatile oil of mustard. It is used principally as a

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

agent in foods. Synthetic allyl isothiocyanate is used as an

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

, as an anti-mold agent bacteriocide, and nematicide, 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.

Safety

Allyl isothiocyanate has an LD₅₀ of 151 mg/kg and is a lachrymator (similar to tear gas or mace).

Oncology

Based on ''

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

'' experiments and animal models, 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 Transient receptor potential channel modulators

Biosynthesis and biological functions

Production and applications

Safety

Oncology

See also

References