Abstract: We have extracted and purified flavonoids as active ingredients from Ceylon green tea (Dilmah). In this project, an in vitro hypoxic model using human brain epithelial cells (HBEC) was studied with treatment of the tea extract before inducing hypoxia. We have tested the hypothesis that flavonoids extracted from Ceylon green tea act as potential therapeutic ingredient (s) to reduce oxidative stress in hypoxic cells through its antioxidant properties and its ability to reduce cerebral cellular death. The biochemical antioxidant tests show that the Ceylon green tea has 68% ± 2.8% inhibition property of scavenging of ABTS. The inhibition of pyrogallol red bleaching by HOCl from Ceylon tea was 79% ± 4.5%. After exposing to hypoxia, the cell viability was 29% ± 2.3% in the hypoxia control group but 41% ± 4.7% for flavonoids extract treated group. In LDH assay, flavonoids extract treated group had 75% ± 3.7% reducing of LDH release. The flavonoids extract treated groups significantly increased in antioxidant enzyme activity assays: the activity level of SOD [(1.5 ± 0.6) µmol/min/mg protein], CAT [(0.61 ± 0.06) µmol/min/mg protein], GPx [(2.6 ± 0.41) µmol/min/mg protein] and GST [(6.0 ± 2.4) µmol/min/mg protein] are significantly increased as compared with hypoxic control [(0.5 ± 0.52, 0.51 ± 0.04, 1.2 ± 0.35 and 3.1 ± 1.6) µmol/min/mg protein, respectively]. The study demonstrated a great clinical potential and opened a new avenue to prevent stroke by drinking Ceylon tea.

Key words: Stroke, Stroke, Hypoxia, Hypoxia, Flavonoids extract, Flavonoids extract, ABTS, ABTS, Pyrogallol red, Pyrogallol red, Lactate dehydrogenase, Lactate dehydrogenase, Superoxide dismutase, Superoxide dismutase, Catalase, Catalase