Proanthocyanidins / PKM2 Cancer Research Results

PACs, Proanthocyanidins: Click to Expand ⟱
Features:

Proanthocyanidins (PACs; condensed tannins) = oligomeric/polymeric flavan-3-ols (e.g., catechin/epicatechin units); abundant in grape seed, cocoa, cranberry, apple skin, pine bark. Degree of polymerization (DP) influences bioactivity and absorption.
Primary mechanisms (conceptual rank):
1) Redox modulation → direct ROS scavenging + metal chelation (Fe²⁺/Cu²⁺).
2) NRF2 activation → endogenous antioxidant enzymes (HO-1, NQO1, GCLC).
3) Anti-inflammatory signaling → ↓ NF-κB / ↓ COX-2 / ↓ cytokines.
4) Anti-proliferative / pro-apoptotic signaling in cancer (MAPK, PI3K/Akt modulation; dose-dependent).
5) Anti-angiogenic / anti-metastatic effects (VEGF, MMPs; model-dependent).
PK / bioavailability: monomers/low-DP oligomers absorbed; higher-DP polymers poorly absorbed but metabolized by gut microbiota to phenolic acids; plasma parent PAC levels modest vs many in-vitro studies.
In-vitro vs systemic exposure: many cancer studies use ≥10–100 µM equivalents; achievable circulating levels typically lower and largely conjugated/metabolite-driven.
Clinical evidence status: strongest human data in vascular/cardiometabolic endpoints; oncology evidence largely preclinical/adjunct.

Polyphenols found in cranberry, blueberry, and grape seeds.

Proanthocyanidin B2 (PB2) is a type of dimer flavonoid that is found in grape seed, pine bark, wine, and tea leaves [17]. PB2 has been shown to possess various bioactivities, including anti-oxidant, anti-inflammation, and anti-obesity activities, and it has also shown efficacy in the treatment of cancer, cardiovascular disease, type 2 diabetes, ulcerative colitis, as well as acute liver injury. PKM2 is the target of proanthocyanidin B2

PB2 also suppressed glucose uptake and lactate levels via the direct inhibition of the key glycolytic enzyme, PKM2.

Proanthocyanidins (PACs) — Cancer-Relevant Pathways

Rank Pathway / Axis Cancer Cells Normal Cells TSF Primary Effect Notes / Interpretation
1 ROS tone / redox balance ↓ (low–mod dose); ↑ (high concentration only) ↓ P→R Antioxidant; metal chelation Catechol-rich structure scavenges radicals; pro-oxidant shift reported at high doses in tumors (model-dependent).
2 NRF2 axis ↑ (context-dependent) ↑ R→G Endogenous antioxidant induction ↑ HO-1/NQO1; protective in normal tissue; may support tumor stress resistance (context-dependent).
3 NF-κB / inflammatory signaling ↓ ↓ R→G Anti-inflammatory Reduces cytokines, COX-2; anti-tumor microenvironment effect plausible.
4 PI3K/Akt / MAPK pathways ↓ proliferation (model-dependent) ↔ R→G Growth signaling attenuation Observed in breast, colon, prostate models; dose and DP dependent.
5 Apoptosis (caspase activation) ↑ (dose-dependent) ↔ / ↓ R→G Pro-apoptotic signaling Mitochondrial depolarization reported; often supra-physiologic exposure.
6 Angiogenesis (VEGF) ↓ (preclinical) ↔ G Anti-angiogenic ↓ VEGF expression in models; human oncologic data limited.
7 Ferroptosis axis ↓ (anti-lipid-ROS bias) ↓ P→R Lipid peroxidation inhibition Strong antioxidant property may counter ferroptotic strategies (context-dependent).
8 Clinical Translation Constraint — — — Bioavailability & dose gap High-DP PACs poorly absorbed; many in-vitro doses exceed realistic plasma exposure; adjunct role most plausible.

