Table 3.
Molecular mechanisms of tea polyphenols in activating nrf2 and inhibiting nf-κb.
| Tea Polyphenol | Target Pathway | Mechanism of Action | Biological Effect | Reference |
|---|---|---|---|---|
| Epigallocatechin gallate (EGCG) | Nrf2 Activation | Promotes Nrf2 movement into the nucleus by altering Keap1 cysteine residues | Increases levels of antioxidant enzymes (e.g., SOD, GSH-Px) and reduces oxidative stress | (Lv, et al., 2022) |
| EGCG | NF-κB Inhibition | Prevents IκBα breakdown and stops NF-κB from entering the nucleus | Lowers production of inflammatory cytokines (e.g., TNF-α, IL-6) | (Talebi, et al., 2021) |
| Theaflavins | Nrf2 Activation | Helps Nrf2 separate from Keap1 and boosts gene expression through ARE | Enhances antioxidant defenses and protects cells from oxidative damage | (Zhang, et al., 2019) |
| Theaflavins | NF-κB Inhibition | Stops NF-κB activation by blocking IKK phosphorylation | Reduces inflammation and prevents tissue damage | (O'Neill, et al., 2021) |
| Catechins | Nrf2 Activation | Triggers Nrf2 phosphorylation through PKC and MAPK pathways | Increases production of detoxifying enzymes | (Talebi, Talebi, Farkhondeh, Mishra, İlgün and Samarghandian, 2021) |
| Catechins | NF-κB Inhibition | Prevents NF-κB from binding to DNA and reduces p65 subunit phosphorylation | Reduces inflammation and oxidative stress | (Sheng, Sun, Tang, Yu, Wang, Zheng, Li and Sun, 2023) |
| Epicatechin (EC) | Nrf2 Activation | Stabilizes Nrf2 by preventing Keap1 from marking it for degradation | Strengthens antioxidant defenses and reduces lipid peroxidation | (Granado-Serrano, et al., 2010) |
| Epicatechin | NF-κB Inhibition | Reduces NF-κB activation by stopping IKK complex formation | Lowers levels of inflammatory markers (e.g., CRP, IL-1β) | (Ponnian, 2022) |
| Gallocatechin gallate (GCG) | Nrf2 Activation | Activates Nrf2 through ERK and PI3K/Akt signaling pathways | Boosts glutathione production and lowers ROS levels | (Pullikotil, et al., 2012) |
| Gallocatechin gallate | NF-κB Inhibition | Stops NF-κB activation by preventing IκBα phosphorylation | Reduces release of inflammatory cytokines and oxidative damage | (Mokra, Joskova and Mokry, 2022) |
| Thearubigins | Nrf2 Activation | Helps Nrf2 move into the nucleus and bind to ARE | Increases antioxidant gene expression and reduces oxidative stress | (Datta, et al., 2022) |
| Theasinensins | Nrf2 Activation | Boosts Nrf2 activity by stabilizing its interaction with ARE | Enhances cellular antioxidant defenses and reduces oxidative damage | (Jiang, et al., 2021) |
| Theasinensins | NF-κB Inhibition | Blocks NF-κB activation by inhibiting IKKβ activity | Reduces inflammation and oxidative stress in liver tissues | (Howes and Simmonds, 2014) |