Table 1.

Major targets of action of EGCG in the lung.

Targets	Modulation by EGCG	Biological Effects
Cell surface receptors
EGFR VEGFR	Inhibition inhibition	inhibited proliferation of lung non-small cancer cells [134] anti-angiogenic action [135]
TLR4	inhibition	anti-inflammatory action [136]
SARS-CoV-2 spike receptor binding domain ACE2	inhibition	inhibition of SARS-CoV-2 from entering into cells [40]
Intracellular signaling pathways
MAPK	inhibition	anti-inflammatory and anti-tumorous action [39,137]
PI3K/Akt/eNOS	inhibition	vasorelaxation, anti-inflammatory and anti-tumorous action [138]
COX-2	inhibition	anti-inflammatory and anti-tumorous action [139]
Cytosolic calcium	elevation	various biological actions including induction of apoptosis [140]
AMPK	activation	anti-tumorous action [141]
Nuclear transcription factors
NF-κB	inhibition	anti-inflammatory action, anti-oxidant action, inhibited proliferation of cancer cells [142]
AP-1	inhibition	anti-inflammatory action, inhibition of cell growth [71,143]
Nrf2/HO-1	activation	anti-oxidant action, anti-inflammatory action [106]
STAT1	inhibition	inhibited apoptosis of lung epithelial cells, anti-inflammatory and anti-tumorous action [144,145,146]
STAT3	inhibition	induction of apoptosis and anti-proliferative effect, anti-inflammatory action [147,148]

Abbreviations: ACE2: angiotensin-converting enzyme 2, AMPK: adenosine monophosphate-dependent kinase, AP-1: activator protein 1, COX-2: cyclooxygenase-2, EGCG: epigallocatechin-gallate, EGFR: epidermal growth factor receptor, eNOS: endothelial nitric oxide synthase, HO-1: heme oxygenase-1, MAPK: mitogen-activated protein kinase, NF-κB: nuclear factor kappa-B, Nrf2: nuclear factor erythroid-derived 2-like 2, PI3K/Akt: phosphoinositide-3-kinase-protein kinase B/Akt, SARS-CoV-2: severe acute respiratory syndrome coronavirus 2, STAT1/3: signal transducer and activator of transcription 1/3, TLR4: toll-like receptor 4, VEGFR: vascular endothelial growth factor receptor.