Aim: 

This study examine the effects of epigallocatechin-3-gallate (EGCG), the most abundant component among green tea polyphenols, on tumor cell survival, proliferation and programmed death.

Methods: 

NCI-H292 were cultured in 24-well plates and 24 hours later were treated with a series of concentrations (5-500 mM) of EGCG for 24 h and 48 h. After incubation, cells were treated by MTT to evaluate cell viability. The absorbance was measured at 570 nm and the cell survival ratio was expressed as a percentage of the control. We evaluate the antioxidant or pro-oxidant activity of EGCG at different concentrations (10–500 mM) by Crocin Bleaching Assay (CBA).

Results: 

After 24 h of treatment, cell viability increased with concentration of EGCG from 5 to 40 mM, compared to untreated cells; by contrast, at higher concentration we found a reduction of cell viability. After 48 h of treatment, we found an increment of cell viability with concentration of EGCG from 5 to 20, compared to untreated cells; by contrast, higher concentration determined a reduction of cell viability. In both cases, we found 50% of cell death at 200 mM of EGCG. The EGCG behaves as an antioxidant within the concentration range of 10–50 micro while it turns into a pro-oxidant when the concentration is grown from 50 up to 500 micro.

Conclusion: 

Lower concentration EGCG stimulates cell growth, while higher concentration determined cell death. MTT test results correlate with the CBA, since the proliferative effects of EGCG decay when it looses its anti-oxidative properties, and thus we find cell death. So, we are going to perform flow cytometer to quantify both necrotic and apoptotic phenomena at these concentrations.