In general, the absorbances of all samples tested varied less than 15% from those of the positive control. Changes of this magnitude are not indicative of cytotoxicity, but may instead indicate a decrease in cellular XAV-939 metabolism. The results of the SRB assay are shown in Table 2. The rates of cellular proliferation in treated cultures are normalised to those of positive control cells. In agreement with previously published studies (Hwang et al., 2006, Jung et al., 2001, Yang and Wang, 2011 and Yang et al., 1998), the green tea extract demonstrated antiproliferative activity in HT29 cells; however, this

antiproliferative activity was not observed in PG100 cells. Independent of the particular response of each cell line, the biotransformation of the green tea extract resulted in a higher degree of inhibition of cellular growth at almost every concentration tested in both cell lines. Unmodified EGCG demonstrated a strong cytocidal antiproliferative

effect at a range of concentrations in PG100 Everolimus cells. Interestingly, biotransformation of EGCG inhibited this cytocidal effect without significantly affecting its antiproliferative activity. This finding points to potentially interesting avenues for future studies of cancer chemoprevention. Studies by Morley et al. (2005) and Malhomme de la Roche et al. (2010) investigated whether ingestion of green tea by healthy human volunteers afforded any genotoxic protection to their circulating peripheral leukocytes upon experimental exposure to various amounts of UVR radiation. Both studies

used the comet assay to determine the genotoxic protection potential of green tea on human cells and demonstrated that up to 90 min following green tea ingestion, there was a significant decrease (p < 0.05) in DNA damage (detected by alkaline single cell gel electrophoresis (the comet assay)) in peripheral leukocytes when they were subsequently exposed to 12 min of UVA/VIS irradiation. In the present work, the comet assay was performed on cells treated with biotransformed or unmodified green tea extracts. These experiments demonstrated significantly reduced Tail Moment (TM) values when compared to positive control SPTLC1 cells, demonstrating that green tea extract provided protection against DNA damage (Table 3). The TM data obtained for these samples were statistically smaller than the cell control. This is a clear indication of DNA damage protection capacity of the tested samples. The TM values appeared to be negatively correlated with the concentration of green tea extract and were slightly higher in samples treated with biotransformed extract than in samples treated with unmodified extract; however, TM values of all treated cell cultures were statistically similar and significantly smaller than those of control cell cultures.