Description: <b>Caffeic acid</b> is a polyphenol antioxidant found in coffee, fruits, vegetables, and herbs. It may have anti-inflammatory, anticancer, anti-aging, and other health benefits.<br>
Caffeic acid (CA) is a dietary hydroxycinnamic acid found widely in plant foods and in coffee largely as chlorogenic acids (caffeoylquinic acids). CA is generally antioxidant / anti-inflammatory and is frequently reported to modulate Nrf2 and NF-κB signaling, with downstream effects on survival pathways (PI3K/AKT), MAPKs, cell cycle, and apoptosis in preclinical cancer models. A notable mechanistic nuance is a context-dependent pro-oxidant effect described in the presence of copper (Cu), where CA can drive oxidative DNA damage in vitro (often discussed as potentially relevant to tumors with higher copper levels).<br>
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-Caffeic acid phenethyl ester, the main representative component of propolis<br>
-Black chokeberry 141.14 mg/100 g F<br>
-Sunflower seed, meal 8.17 mg/100 g FW<br>
-Common sage, dried 26.40 mg/100 g FW<br>
-Ceylan cinnamon 24.20 mg/100 g FW<br>
-Nutmeg 16.30 mg/100 g FW<br>
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-Dual capacity of CA to act as an antioxidant during carcinogenesis and as a pro-oxidant against cancer cells, promoting their apoptosis or sensitizing them to chemotherapeutic drugs.<br>
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Pathways:<br>
-Caffeic acid is a potent antioxidant<br>
-Caffeic acid may also exhibit pro-oxidant behavior. At higher concentrations( 50–100 µM ?) or/and in the presence of transition metal ions (such as copper or iron), caffeic acid can participate in Fenton-like reactions, potentially leading to increased ROS generation.<br>
-Shown to inhibit NF-κB activation<br>
-Inhibitory effects on MAPK/ERK Pathway<br>
-PI3K/Akt Signaling Pathway<br>
-Activation of the Nrf2/ARE pathway <br>
-Cell cycle arrest at various checkpoints<br>
-Angiogenesis Inhibition<br>
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Caffeic acid typically shows low oral bioavailability (sometimes only a few percent of the ingested dose is systemically available) and a short plasma half-life (around 1–2 hours in animal models).<br>
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<p><b>Caffeic acid</b> — Caffeic acid is a dietary hydroxycinnamic acid polyphenol present in coffee, fruits, vegetables, and many herbs, and is also generated from hydrolysis of chlorogenic acids. It is formally classified as a small-molecule plant phenolic acid with redox-active, anti-inflammatory, and signal-modulating properties. Standard abbreviations include <b>CA</b> for caffeic acid; it should be distinguished from <b>CAPE</b> (caffeic acid phenethyl ester), which is a different propolis-derived ester with overlapping but not identical pharmacology. In cancer research, CA is best viewed as a pleiotropic preclinical modulator of inflammatory signaling, stress adaptation, metabolism, apoptosis, invasion, and angiogenesis, with translation limited by rapid conjugation and generally low free-aglycone systemic exposure.</p>
<p><b>Primary mechanisms (ranked):</b></p>
<ol>
<li>Suppression of inflammatory/pro-survival transcription, especially IL-6/JAK/STAT3 and NF-κB signaling.</li>
<li>Redox modulation, usually antioxidant/cytoprotective in normal cells but capable of context-dependent pro-oxidant activity in cancer models, particularly with transition metals or higher in-vitro exposure.</li>
<li>Down-modulation of ERK and PI3K/AKT survival signaling with downstream effects on proliferation and apoptosis.</li>
<li>Induction of mitochondrial apoptosis and cell-cycle arrest in susceptible tumor models.</li>
<li>Anti-invasive and anti-angiogenic effects, including reduced MMP/EMT outputs and suppression of STAT3-HIF-1α-VEGF signaling.</li>
<li>Metabolic reprogramming in some models, including AMPK-linked disruption of tumor energy homeostasis and glycolytic dependence.</li>
<li>Clinical translation constraint: extensive phase-II metabolism means circulating exposure is dominated by conjugated metabolites rather than sustained free caffeic acid.</li>
</ol>
<p><b>Bioavailability / PK relevance:</b> CA is absorbable in humans, but after oral intake much of the circulating material appears rapidly as sulfate, glucuronide, and methylated metabolites rather than persistent free aglycone. Peak plasma timing is typically early, and delivery is constrained less by gut uptake than by fast metabolic conversion and short-lived free exposure.</p>
