Induction of mitophagy by green tea extracts and tea polyphenols: A potential anti-aging mechanism of tea

Tea consumption has been associated with anti-aging effects, however, the mechanisms involved are not well understood. Prompting mitochondrial health via the induction of mitophagy has recently been proposed as a novel anti-aging mechanism and the anti-aging properties of a few polyphenols including urolithin A have been linked to their abilities to induce mitophagy. Teas, rich in polyphenols, may also produce anti-aging effects through the induction of mitophagy. To test this hypothesis, a green tea extract and a few common tea polyphenols (catechins), were evaluated as potential mitophagy inducers in normal human fibroblasts. Mitophagy was detected by confocal microscopy and confirmed by Western blot analysis. A catechin-rich green tea extract (polyphenol content of 98%) induced mitophagy in normal human fibroblasts in a dose-dependent manner with a maximum effective concentration at ∼5 μg/mL, demonstrating comparable efficacy to urolithin A. Tea catechins also induced similar levels of mitophagy at an effective concentration of 5 μM for (-)-epicatechin gallate, EGCG and (-)-epicatechin, and 10 μM for (+)-catechin and (-)-epigallocatechin. These results demonstrate that the polyphenols in teas are powerful inducers of mitophagy in human fibroblast cells and induction of mitophagy may play an important role in the anti-aging mechanism of teas.