Oleuropein (OLEU) — a secoiridoid polyphenol from olive leaf and olive fruit/extra-virgin olive oil; major in-vivo related phenolic is hydroxytyrosol (via hydrolysis/metabolism). Sources: olive leaf extract (standardized to oleuropein), EVOO phenolics.
Primary mechanisms (conceptual rank):
1) Redox modulation (ROS ↓ in normal tissue; stress/hormesis; NRF2 ↑ context-dependent)
2) Anti-inflammatory transcription suppression (NF-κB ↓)
3) Anti-proliferative signaling in cancer models (PI3K/AKT/mTOR ↓; MAPK modulation; apoptosis ↑; model-dependent)
4) Anti-angiogenic / hypoxia coupling (HIF-1α/VEGF ↓; model-dependent)
Bioavailability / PK relevance: Human data show absorption/metabolism after oral olive leaf extract; circulating forms are largely metabolites (and hydroxytyrosol-related), with limited free parent compound exposure. :contentReference[oaicite:0]{index=0}
In-vitro vs oral exposure: Many direct “anticancer” cytotoxic effects occur at micromolar concentrations that may exceed typical systemic exposure from supplements/foods (high concentration only for direct tumor cytotoxicity in many models). :contentReference[oaicite:1]{index=1}
Clinical evidence status: Nutraceutical/food bioactive with human data mainly for cardiometabolic/inflammation endpoints; oncology evidence largely preclinical/adjunct-hypothesis (no oncology approval).
Also available as a supplement usually labeled as Olive Leaf Extract. (20-50% concentrations)| Rank | Pathway / Axis | Cancer Cells | Normal Cells | TSF | Primary Effect | Notes / Interpretation |
|---|---|---|---|---|---|---|
| 1 | ROS | ↑ or ↓ (dose-/model-dependent) | ↓ (primary) | P/R | Redox reprogramming | Normal tissue: antioxidant/lipid-peroxidation reduction common. Cancer: higher exposures can induce stress/apoptosis; direction varies by model and co-stressors. |
| 2 | NF-κB / cytokine programs | ↓ | ↓ | R/G | Anti-inflammatory / anti-survival transcription | Commonly reported mechanism for oleuropein/olive phenolics. :contentReference[oaicite:3]{index=3} |
| 3 | NRF2 (protective vs resistance role) | ↔ / ↑ (context-dependent) | ↑ | R/G | Antioxidant gene induction | NRF2 modulation is frequently discussed for olive polyphenols; in cancer contexts can be double-edged (cytoprotection/resistance). :contentReference[oaicite:4]{index=4} |
| 4 | PI3K/AKT/mTOR | ↓ (model-dependent; high concentration only) | ↔ | R/G | Reduced anabolic survival signaling | Reported across cancer models and olive phenolic literature; translation depends on exposure. :contentReference[oaicite:5]{index=5} |
| 5 | Intrinsic apoptosis (Bax↑/Bcl-2↓; caspases) | ↑ (model-dependent; high concentration only) | ↔ | R/G | Mitochondrial apoptosis | Common downstream endpoint in preclinical cancer work; often coupled to redox and PI3K/AKT shifts. :contentReference[oaicite:6]{index=6} |
| 6 | HIF-1α / VEGF (angiogenesis) | ↓ (model-dependent) | ↔ | G | Reduced hypoxia-adaptation / vascular support | Typically secondary; varies strongly by model and readout. |
| 7 | Cell cycle checkpoints | ↓ proliferation (model-dependent) | ↔ | G | Cytostatic growth restraint | Often reported as G0/G1 or G2/M arrest in vitro; exposure gap is common. :contentReference[oaicite:7]{index=7} |
| 8 | Ferroptosis | ↔ (limited / context-dependent) | ↔ | R/G | Not canonical | Olive phenolics can influence lipid peroxidation, but a consistent oleuropein-driven ferroptosis program is not a core claim in the main reviews. |
| 9 | Ca²⁺ signaling | ↔ | ↔ | P/R | No primary role | Include only if a specific ER/mitochondrial stress model measures Ca²⁺ endpoints. |
| 10 | Clinical Translation Constraint | ↓ (constraint) | ↓ (constraint) | — | Metabolite-dominant exposure | Human absorption/metabolism exists, but many tumor-directed effects rely on higher in-vitro exposures; extract standardization and formulation matter. :contentReference[oaicite:8]{index=8} |
TSF legend: P: 0–30 min; R: 30 min–3 hr; G: >3 hr
Oleuropein — AD relevance: Oleuropein/olive leaf phenolics show neuroprotection in models via oxidative- and heat-shock/proteostasis stress responses, with reported reduction of Aβ and tau proteotoxicity in preclinical systems; human AD disease-modifying evidence is not established.
Primary mechanisms (conceptual rank):
1) ↓ Oxidative stress (ROS ↓; lipid peroxidation ↓; NRF2-linked defense ↑)
2) ↓ Neuroinflammation (NF-κB tone ↓)
3) Proteostasis support (heat-shock/stress-response pathways; context-dependent)
4) Aβ/tau proteotoxicity ↓ (preclinical)
Bioavailability / PK relevance: Human absorption/metabolism supports systemic exposure mainly as metabolites; brain relevance likely chronic/adaptive. :contentReference[oaicite:9]{index=9}
Clinical evidence status: Predominantly preclinical for AD mechanisms; limited AD-specific clinical endpoint evidence.
| Rank | Pathway / Axis | Cells | TSF | Primary Effect | Notes / Interpretation |
|---|---|---|---|---|---|
| 1 | ROS / lipid peroxidation | ↓ | P/R | Reduced oxidative burden | Central neuroprotection rationale for olive polyphenols (includes oleuropein/hydroxytyrosol pathways). :contentReference[oaicite:11]{index=11} |
| 2 | NRF2 axis | ↑ (context-dependent) | R/G | Stress-defense upshift | NRF2 modulation is repeatedly discussed for olive polyphenols in cognition-related health framing. :contentReference[oaicite:12]{index=12} |
| 3 | Neuroinflammation (NF-κB / cytokines) | ↓ | R/G | Lower inflammatory stress | Often paired with antioxidant effects; model-dependent magnitude. |
| 4 | Proteostasis / heat-shock stress responses | ↑ (supportive) | R/G | Improved handling of misfolded proteins | Oleuropein-rich olive leaf extract reduced Aβ and tau proteotoxicity via oxidative/heat-shock stress regulation in a C. elegans model. :contentReference[oaicite:13]{index=13} |
| 5 | Aβ / tau proteotoxicity | ↓ (preclinical) | G | Reduced pathology-linked toxicity | Evidence is stronger in models than in biomarker-confirmed human AD studies. :contentReference[oaicite:14]{index=14} |
| 6 | Ca²⁺ homeostasis / excitotoxic vulnerability | ↔ / stabilized (indirect) | P/R | Supportive (secondary) | Typically secondary to mitochondrial/redox support unless a study explicitly measures Ca²⁺ endpoints. |
| 7 | Clinical Translation Constraint | ↓ (constraint) | — | Preclinical-dominant AD evidence | Most AD-relevant mechanisms are model-based; human AD efficacy endpoints remain limited. :contentReference[oaicite:15]{index=15} |
TSF legend: P: 0–30 min; R: 30 min–3 hr; G: >3 hr