<p><b>In-vitro vs systemic exposure relevance:</b> Many anticancer studies use tens of micromolar CA, and some mechanistic claims depend on 50–100 µM or higher conditions that are not reliably reproduced as sustained free systemic exposure after ordinary oral intake. Accordingly, anti-inflammatory/adjuvant interpretations translate better than claims requiring strong direct tumor-cidal free-drug concentrations; metal-assisted pro-oxidant effects are especially context-dependent.</p>
<p><b>Clinical evidence status:</b> <b>Primarily preclinical.</b> The cancer evidence base consists mainly of cell and animal studies, with some adjunct/chemosensitization signals. Human oncology evidence remains very limited; at least one registered esophageal squamous cell carcinoma trial has been reported, but caffeic acid is not an established anticancer drug or standard adjunct.</p>
<h3>Mechanistic matrix</h3>
<table border="1" cellpadding="4" cellspacing="0">
<tr>
<th>Rank</th>
<th>Pathway / Axis</th>
<th>Cancer Cells</th>
<th>Normal Cells</th>
<th>TSF</th>
<th>Primary Effect</th>
<th>Notes / Interpretation</th>
</tr>
<tr>
<td>1</td>
<td>IL-6 / JAK / STAT3 signaling</td>
<td>↓</td>
<td>↔ / ↓ inflammatory tone</td>
<td>R, G</td>
<td>Anti-survival transcription</td>
<td>One of the cleaner current cancer axes for CA itself; suppression links to reduced proliferation, migration, and anti-apoptotic signaling.</td>
</tr>
<tr>
<td>2</td>
<td>NF-κB inflammatory transcription</td>
<td>↓</td>
<td>↓ inflammatory stress</td>
<td>R, G</td>
<td>Anti-inflammatory / anti-survival</td>
<td>Consistent across reviews and multiple models, but CA is generally a weaker and less canonical NF-κB inhibitor than CAPE.</td>
</tr>
<tr>
<td>3</td>
<td>ROS redox modulation</td>
<td>↔ / ↑ (context-dependent)</td>
<td>↓ oxidative injury</td>
<td>P, R</td>
<td>Redox reprogramming</td>
<td>CA is usually antioxidant in normal tissues, yet can become pro-oxidant in tumor or copper-rich settings; direction is strongly model- and dose-dependent.</td>
</tr>
<tr>
<td>4</td>
<td>ERK and PI3K / AKT survival signaling</td>
<td>↓</td>
<td>↔</td>
<td>R, G</td>
<td>Growth and resistance suppression</td>
<td>Frequently appears upstream of reduced clonogenicity, apoptosis sensitization, and lower chemoresistance in acidic or stressed tumor states.</td>
</tr>
<tr>
<td>5</td>
<td>Mitochondrial apoptosis</td>
<td>Bax ↑, caspase-3 ↑, Bcl-2 ↓</td>
<td>↔ / relative sparing</td>
<td>G</td>
<td>Cell death execution</td>
<td>Usually a downstream endpoint rather than the first event; strongest in susceptible cell lines and higher in-vitro exposure.</td>
</tr>
<tr>
<td>6</td>
<td>Cell-cycle machinery</td>
<td>cyclin D ↓, arrest ↑</td>
<td>↔</td>
<td>G</td>
<td>Cytostasis</td>
<td>Phase of arrest varies by model; best treated as a secondary phenotype following signaling and redox changes.</td>
</tr>
<tr>
<td>7</td>
<td>MMP / EMT / invasion programs</td>
<td>MMP2/9 ↓, EMT ↓, migration ↓</td>
<td>↔</td>
<td>G</td>
<td>Anti-invasive effect</td>
<td>Supported in several tumor models, though part of the older invasion literature is stronger for caffeic-acid derivatives than for CA itself.</td>
</tr>
<tr>
<td>8</td>
<td>STAT3-HIF-1α-VEGF angiogenesis axis</td>
<td>HIF-1α ↓, VEGF ↓</td>
<td>↔</td>
<td>G</td>
<td>Anti-angiogenic support</td>
<td>Includes in-vivo support in renal carcinoma xenograft work; useful mechanistically, but still preclinical.</td>
</tr>
<tr>
<td>9</td>
<td>AMPK and tumor energy metabolism</td>
<td>AMPK ↑, glycolytic dependence ↓</td>
<td>↔ / context-dependent</td>
<td>R, G</td>
<td>Metabolic stress</td>
<td>Relevant in selected cancers rather than universally. Better framed as model-dependent metabolic rewiring than as a universal glycolysis inhibitor.</td>
</tr>
<tr>
<td>10</td>
<td>NRF2 antioxidant response</td>
<td>↔ / ↑ (context-dependent)</td>
<td>↑</td>
<td>R, G</td>
<td>Stress adaptation</td>
<td>Important for normal-cell protection and toxicity mitigation. In tumors, NRF2 activation may be beneficial, neutral, or counterproductive depending on context, so it is not a uniformly favorable anticancer axis.</td>
</tr>
<tr>
<td>11</td>
<td>Clinical Translation Constraint</td>
<td>Free CA exposure limited</td>
<td>Conjugated metabolites predominate</td>
<td>—</td>
<td>PK limitation</td>
<td>Human absorption occurs, but circulating chemistry is dominated by rapid conjugation. Many direct in-vitro tumoricidal concentrations likely exceed sustained free systemic levels achievable by routine oral dosing.</td>
</tr>
</table>
<p><b>Time-Scale Flag (TSF):</b> P / R / G</p>
<ul>
<li><b>P</b>: 0–30 min (rapid redox/metal interactions; early signaling shifts)</li>
<li><b>R</b>: 30 min–3 hr (acute stress-response + transcription signaling changes)</li>
<li><b>G</b>: >3 hr (gene-regulatory adaptation and phenotype outcomes)</li>
</ul>