Gluconasturtiin or phenethyl glucosinolate is one of the most widely distributed

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 damaged. ...

s in the

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 ...

, mainly in the roots, and is probably one of the plant compounds responsible for the natural pest-inhibiting properties of growing crucifers, such as cabbage, mustard or rape, in rotation with other crops. This effect of gluconasturtiin is due to its degradation by the plant enzyme myrosinase into

phenethyl isothiocyanate Phenethyl isothiocyanate (PEITC) is a naturally occurring isothiocyanate whose precursor, gluconasturtiin is found in some cruciferous vegetables, especially watercress. PEITC has been studied for its potential for chemoprevention of cancers, ...

, which is toxic to many organisms. Gluconasturtiin is named from its occurrence in

watercress Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family, Brassicaceae. Watercress is a rapidly growing perennial plant native to Eurasia. It is one of the oldest known leaf vegetabl ...

(''Nasturtium officinale''). Among the vegetables, it is also found in

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 ...

(''Armoracia rusticana'') along with

sinigrin Sinigrin or allyl glucosinolate 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 sinigri ...

. Both compounds elicit a

pungent 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 ...

taste.

Occurrence

The compound was first reported in 1899, after its isolation from watercress, ''

Nasturtium officinale Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family, Brassicaceae. Watercress is a rapidly growing perennial plant native to Eurasia. It is one of the oldest known leaf vegetab ...

'', and the cress ''

Barbarea verna ''Barbarea verna'' is a biennial herb in the family Brassicaceae. Common names include land cress, American cress, bank cress, black wood cress, Belle Isle cress, Bermuda cress, poor man's cabbage, early yellowrocket, early wintercress, scurvy ...

''. Gluconasturtiin is now known to occur widely in other brassica families including

Brassicaceae Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...

and

Resedaceae Resedaceae is a family of mostly herbaceous dicotyledonous plants comprising 107 known species in 8 to 12 genera. 11 genera are currently accepted:

. In one investigation of horseradish roots, sinigrin represented 83% and gluconasturtiin 11% of the extracted glucosinolates.

Synthesis

Biosynthesis

Gluconasturtiin is biosynthesised from the amino acid

phenylalanine Phenylalanine (symbol Phe or F) is an essential α-amino acid with the chemical formula, formula . It can be viewed as a benzyl group substituent, substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of ...

in a multi-step pathway.

Laboratory synthesis

The first laboratory synthesis served to confirm the compound's structure. Later work allowed many glucosinolates including this phenethyl derivative to be made. These processes are more efficient than isolating pure materials from the plants in which they are naturally found.

Function

The natural role of glucosinolates are as plant defense compounds. The enzyme myrosinase removes the glucose group in gluconasturiin to give an intermediate which spontaneously rearranges to

. This is a reactive material which is toxic to many insect predators and its production is triggered when the plant is damaged. This effect has been called the mustard oil bomb. At concentrations typically found in foods, the glucosinolates are not toxic to humans and can be useful flavor components.

References