Phenethyl Isothiocyanate PEITC.

Gluconasturtiin is the glucosinolate that myrosinase hydrolyses to release phenethyl isothiocyanate. It is the direct precursor and the reason watercress preparations carry PEITC activity.

Isothiocyanates only appear once a glucosinolate is cleaved by plant myrosinase or by gut bacterial thioglucosidase. A glucosinolate extract supplies the upstream reservoir that PEITC is generated from.

Both isothiocyanates modify reactive cysteines on KEAP1 and release Nrf2 to drive phase II enzyme transcription. Their side chains differ, so tissue distribution and half-life differ while the receptor step is shared.

AITC comes from sinigrin and shares the electrophilic isothiocyanate group that acts on KEAP1 cysteines and on TRPA1 channels. Combined cruciferous preparations carry the two together naturally.

Broccoli sprout preparations supply both glucoraphanin and, when unheated, active myrosinase. That enzyme also cleaves gluconasturtiin, so the extract can raise conversion of the PEITC precursor.

DIM arises from indole-3-carbinol, the other main branch of glucosinolate breakdown, and acts largely through the aryl hydrocarbon receptor rather than KEAP1. The pair covers both cruciferous branches.

Isothiocyanates react rapidly with free thiols, and the N-acetylcysteine conjugate is the main urinary form PEITC leaves the body as. A large co-dosed NAC load caps the electrophile before it reaches KEAP1, which works against the intended action.

Glutathione S-transferase conjugates PEITC with glutathione as the first step of the mercapturic acid pathway. Supplying extra glutathione at the same time increases conjugation and shortens the free isothiocyanate's working life.

Isothiocyanates raise transcription of phase II and thioredoxin reductase genes, and thioredoxin reductase and glutathione peroxidase are selenoenzymes that need selenium at their active site. Induction without the trace element leaves the enzyme unfinished.

PEITC conjugates with glutathione, then moves stepwise to the cysteine and finally the N-acetylcysteine conjugate excreted in urine as a dithiocarbamate. Cysteine supply sets the ceiling on glutathione synthesis, which makes it part of the clearance route rather than an added benefit. In vitro work indicates the N-acetylated conjugate is not simply an inert end product.

Glutathione is assembled from glutamate, cysteine and glycine, and that tripeptide is what PEITC is conjugated to on its way out. Glycine is rarely the limiting member. It is named because the pathway does not run without it.

Glutamine is converted to glutamate, which glutamate-cysteine ligase joins to cysteine as the committed step of glutathione synthesis. Higher conjugation demand draws on that pool. Straight biochemistry, with no effect size implied.

Thiocyanate, one of the products of glucosinolate hydrolysis, competes with iodide at the transporter that concentrates iodide into thyroid tissue. The systematic review found the evidence that ordinary brassica intake shifts thyroid function measures to be limited, and it is a review of mixed human and animal studies rather than a trial. The competition itself is established transport pharmacology, which is why adequate iodine intake belongs in the picture at high glucosinolate doses.

Watercress that has been cooked or an extract that has been heat processed delivers intact gluconasturtiin, which human enzymes cannot cleave. Colonic bacteria supply that step, and the wide between-person variation in urinary dithiocarbamate recovery after a fixed glucosinolate dose is the visible consequence. Whether a specific supplemented strain adds hydrolytic capacity has not been measured here.

Fermentable fibre changes the composition and metabolic activity of the colonic community that performs glucosinolate hydrolysis. The step from that shift to more PEITC in blood is inferred rather than measured. Read it as an upstream lever, not a demonstrated gain.

Free PEITC is an oily, pungent, water-reactive liquid, which is why supplemental material is carried in a lipid or encapsulated. Lipid carriage limits volatilisation and hydrolysis during storage as well as supporting micellar uptake. The stability benefit is clear; the absorption gain in people has not been quantified in this record.

Both compounds modify reactive cysteine thiols on Keap1, which releases Nrf2 to raise transcription of conjugating enzymes. Because they act on the same sensor, the effects can overlap rather than add cleanly. What is measured in cell work is gene expression, a marker rather than an outcome.

Curcuminoids and PEITC both act as electrophilic inducers of the antioxidant response element, raising expression of glutathione S-transferases and NQO1 in cultured cells. The review that names PEITC in this role is a narrative synthesis, not a trial of the pair. Overlap at the same switch is the honest description.

EGCG and PEITC each raise phase II enzyme expression through the same transcriptional route in cultured cells. Both are also heavily conjugated on absorption, so they draw on overlapping clearance capacity. No human combination data sits behind this row.

Silymarin and PEITC both raise conjugating-enzyme expression in liver cells and rodent models. The PEITC liver work available here is in mice and reports damage markers, not human outcomes. Formulators pair them on that shared preclinical mechanism.

Watercress delivers ascorbate alongside gluconasturtiin as a matter of botany, and a narrative review of watercress composition covers both. In a formulation, ascorbate mainly affects pigment and isothiocyanate stability rather than acting on the same target. This is a matrix and stability relationship, not a demonstrated physiological pairing.

Tocopherol stops lipid radical chains directly inside membranes, while PEITC works indirectly by raising the cell's own conjugation and reduction capacity. The two mechanisms are distinct enough to be described as complementary. No combination measurement supports a size for that in people.

Resveratrol is described as an inducer of the same antioxidant-response genes PEITC acts on in cultured cells. Both are also cleared quickly by conjugation, which limits how much of either reaches tissue. The row is mechanistic overlap at low confidence.

PEITC is a small lipophilic organic molecule and falls squarely inside the adsorption range of activated charcoal. Taken together, less free PEITC remains available to cross the intestinal wall. Separating intake by several hours is the usual handling.