TSF Legend: P: 0–30 min | R: 30 min–3 hr | G: >3 hr


Proanthocyanidins (PACs) — Alzheimer’s Disease–Relevant Axes

Rank Pathway / Axis Cells (neurons/glia) TSF Primary Effect Notes / Interpretation
1 Lipid peroxidation / neuronal ROS ↓ P Neuroprotective antioxidant Reduces oxidative damage markers in models; aligns with AD oxidative stress hypothesis.
2 NRF2 activation ↑ R→G Endogenous antioxidant upregulation Supports neuronal resilience; mostly preclinical evidence.
3 Neuroinflammation (NF-κB) ↓ R→G Microglial modulation Reduced cytokine production in animal models.
4 Aβ aggregation / toxicity ↓ (preclinical) G Interference with amyloid aggregation Reported inhibition of Aβ fibrillization in vitro; human data limited.
5 BDNF / synaptic plasticity ↑ (model-dependent) G Neurotrophic signaling Observed in flavanol-rich cocoa/grape extract studies; translation to PAC isolates unclear.
6 Clinical Translation Constraint — — Dietary-level evidence Human trials mostly use flavanol-rich extracts; cognitive effects modest and stage-dependent.

TSF Legend: P: 0–30 min | R: 30 min–3 hr | G: >3 hr
PKM2, Pyruvate Kinase, Muscle 2: Click to Expand ⟱
Source:
Type: enzyme
PKM2 (Pyruvate Kinase, Muscle 2) is an enzyme that plays a crucial role in glycolysis, the process by which cells convert glucose into energy. PKM2 is a key regulatory enzyme in the glycolytic pathway, and it is primarily expressed in various tissues, including muscle, brain, and cancer cells.
-C-myc is a common oncogene that enhances aerobic glycolysis in the cancer cells by transcriptionally activating GLUT1, HK2, PKM2 and LDH-A
-PKM2 has been shown to be overexpressed in many types of tumors, including breast, lung, and colon cancer. This overexpression may contribute to the development and progression of cancer by promoting glycolysis and energy production in cancer cells.
-inhibition of PKM2 may cause ATP depletion and inhibiting glycolysis.
-PK exists in four isoforms: PKM1, PKM2, PKR, and PKL
-PKM2 plays a role in the regulation of glucose metabolism in diabetes.
-PKM2 is involved in the regulation of cell proliferation, apoptosis, and autophagy.
– Pyruvate kinase catalyzes the final, rate-limiting step of glycolysis, converting phosphoenolpyruvate (PEP) to pyruvate with the production of ATP.
– The PKM2 isoform is uniquely regulated and can exist in both highly active tetrameric and less active dimeric forms.
– Cancer cells often favor the dimeric form of PKM2 to slow pyruvate production, thereby accumulating upstream glycolytic intermediates that can be diverted into anabolic pathways to support cell growth and proliferation.
– Under low oxygen conditions, cancer cells rely on altered metabolic pathways in which PKM2 is a key player. – The shift to aerobic glycolysis (Warburg effect) orchestrated in part by PKM2 helps tumor cells survive and grow in hypoxic conditions.

– Elevated expression of PKM2 is frequently observed in many cancer types, including lung, breast, colorectal, and pancreatic cancers.
– High levels of PKM2 are often correlated with enhanced tumor aggressiveness, poor differentiation, and advanced clinical stage.

PKM2 in carcinogenesis and oncotherapy

Inhibitors of PKM2:
-Shikonin, Resveratrol, Baicalein, EGCG, Apigenin, Curcumin, Ursolic Acid, Citrate (best known as an allosteric inhibitor of phosphofructokinase-1 (PFK-1), a key rate-limiting enzyme in glycolysis) potential to directly inhibit or modulate PKM2 is less well established

Full List of PKM2 inhibitors from Database
-key connected observations: Glycolysis↓, lactateProd↓, ROS↑ in cancer cell, while some result for opposite effect on normal cells.
Tumor pyruvate kinase M2 modulators

