| 1 |
Mevalonate prenylation signaling |
Ras/Rho prenylation ↓; proliferation ↓ |
Likely lower impact at dietary exposure |
G |
Growth signaling suppression |
Mechanistically central for monoterpene anticancer biology; strongest relevance where tumors rely on prenylated small GTPase signaling. |
| 2 |
Mitochondrial apoptosis |
MMP ↓; Bax ↑; Bcl-2 ↓; caspase-3 ↑; caspase-9 ↑; PARP cleavage ↑ |
Usually less cytotoxic at comparable non-transformed model exposure |
G |
Intrinsic apoptosis induction |
MMP↓, Bcl-2↓, and Casp3↑ tags; common endpoint across leukemia, colon, lung, and breast cancer models. |
| 3 |
Cell-cycle and cyclin D1 signaling |
Cyclin D1 ↓; G1 arrest ↑; proliferation ↓ |
Limited direct normal-cell evidence |
G |
Proliferation arrest |
Human breast-tissue data make this one of the more translationally credible axes. |
| 4 |
Autophagy linked apoptosis |
Autophagy ↑; apoptosis ↑ |
Context-dependent |
G |
Stress-amplified tumor cell death |
Autophagy appears pro-death in selected models but should be marked model-dependent because autophagy can also be adaptive. |
| 5 |
Mitochondrial ROS increase |
ROS ↑; GSH ↓; oxidative stress ↑ |
Antioxidant protection ↑ in oxidative-injury models |
R/G |
Redox stress in cancer cells |
Useful but concentration-sensitive; cancer-cell ROS findings should not be generalized to all systemic exposures. |
| 6 |
NRF2 and antioxidant response |
Mixed or insufficiently defined |
Antioxidant defense ↑ (context-dependent) |
G |
Context-dependent cytoprotection |
NRF2 is not the core anticancer mechanism for D-limonene; include only when specific studies show NRF2/HO-1 modulation in the model being indexed. |
| 7 |
NF-κB inflammatory signaling |
NF-κB linked cytokine signaling ↓; inflammatory survival signaling ↓ |
Inflammatory injury ↓ |
R/G |
Anti-inflammatory modulation |
More strongly supported in inflammatory disease models than direct oncology trials, but relevant to tumor-promoting inflammation. |
| 8 |
VEGF angiogenesis and metastasis |
VEGF signaling ↓; angiogenesis ↓; invasion/metastasis ↓ |
Potential wound-healing relevance uncertain |
G |
Anti-angiogenic and anti-invasive effect |
Supported mainly by preclinical cancer models and volatile-oil preparations enriched in D-limonene. |
| 9 |
Glycolysis and HIF-1α |
Not a primary established axis |
Not established |
G |
Secondary or indirect metabolic effect |
|
| 10 |
Chemosensitization |
Docetaxel effect ↑; tamoxifen effect ↑ (model-dependent) |
Normal-cell toxicity not consistently increased in available models |
G |
Adjunct cytotoxicity enhancement |
Preclinical adjunct signal only; timing, dose, formulation, and tumor context should be indexed carefully. |
| 11 |
Clinical Translation Constraint |
Clinical antitumor efficacy unproven |
GI intolerance at high oral doses; skin irritation or sensitization possible with concentrated topical exposure |
G |
Exposure and evidence limitation |
Food-flavor GRAS status does not equal oncology-dose safety; clinical data remain small and non-definitive. |