Description: <p>Isoorientin is specifically luteolin-6-C-glucoside</p>
<p><b>Isoorientin</b> — a naturally occurring flavone C-glycoside, specifically luteolin-6-C-glucoside, also known as homoorientin. It is a dietary/plant polyphenol rather than an approved drug and occurs in multiple medicinal and food plants. Isoorientin is structurally related to orientin, but differs in the position of C-glucosylation. Its anticancer pharmacology is dominated by redox-dependent mitochondrial apoptosis and suppression of pro-survival signaling, while in non-cancer inflammatory and neurological models it generally behaves as an antioxidant and anti-inflammatory GSK3β/NF-κB modulator. This context-dependent redox behavior is important when interpreting apparently opposite ROS effects.<br>
-buckwheat sprouts contain orientin, isoorientin, vitexin, isovitexin, and rutin</p>
<p><b>Primary mechanisms (ranked):</b></p>
<ol>
<li>ROS-dependent mitochondrial apoptosis in cancer cells, with mitochondrial membrane-potential loss, cytochrome-c release, Bax/Bcl-2 shift and caspase activation.</li>
<li>PI3K/Akt survival-pathway suppression, contributing to apoptosis and reduced proliferation.</li>
<li>MAPK/STAT3/NF-κB modulation, typically with ↑ JNK/p38 and ↓ ERK, STAT3 and NF-κB signaling in susceptible cancer models.</li>
<li>Wnt/β-catenin/STAT3 suppression, reducing cancer stem-cell characteristics, epithelial-mesenchymal transition, invasion and tumorigenicity.</li>
<li>AMPK activation, associated with reduced proliferation, invasiveness, EMT-associated signaling and VEGF secretion in pancreatic cancer models.</li>
<li>Cell-cycle arrest, commonly G2/M in lung and gastric cancer models, involving ↓ cyclins/CDKs and ↑ p21/p27.</li>
<li>Autophagy induction accompanying apoptosis in selected models, particularly HepG2 cells, through ROS-, PI3K/Akt-, JNK-, p38- and p53-linked signaling.</li>
<li>Anti-inflammatory GSK3β inhibition with secondary NRF2/HO-1 activation in non-cancer cells; this is more relevant to neuroprotection and inflammatory disease than to the primary anticancer mechanism.</li>
</ol>
<p><b>Bioavailability / PK relevance:</b> Oral systemic exposure is low. In rats, absolute oral bioavailability was approximately 9%, with low circulating parent isoorientin after a 150 mg/kg oral dose and substantially greater formation of sulfated metabolite. Low aqueous solubility and extensive first-pass metabolism are important translational constraints. Reported intravenous terminal half-life in rats is approximately 1.7–2.1 hours.</p>
<p><b>In-vitro vs systemic exposure relevance:</b> Many anticancer experiments use approximately 20–160 µM isoorientin, while oral administration produces low circulating parent-compound exposure. These concentrations therefore commonly exceed plausibly achievable systemic free-isoorientin concentrations after conventional oral dosing. Local gastrointestinal exposure, metabolites, high-dose experimental administration and specialized delivery systems may not follow this limitation to the same degree.</p>
<p><b>Clinical evidence status:</b> <b>Preclinical.</b> Anticancer activity is supported by multiple cell studies and a small number of animal/xenograft studies, including oral squamous-cell carcinoma models. A 2026 systematic review identified 12 eligible anticancer studies but no established human oncology efficacy. Isoorientin is not an approved anticancer drug and there is no established therapeutic human cancer dose.</p>
<h3>Isoorientin Cancer Mechanisms</h3>
<table border="1" cellpadding="4" cellspacing="0">
<thead>
<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>
</thead>
<tbody>
<tr>
<td>1</td>
<td>ROS-dependent mitochondrial apoptosis</td>
