Tag Archives: Gluconasturtiin


The Remarkable Anti-Cancer Benefits of Phenethyl isothiocyanate (PEITC)

Phenethyl isothiocyanate (PEITC) is one of a number of naturally occurring isothiocyanates.  In order to understand PEITC, you first have to start with their precursors, glucosinolates.

Glucosinolates constitute a natural class of organic compounds that contain sulfur and nitrogen and are derived from glucose and an amino acid.  For each glucosinolates there is a central carbon atom which is bound to a different side group.  The different side groups is what distinguishes each glucosinolate. Some of the more important and well researched glucosinolates include:

  • Glucotropaeolin
  • Gluconasturtiin
  • Glucoraphanin
  • Glucobrassicin
  • Glucocapparin
  • Progoitrin
  • Sinigrin
  • Sinalbin

Glucosinolates occur in various plants and vegetables including the families Brassicaceae (cruciferous vegetables).  Among the vegetables that contain glucosinolates are:

  • arugula
  • bok choy (pak choi)
  • broccoli
  • broccoli raab or rabe
  • broccoli sprouts
  • brussels sprouts
  • cabbages (savoy, red)
  • capers
  • cauliflower
  • cauliflower sprouts
  • Chinese cabbage
  • collards
  • daikon radish
  • garden cress
  • horseradish
  • kale
  • kohlrabi
  • maca root
  • mustard greens
  • mustard seeds
  • papaya seeds
  • radishes
  • turnip
  • wasabi japonica
  • watercress

The total number of documented glucosinolates from nature can be estimated to around 132, as of 2011.  1

Table 1. Glucosinolate Content of Selected Cruciferous Vegetables
Food (raw) Serving Total Glucosinolates (mg)
Brussels sprouts ½ cup (44 g)
Garden cress ½ cup (25 g)
Mustard greens ½ cup, chopped (28 g)
Turnip ½ cup, cubes (65 g)
Cabbage, savoy ½ cup, chopped (45 g)
Kale 1 cup, chopped (67 g)
Watercress 1 cup, chopped (34 g)
Kohlrabi ½ cup, chopped (67 g)
Cabbage, red ½ cup, chopped (45 g)
Broccoli ½ cup, chopped (44 g)
Horseradish 1 tablespoon (15 g)
Cauliflower ½ cup, chopped (50 g)
Bok choy (pak choi) ½ cup, chopped (35 g)

Source:  Linus Pauling Institute – Isothiocyanates

Isothiocyanates are biologically active hydrolysis (breakdown) products of glucosinolates.  Isothiocyanates are biologically inert and are only synthesized and formed by the conversion of the glucosinolate by the enzyme myrosinase.  Myrosinase coexists with but is physically separated from glucosinolates under normal conditions.

When vegetables that contain glucosinolates are chewed (plant tissue is damaged), myrosinase is released to convert the glucosinolate into a specific isothiocyanate.  In addition to myrosinase activity in the mouth saliva, the the intestinal microflora of both humans and animals also possess myrosinase activity.  2   

The enzyme myrosinase is activated by cutting or chewing the raw vegetables.  Heating of the vegetables (cooking) can destroy myrosinase activity.  3  Eating raw vegetables can releases 100% of the myrosinase enzyme and all of the isothiocyanates available, whereas cooking of the vegetables can reduce isothiocyanate content, depending on the method of cooking.  4 

This is why it is recommended that cruciferous vegetables be streamed or lightly boiled to preserve the glucosinolate content and not destroy all of the myrosinase enzymes.

Table 2. Food Sources of Selected Isothiocyanates and Their Glucosinolate Precursors
Isothiocyanate Glucosinolate (precursor) Food Sources
Allyl Isothiocyanate (AITC) Sinigrin Broccoli, Brussels sprouts, cabbage, horseradish, mustard, radish
Benzyl Isothiocyanate (BITC) Glucotropaeolin Cabbage, garden cress, Indian cress
Phenethyl-Isothiocyanate (PEITC) Gluconasturtiin Watercress
Sulforaphane (SFN) Glucoraphanin Broccoli, Brussels sprouts, cabbage

Source:  Linus Pauling Institute – Isothiocyanates

Each glucosinolate is a precursor to a different isothiocyanate.  There are four (4) different isothiocyanates that have been identified.  Each isothiocyanate has a specific glucosinolate precursor:

  • Sinigrin is the precursor to allyl isothiocyanate
  • Glucotropaeolin is the precursor to benzyl isothiocyanate
  • Gluconasturtiin is the precursor to phenethyl isothiocyanate
  • Glucoraphanin is the precursor to sulforaphane


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Figure 1:  Glucosinolates precursors to isothiocyanates  (Source:  Mechanisms of Action of Isothiocyanates in Cancer Chemoprevention: An Update)

Image result for glucosinolates myrosinase pathway

Figure 2:  Glucosinolates Hydrolysis by Myrosinase  (Source:  Linus Pauling Institute – Isothiocyanates)

Examples of vegetables with different glucosinolates are:

  • broccoli is a rich source of the glucosinolate glucoraphanin
  • cabbage is rich in sinigrin
  • watercress is high in gluconasturtiin


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Figure 3:  Examples of isothiocyanates in vegetables  (Source:  Mechanisms of Action of Isothiocyanates in Cancer Chemoprevention: An Update)

Isothiocyanates are known to science to have potent anticancer effects.  The research on these anticancer effects come from an analysis of the four isothiocyanates:
  • allyl isothiocyanate (AITC)
  • benzyl isothiocyanate (BITC)
  • phenethyl isothiocyanate (PEITC)
  • sulforaphane

Phenethyl isothiocyanate (PEITC) is one of the best studied members of the isothiocyanate family.  This is due to the fact that PEITC has generated a great deal of research interest due to its cancer chemopreventive activity.  5  6

PEITC is a naturally occurring isothiocyanate that is found in some cruciferous vegetables:

  • broccoli
  • horseradish (Armoracia rusticana)
  • radish
  • turnips
  • watercress

PEITC is present as the precursor gluconasturtiin in cruciferous plants. 

Watercress has the highest content of PEITC, due to the high levels of gluconasturtiin, which is actually named after watercress (Nasturtium officinale).


Figure 4:  Watercress

PEITC is known to not only prevent the initiation phase of carcinogenesis process but also to inhibit the progression of tumorigenesis. 7  PEITC targets multiple proteins to suppress various cancer-promoting mechanisms such as cell proliferation, progression and metastasis. PEITC (along with BITC) were the most effective isothiocyanates in inducing apoptosis.  8   PEITC has been shown to induce apoptosis in certain cancer cell lines, and, in some cases, is even able to induce apoptosis in cells that are resistant to some currently used chemotherapeutic drugs.  9

Another important benefit of PEITC is that it protects against DNA damage.  10   

PEITC’s other mechanism of action is proposed to involve inhibition of cytochrome P450 enzymes, which oxidize compounds such as benzo[a]pyrene and other polycyclic aromatic hydrocarbons (PAHs).

PEITC has been widely studied and shows great promise in inhibiting the proliferation of cancer cells and their ability to form tumors.  11

Following is a list of the molecular targets and major mechanism of action of PEITC in various cancer types:  12

Molecular targets and major mechanism of action of PEITC in various cancer types

Cancer typeReference(s)
Cholangio carcinoma7
Multiple Myeloma (MM)20
Myeloid leukemia21
Oral squamous carcinoma25


Informational References

Linus Pauling Institute – Isothiocyanates



Life Extension – Triple Action Cruciferous Vegetable Extract