Allyl isothiocyanate
Encyclopedia
Allyl isothiocyanate is the organosulfur compound with the formula CH2CHCH2NCS. This colorless oil is responsible for the pungent taste of mustard
, horseradish
, and wasabi
. This pungency and the lachrymatory effect of AITC is mediated through the TRPA1
and TRPV1
ion channels. It is slightly soluble in water, but well soluble in most organic solvents.
) or brown Indian mustard (Brassica juncea
). When these mustard seed
s are broken, the enzyme
myrosinase
is released and acts on a glucosinolate
known as sinigrin
to give allyl isothiocyanate.
Allyl isothiocyanate serves the plant as a defense against herbivore
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.
and potassium thiocyanate
:
The product obtained in this fashion is sometimes known as synthetic mustard oil. Allyl isothiocyanate can also be liberated by dry distillation
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 agent in foods. Synthetic allyl isothiocyanate is used as an insecticide
, bacteriocide, and nematocide, and is used in certain cases for crop protection.
Hydrolysis of allyl isothiocyanate gives allyl amine.
Mustard (condiment)
Mustard is a condiment made from the seeds of a mustard plant...
, horseradish
Horseradish
Horseradish is a perennial plant of the Brassicaceae family, which also includes mustard, wasabi, broccoli, and cabbages. The plant is probably native to south eastern Europe and the Arab World , but is popular around the world today...
, and wasabi
Wasabi
, also known as Japanese horseradish, is a member of the Brassicaceae family, which includes cabbages, horseradish, and mustard. Its root is used as a condiment and has an extremely strong flavor. Its hotness is more akin to that of a hot mustard rather than the capsaicin in a chili pepper,...
. This pungency and the lachrymatory effect of AITC is mediated through the TRPA1
TRPA1
Transient receptor potential cation channel, subfamily A, member 1, also known as TRPA1, is a protein which in humans is encoded by the TRPA1 gene....
and TRPV1
TRPV1
The transient receptor potential cation channel subfamily V member 1 ', also known as the capsaicin receptor and the vanilloid receptor 1, is a protein that, in humans, is encoded by the TRPV1 gene...
ion channels. It is slightly soluble in water, but well soluble in most organic solvents.
Biosynthesis and biological functions
Allyl isothiocyanate comes from the seeds of black mustard (Brassica nigraBrassica nigra
Brassica nigra is an annual weedy plant cultivated for its seeds, which are commonly used as a spice.-Description:...
) or brown Indian mustard (Brassica juncea
Brassica juncea
Brassica juncea, also known as mustard greens, Indian mustard, Chinese mustard, and leaf mustard, is a species of mustard plant. Subvarieties include southern giant curled mustard, which resembles a headless cabbage such as kale, but with a distinct horseradish-mustard flavor...
). When these mustard seed
Mustard seed
Mustard seeds are the small round seeds of various mustard plants. The seeds are usually about 1 or 2 mm in diameter. Mustard seeds may be colored from yellowish white to black. They are important spices in many regional foods. The seeds can come from three different plants: black mustard , brown...
s are broken, the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
myrosinase
Myrosinase
Myrosinase is a family of enzymes involved in plant defense against herbivores. Their structure has been elucidated and is available.-Myrosinase activity:...
is released and acts on a glucosinolate
Glucosinolate
The glucosinolates are a class of organic compounds that contain sulfur and nitrogen and are derived from glucose and an amino acid. They occur as secondary metabolites of almost all plants of the order Brassicales , but also in the genus Drypetes .-Chemistry:Glucosinolates are water-soluble...
known as sinigrin
Sinigrin
Sinigrin is a glucosinolate that belongs to the family of glucosides found in some plants of the Brassicaceae family such as Brussels sprouts, broccoli, and the seeds of black mustard to name but a few...
to give allyl isothiocyanate.
Allyl isothiocyanate serves the plant as a defense against herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
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.
Commercial and other applications
Allyl isothiocyanate is produced commercially by the reaction of allyl chlorideAllyl chloride
Allyl chloride is the organic compound with the formula CH2=CHCH2Cl. 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 chlorinated derivative of propylene.-Production:Allyl...
and potassium thiocyanate
Thiocyanate
Thiocyanate is the anion [SCN]−. It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called thiocyanates...
:
- 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
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
of the seeds. The product obtained in this fashion is known as volatile oil of mustard
Mustard oil
The term mustard oil is used for three different oils that are made from mustard seeds:*A fatty vegetable oil resulting from pressing the seeds,...
and is usually around 92% pure. It is used principally as a flavoring agent in foods. Synthetic allyl isothiocyanate is used as an insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
, bacteriocide, and nematocide, and is used in certain cases for crop protection.
Hydrolysis of allyl isothiocyanate gives allyl amine.
Safety
Allyl isothiocyanate is fairly toxic with LD50 of 151 mg/kg and is a dangerous lachrymator.See also
- PiperinePiperinePiperine is the alkaloid responsible for the pungency of black pepper and long pepper, along with chavicine . It has also been used in some forms of traditional medicine and as an insecticide. Piperine forms monoclinic needles, is slightly soluble in water and more so in alcohol, ether or...
, the active piquant chemical in black pepperBlack pepperBlack pepper is a flowering vine in the family Piperaceae, cultivated for its fruit, which is usually dried and used as a spice and seasoning. The fruit, known as a peppercorn when dried, is approximately in diameter, dark red when fully mature, and, like all drupes, contains a single seed... - CapsaicinCapsaicinCapsaicin 2CHCH=CH4CONHCH2C6H3-4--3- ) is the active component of chili peppers, which are plants belonging to the genus Capsicum. It is an irritant for mammals, including humans, and produces a sensation of burning in any tissue with which it comes into contact...
, the active piquant chemical in chili pepperChili pepperChili pepper is the fruit of plants from the genus Capsicum, members of the nightshade family, Solanaceae. The term in British English and in Australia, New Zealand, India, Malaysia and other Asian countries is just chilli without pepper.Chili peppers originated in the Americas...
s - Allicin, the active piquant flavor chemical in raw garlicGarlicAllium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...
- List of phytochemicals in food