<td>↑ ROS; ↓ mitochondrial membrane potential; ↑ cytochrome c; ↑ Bax/Bcl-2 ratio; ↑ caspase-3</td>
<td>↓ ROS or ↔ (context-dependent)</td>
<td>P→G</td>
<td>Apoptosis</td>
<td>Core anticancer mechanism in liver, lung and gastric models. NAC substantially suppresses apoptosis, supporting a causal role for ROS rather than ROS being only a downstream marker.</td>
</tr>
<tr>
<td>2</td>
<td>PI3K/Akt survival signaling</td>
<td>↓ Akt phosphorylation; ↓ survival signaling</td>
<td>↔ (context-dependent)</td>
<td>R→G</td>
<td>Growth inhibition and apoptosis</td>
<td>Strong mechanistic evidence in HepG2 and gastric cancer models; interacts with ROS and mitochondrial apoptosis.</td>
</tr>
<tr>
<td>3</td>
<td>MAPK STAT3 NF-κB signaling</td>
<td>↑ JNK; ↑ p38; ↓ ERK; ↓ STAT3; ↓ NF-κB</td>
<td>↓ excessive MAPK/NF-κB activation</td>
<td>R→G</td>
<td>Apoptosis and reduced pro-survival transcription</td>
<td>ROS-dependent signaling is particularly well demonstrated in A549 lung cancer cells. In inflammatory normal-cell models, suppression of MAPK/NF-κB is predominantly cytoprotective.</td>
</tr>
<tr>
<td>4</td>
<td>Wnt β-catenin STAT3 and cancer stemness</td>
<td>↓ β-catenin; ↓ p-STAT3; ↓ TCF1/TCF7; ↓ LEF1; ↓ stemness</td>
<td>Not established</td>
<td>G</td>
<td>Reduced EMT, invasion and tumor initiation</td>
<td>Supported by oral squamous-cell carcinoma cell and xenograft models. Particularly relevant to metastatic and cancer-stem-cell phenotypes.</td>
</tr>
<tr>
<td>5</td>
<td>AMPK and angiogenic signaling</td>
<td>↑ AMPK; ↓ VEGF; ↓ invasiveness</td>
<td>↔ or ↑ metabolic AMPK signaling (context-dependent)</td>
<td>R→G</td>
<td>Growth and invasion suppression</td>
<td>Mechanistically prominent in pancreatic cancer; PRKAA1 knockdown substantially attenuated the reported anticancer effects.</td>
</tr>
<tr>
<td>6</td>
<td>Cell-cycle control</td>
<td>↑ p21; ↑ p27; ↓ cyclin B1; ↓ CDK1/2; ↑ G2/M arrest</td>
<td>Not established</td>
<td>G</td>
<td>Proliferation arrest</td>
<td>G2/M arrest is reported in lung and gastric cancer; phase effects vary among tumor models.</td>
</tr>
<tr>
<td>7</td>
<td>Autophagy apoptosis coupling</td>
<td>↑ Beclin-1; ↑ LC3-II; ↑ autophagy</td>
<td>Context-dependent</td>
<td>R→G</td>
<td>Autophagic and apoptotic cell death</td>
<td>Best established in HepG2 cells. Pharmacologic inhibition suggests reciprocal interaction between autophagy and apoptosis rather than two independent responses.</td>
</tr>
<tr>
<td>8</td>
<td>EMT migration and invasion</td>
<td>↓ EMT; ↓ migration; ↓ invasion</td>
<td>Not established</td>
<td>G</td>
<td>Antimetastatic phenotype</td>
<td>Downstream of Wnt/β-catenin/STAT3, Akt and AMPK signaling depending on tumor model.</td>
</tr>
<tr>
<td>9</td>
<td>Chemosensitization</td>
<td>↑ cisplatin cytotoxicity (model-dependent)</td>
<td>Not established</td>
<td>G</td>
<td>Potential combination therapy</td>
<td>Demonstrated preclinically in oral squamous-cell carcinoma. Human benefit and therapeutic index remain unknown.</td>
</tr>
<tr>
<td>10</td>
<td>GSK3β NRF2 HO-1 inflammatory regulation</td>
<td>Context-dependent</td>
<td>↓ GSK3β activity; ↑ NRF2; ↑ HO-1; ↓ NF-κB</td>
<td>R→G</td>
<td>Anti-inflammatory and cytoprotective activity</td>
<td>More strongly established in macrophage, microglial and neurological disease models than as a primary cancer mechanism.</td>
</tr>
<tr>
<td>11</td>
<td>Clinical Translation Constraint</td>
<td>Low oral exposure relative to many effective in-vitro concentrations</td>
<td>Low oral exposure relative to many experimental concentrations</td>
<td>G</td>
<td>PK and evidence limitation</td>
<td>Rat oral bioavailability is approximately 9%; substantial first-pass sulfation occurs. Most anticancer evidence remains cellular or animal, with no established human oncology dose or clinical efficacy.</td>