Flavonoids effect on PKM2
Compounds name IC50/AC50uM Effect
Flavonols
1. Fisetin 0.90uM Inhibition
2. Rutin 7.80uM Inhibition
3. Galangin 8.27uM Inhibition
4. Quercetin 9.24uM Inhibition
5. Kaempferol 9.88uM Inhibition
6. Morin hydrate 37.20uM Inhibition
7. Myricetin 0.51uM Activation
8. Quercetin 3-b- D-glucoside 1.34uM Activation
9. Quercetin 3-D -galactoside 27-107uM Ineffective
Flavanons
10. Neoeriocitrin 0.65uM Inhibition
11. Neohesperidin 14.20uM Inhibition
12. Naringin 16.60uM Inhibition
13. Hesperidin 17.30uM Inhibition
14. Hesperitin 29.10uM Inhibition
15. Naringenin 70.80uM Activation
Flavanonols
16. (-)-Catechin gallateuM 0.85 Inhibition
17. (±)-Taxifolin 1.16uM Inhibition
18. (-)-Epicatechin 1.33uM Inhibition
19. (+)-Gallocatechin 4-16uM Ineffective
Phenolic acids
20. Ferulic 11.4uM Inhibition
21. Syringic and 13.8uM Inhibition
22. Caffeic acid 36.3uM Inhibition
23. 3,4-Dihydroxybenzoic acid 78.7uM Inhibition
24. Gallic acid 332.6uM Inhibition
25. Shikimic acid 990uM Inhibition
26. p-Coumaric acid 22.2uM Activation
27. Sinapinic acids 26.2uM Activation
28. Vanillic 607.9uM Activation


Scientific Papers found: Click to Expand⟱
2396- PACs,    PKM2 is the target of proanthocyanidin B2 during the inhibition of hepatocellular carcinoma
- in-vitro, HCC, HCCLM3 - in-vitro, HCC, SMMC-7721 cell - in-vitro, HCC, Bel-7402 - in-vitro, HCC, HUH7 - in-vitro, HCC, HepG2 - in-vitro, Nor, L02
TumCP↓, TumCCA↓, Apoptosis↑, GlucoseCon↓, lactateProd↓, PKM2↓, Glycolysis↓, HK2↓, PFK↓, OXPHOS↑, ChemoSen↑, HSP90↓, Hif1a↓,

Showing Research Papers: 1 to 1 of 1

* indicates research on normal cells as opposed to diseased cells
Total Research Paper Matches: 1

Pathway results for Effect on Cancer / Diseased Cells:


Redox & Oxidative Stress ⓘ

OXPHOS↑, 1,  

Core Metabolism/Glycolysis ⓘ

GlucoseCon↓, 1,   Glycolysis↓, 1,   HK2↓, 1,   lactateProd↓, 1,   PFK↓, 1,   PKM2↓, 1,  

Cell Death ⓘ

Apoptosis↑, 1,  

Protein Folding & ER Stress ⓘ

HSP90↓, 1,  

Cell Cycle & Senescence ⓘ

TumCCA↓, 1,  

Migration ⓘ

TumCP↓, 1,  

Angiogenesis & Vasculature ⓘ

Hif1a↓, 1,  

Drug Metabolism & Resistance ⓘ

ChemoSen↑, 1,  
Total Targets: 13

Pathway results for Effect on Normal Cells:


Total Targets: 0

Scientific Paper Hit Count for: PKM2, Pyruvate Kinase, Muscle 2
Query results interpretion may depend on "conditions" listed in the research papers.
Such Conditions may include : 
  -low or high Dose
  -format for product, such as nano of lipid formations
  -different cell line effects
  -synergies with other products 
  -if effect was for normal or cancerous cells

Filter Conditions: Pro/AntiFlg:%  IllCat:%  CanType:%  Cells:%  prod#:136  Target#:772  State#:%  Dir#:1
  wNotes=0  sortOrder:rid,rpid

 

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