Phenethyl isothiocyanate / P21 Cancer Research Results

-PEITC bioavailability from fresh, chopped microgreens is high
-Co-consumption with other isothiocyanates is additive/synergistic
-Peak plasma levels: ~1–3 hours post-consumption
-Half-life: ~4–6 hours
-Generally well tolerated up to 40 mg/day (mild GI irritation at higher dose)

PEITC is best characterized for its dual role in xenobiotic metabolism:
Inhibition of Phase I enzymes
-Suppresses cytochrome P450 enzymes (e.g., CYP1A1, CYP2E1)
-Reduces activation of pro-carcinogens

-Selectively depletes GSH in cancer cells
-Directly increases ROS beyond buffering capacity

Key pathways in cancer cells
-GSH depletion
-Mitochondrial ROS amplification
-ASK1/JNK apoptosis

Chemo relevance
-Frequently chemo-sensitizing
-Opposite of NAC/GSH

Induction of Phase II enzymes
-Activates NRF2–KEAP1 signaling
-Increases expression of detoxification and antioxidant enzymes such as:
 -Glutathione S-transferases (GSTs)
 -NAD(P)H quinone oxidoreductase 1 (NQO1)
 -Heme oxygenase-1 (HMOX1)

In preclinical systems, PEITC has been shown to:
-Deplete intracellular glutathione (GSH), increasing oxidative stress in cancer cells
-Induce mitochondrial dysfunction and apoptosis
-Inhibit histone deacetylases (HDACs) (context-dependent)
-Suppress pro-survival signaling pathways (e.g., STAT3, NF-κB)
-Target cancer stem–like cells in some models

Dietary origins

PEITC present in vegetables such as:
-Watercress (the richest source)
-Broccoli
-Cabbage
-Brussels sprouts
-Radish

Bioavailability depends on:
-Food preparation
-Gut microbiota (myrosinase activity if plant enzyme is inactive)

watercress microgreens generally have higher PEITC (and/or its precursor gluconasturtiin) per gram than mature watercress.
-The enrichment is most pronounced per unit fresh weight in the 7–14 day window.
-Absolute values vary substantially with cultivar, light intensity, sulfur/nitrogen nutrition, and post-harvest handling.
| Growth stage    |      Age | PEITC potential (mg / 100 g FW) |         Relative |
| --------------- | -------: | ------------------------------: | ---------------: |
| **Microgreens** |   7–10 d |                     **3.0–6.0** | **~2–4×** mature |
| **Microgreens** |  11–14 d |                     **2.5–5.0** |            ~2–3× |
| Baby leaf       |  21–28 d |                         1.5–3.0 |            ~1–2× |
| Mature leaf     | 35–45+ d |                         0.8–1.5 |         baseline |

Dry weight basis
| Growth stage          | PEITC potential (mg / g DW) |
| --------------------- | --------------------------: |
| Microgreens (7–10 d)  |                 **1.8–3.5** |
| Microgreens (11–14 d) |                     1.5–3.0 |
| Mature leaf           |                     0.6–1.2 |

Expect 2–5× variability depending on:
-Light spectrum (blue light ↑ glucosinolates)
-Sulfur availability

Practical optimization tips
Lighting
-12–16 h/day
-150–300 µmol/m²/s PAR (typical shop LEDs at 20–30 cm distance)
Soil
-Peat or peat-blend preferred
-Avoid over-watering (dilutes concentration)
Nutrition (optional but effective)
-One light watering with ¼-strength sulfate-containing fertilizer around day 4–5 can increase PEITC ~15–30%
Harvest & use
-Cut, rest 5–10 minutes, then consume (allows myrosinase to fully convert gluconasturtiin → PEITC)

Dose: (100 g fresh microgreens ≈ 2–4 mg bioavailable PEITC)
-ie below doses are not really acheivable from fresh microgreens
Minimum biologically active dose (humans): ~10–15 mg PEITC/day
Common efficacy range used in human trials: 20–40 mg/day
Upper short-term doses studied (generally tolerated): 60 mg/day
Diet-achievable with watercress microgreens: Yes, at realistic portions
These doses are chemopreventive / pathway-modulating, not cytotoxic chemotherapy.
| PEITC dose (mg/day) | Dominant biological effects                     |
| ------------------: | ----------------------------------------------- |
|         **5–10 mg** | Phase II enzymes, mild NRF2                     |
|        **10–20 mg** | HDAC inhibition, ROS signaling                  |
|        **20–40 mg** | Apoptosis, cell-cycle arrest, anti-inflammatory |
|        **40–60 mg** | Strong redox stress in cancer cells             |
|              >60 mg | Limited data; GI irritation risk                |