</tr>
</tbody>
</table>
<p><b>TSF legend:</b> P: 0–30 min R: 30 min–3 hr G: >3 hr</p>
<br><br>
<p><b>Isoorientin and Alzheimer’s disease</b> — Isoorientin has meaningful preclinical AD relevance centered on inhibition of GSK3β and suppression of neuroinflammation. In APP/PS1 mice, chronic oral administration reduced GSK3β overactivation, tau hyperphosphorylation, amyloid-β deposition and microglial inflammation while improving long-term potentiation and spatial memory. Cell studies additionally show suppression of Aβ-induced ROS, NF-κB, iNOS, COX-2 and inflammatory cytokines. This evidence remains preclinical; no established human AD efficacy or therapeutic dose has been demonstrated.</p>
<p><b>Primary mechanisms (ranked):</b></p>
<ol>
<li>GSK3β inhibition, reducing pathological tau phosphorylation and influencing downstream inflammatory and redox signaling.</li>
<li>Reduction of amyloid-β-associated pathology and Aβ-induced microglial activation.</li>
<li>NF-κB suppression with reduced TNF-α, IL-6, iNOS and COX-2.</li>
<li>Secondary NRF2/HO-1 activation and antioxidant protection in neural and microglial cells.</li>
<li>Protection of synaptic plasticity and cognitive function in animal models.</li>
</ol>
<p><b>Clinical evidence status:</b> <b>Preclinical.</b> Evidence includes cellular models and APP/PS1 transgenic mice, but there is no established clinical efficacy in human Alzheimer’s disease.</p>
<h3>Isoorientin Alzheimer’s Mechanisms</h3>
<table border="1" cellpadding="4" cellspacing="0">
<thead>
<tr>
<th>Rank</th>
<th>Pathway / Axis</th>
<th>Modulation</th>
<th>Primary Effect</th>
<th>Notes / Interpretation</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>GSK3β</td>
<td>↓ activity</td>
<td>Reduced pathological kinase signaling</td>
<td>Isoorientin has been characterized as a substrate-competitive GSK3β inhibitor; GSK3β is a particularly relevant target because of its roles in tau phosphorylation and neuroinflammation.</td>
</tr>
<tr>
<td>2</td>
<td>Tau phosphorylation</td>
<td>↓ p-tau</td>
<td>Reduced tau pathology</td>
<td>Observed in APP/PS1 mouse brain and mechanistically consistent with reduced GSK3β activity.</td>
</tr>
<tr>
<td>3</td>
<td>Amyloid beta pathology</td>
<td>↓ Aβ deposition</td>
<td>Reduced amyloid burden</td>
<td>Reduced Aβ deposition has been reported in APP/PS1 mice; the precise contribution of direct amyloid processing versus secondary signaling effects remains uncertain.</td>
</tr>
<tr>
<td>4</td>
<td>Microglial NF-κB inflammation</td>
<td>↓ NF-κB; ↓ TNF-α; ↓ IL-6; ↓ iNOS; ↓ COX-2</td>
<td>Reduced neuroinflammation</td>
<td>Supported by LPS- and Aβ-stimulated microglial models and by reduced activated microglia in APP/PS1 mice.</td>
</tr>
<tr>
<td>5</td>
<td>NRF2 HO-1 antioxidant response</td>
<td>↑ NRF2; ↑ HO-1; ↓ ROS</td>
<td>Neuroprotection</td>
<td>Secondary cytoprotective mechanism particularly evident in inflammatory microglial models.</td>
</tr>
<tr>
<td>6</td>
<td>Synaptic plasticity</td>
<td>↑ long-term potentiation</td>
<td>Improved synaptic function</td>
<td>Observed electrophysiologically in APP/PS1 mice after chronic treatment.</td>
</tr>
<tr>
<td>7</td>
<td>Cognition and spatial memory</td>
<td>↑ memory performance</td>
<td>Functional neurological improvement</td>
<td>Animal-model outcome; should not be interpreted as demonstrated clinical cognitive efficacy.</td>
</tr>
<tr>
<td>8</td>
<td>Clinical Translation Constraint</td>
<td>Low oral bioavailability; human efficacy not established</td>
<td>Translation limitation</td>
<td>Animal efficacy is encouraging but human pharmacokinetics, CNS exposure, therapeutic dose and clinical effectiveness remain undetermined.</td>
</tr>
</tbody>
</table>