Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Zoology

This study was concerned with the investigation of antioxidant and prooxidant abilities of different H. sabdariffa extracts on glutathione and its related antioxidant enzymes in rat lung tissue and human lung cultured fibroblasts (MRC-5) subjected to oxidative stress inducer. Hibiscus sabdariffa extracted by 70% ethanol at 95{u00B0}C for15 min have the highest phenolic, flavonoid, anthocyanin contents compared to aqueous and 30 % ethanol extracts. Aqueous and 30 % ethanol extracts have the powerful antioxidant capacities. HPLC analysis of the three H. sabdariffa extracts showed that cyanidin 3-O-glucoside chloride, chlorogenic acid and delphinidin derivatives were the major constituents. Hydrolysis of H. sabdariffa calyx increased the concentration of caffeic acid and quercetin as a result of chlorogenic acid and rutin disappearance, respectively. Lung tissues of six experimental adult male albino rat groups subjected to oxidative stress inducer and 30 % ethanolic H. sabdariffa extracts were collected. Pretreatment of rats with H. sabdariffa ethanolic extract followed by tert-butyl hydroperoxide (t-BHP) injection partially blocked the effect of the t-BHP, as indicated by the oxidative stress markers. In rats lungs homogenates, glutathione (GSH), malondialdehyde levels (MDA) and lactate dehydrogenase activity returned back almost to the normal level. The antioxidant enzymes catalase (CAT) and glutathione {u2013}S {u2013} transferase (GST) were increased, while glutathione peroxidase (GPx) and glutathione reductase (GR) were not affected

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