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In a recent study by the Department of Dermatology at the Mount Sinai-NYU Medical Center in New York, NY, aqueous extracts of green and black teas were revealed to ward off experimentally induced animal tumors, particularly those caused by ultraviolet (UV) light-induced skin carcinogenesis.

The study compared the impact of variable extractable fractions of green and black teas on scavenging hydrogen peroxide (H2O2), and UV irradiation-induced formation of 8-hydroxy 2'-deoxyguanosine (8-OHdG) in vitro.

These samples were extracted via serial chloroform, ethyl acetate, and n-butanol. The extracts were then divided into four subfractions. Upon their division, they were designated as GT1-4 for green tea and BT1-4 for black tea. The team then monitored their affect on various controlled tumor growths.

The study's results showed that both green and black tea exhibited a very strong scavenging capacity of exogenous H2O2 in a dose-dependent manner. Black tea appeared to scavenge H202 in a more effective manner than green tea.

Specifically, when tested individually, the results for green tea's potency as a scavenging agent for H202 were as follows: GT2 > GT3 > GT1 > GT4. The order for the potency as a scavenging agent for black tea was: BT2 > BT3 > BT4 > BT1.

The study also showed that the total fractions of green and black teas possessed the ability to dramatically inhibit the induction of 8-OHdG in a calf's thymus by all three portions of UV spectrum (UVA, B, and C).

Like the results found in the study of the scavenging ability of green and black tea in regards to H202, the subfractions from black tea showed a greater ability to thwart UV-induced 8-OHdG than those from green tea. The final results of both the green and black teas* effectiveness were remarkably similar.

At lower concentrations, the order of potency most effective at thwarting 8-OHdG by green tea was GT2 > GT3 > GT4 > GT1. Black tea seemed to thwart 8OHdG at all levels, and the order of potency was BT2 > BT3 > BT4 > BT1.

The effectiveness of all subfractions evened out when the dosage amounts were raised to the levels of what would be considered a high concentration.

When Epigallocatechin Gallate (EGCG), an ingredient found in green tea extract, was added to low concentrations of green and black tea extracts, the scavenging of H202 and the quenching of 8-OHdG was increased dramatically.

This provided compelling evidence that the role of EGCG in both thwarting 8-OHdG and scavenging H202 is significant in both green and black teas. These findings also indicated that if EGCG is extracted and used as a bolstering agent to green and black tea, this might hold scientific and medical significance in the future. Further study is definitely warranted.

Overall, the results of this test were powerful indicators of the role teas might play in being able to scavenge oxygen species and blocking UV-induced oxidative DNA damage.

These results could play a major role, or at the very least, be used as a weapon against future exposure. More study is needed, but the results were both compelling and promising.

Additionally, the EGCG addition and the subsequent results provide a very good indicator of its role in the antioxidant activities of tea extracts. The ability to scavenge oxygen species and block UV-induced oxidative DNA damage is a likely explanation, at least in demonstrating how green and black teas inhibit photocarcinogenesis.

These results possess great promise both in terms of regular use of teas as a scavenging agent and inhibitor. The study also suggests the benefits of using both in higher concentrated dosages. Their impact as a regular mechanism for avoiding exposure or warding off contamination has yet to be determined.