Table 3.
Polyphenols and gene modulations on insulin signalling pathways.
| Polyphenols/Conc. | Gene Affected | Function | Pathways | Cells/Tissue Type | Ref. |
|---|---|---|---|---|---|
| In vitro models | |||||
| OSPT (500 µg/mL) and OSPL (100 µg/mL) | ↑ Glut4, ↑ Nrf1, ↑ Mef2a, ↓ Acc2. | ↓ Hyperinsulinemia, ↓ Lipid peroxidation | Insulin sensitivity | Cells-C2C12 | [94] |
| Strigolactone GR24 and pinosylvin (60–100 µM) | ↑ SIRT1, ↑ Glut4 ↑ FOXO1 ↑ IRS-1 ↑ Akt2, | ↑ Insulin sensitivity, ↑ Glucose uptake | AKt2 | Cells-L6 myoblasts | [100] |
| Hibiscus sabdariffa (Various dose) | ↑ IRS-1, ↑ PI3K, ↓ DPP4, ↓ GLP-1R | ↑ Insulin sensitivity, ↓ Starch breakdown | Insulin receptor activation (PI3K) | Cells-HK-2 | [101] |
| C3G and PCA (10–100 µmol) | ↑ PPARγ, ↑ Glut4, ↑ Adiponectin | ↑ Glucose uptake | PPARγ | Cells-3T3-L1 | [10] |
| Rice bran extracts (10 μg/mL and 50 μg) | ↑ PPARγ, ↑ Adiponectin ↓ TNF-α | ↑ Insulin sensitivity | PPARγ/adipogenesis | Cells-3T3-L1 | [102] |
| Pigmented rice bran extracts (50 µg/mL) | ↑ INSR, ↑ PI3K, ↑ Glut4, ↓ DDP-4 | ↑ Insulin sensitivity, ↓ Starch breakdown | Akt2/PI3K | Cells-3T3-L1 | [103] |
| Aspalathin (1 µM) | ↑ Glut4, ↑ UCP2, ↓ CPT1, ↑ Bcl-1 | ↑ Cell viability, ↑ Insulin sensitivity, ↑ Glucose uptake | pAMPK | Cells-H9c2 | [104] |
| In vivo models | |||||
| Polyphenol-rich ethyl acetate fraction (200 mg/kg BW) | ↑ Insr, ↑ IRS1, ↑ IRS2 ↑ Akt2, ↑ Glut4 | ↑ Insulin sensitivity | IRS1/AKT | Skeletal muscle-Sprague-Dawley rats | [105] |
| Folium Mori Extract (2 g/kg BW) | ↑ IRS-1, ↑ PI3Kp85α, ↑ Glut-4 | ↑ Glucose uptake | IRS-1/PI3K/Glut-4 signalling | Skeletal muscle- Sprague-Dawley rats | [106] |
Glut4—Glucose transporter 4; Nrf1—Nuclear respiratory factor 1; Mef2a—Myocyte enhance factor 2A; ACC2—Acetyl CoA carboxylase 2; SIRT1—Sirtuin 1; FOXO1—Forkhead box O1; IRS-1—Insulin receptor substrate 1; Akt2—Protein kinase B; PI3K (p85α phosphorylated)—Phosphatidylinositol 3-kinase; DPP4—Dipeptidyl-peptidase-4; GLP-1R—Glucagon-like peptide 1 receptor; PPARγ—peroxisome proliferator-activated receptor gamma; TNF-α—Tumor necrosis factor alpha; INSR—insulin substrate receptor; UCP2—uncoupling protein 2; CPT1—carnitine palmitoyltransferase-1; Bcl-1—B Cell Lymphoma 1; IRS1—insulin receptor substrate 1; ↑—increased gene expression; ↓—decreased gene expression.