富硒裂片石莼的生理生化特征及其抗肿瘤活性研究-水生生物学专业论文.docxVIP

暨南大 暨南大学硕士学位论文 PAGE PAGE IV ABSTRACT Selenium is an essential trace element for humans, which has many physiological functions. Ulva fasciata, a fast-growing seaweed, was found to possess a good tolerance to high levels of Se and was a good carrier for Se biotransformation. In the present study, the selenium-rich culture characteristics, antioxidant activity and anti-cancer activity of U. fasciata were determined. The main resultswereas followed. Enrichment of selenium (Se) by seaweed is of great significance for mariculture. In this study, U. fasciata was cultured with selenite (Na2SeO3) from concentration of 0 to 1250 mg L-1. Se accumulation in the algal biomass was linearly related to Na2SeO3 concentration in the culture medium. Lower Se concentrations (≤ 750 mg L-1) increased the activities of guaiacol peroxidase (GPX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) and the content of photosynthetic pigments.It also induced lipid peroxidation (LPO) and intracellular reactive oxygen species (ROS) levels, and the cell growth rate and concentrations of organic Se with increased. In contrast, these changes were the opposite in U. fasciata exposed to Se concentrations higher than 750 mg L-1. Furthermore, Ulva with enriched Se (Se-Ulva) was able to remove inorganic nutrients effectively. After 3 days the concentration of total nitrogen decreased by 62.08%, and the total phosphorus decreased 68.49% in aquaria containing Se-Ulva. Therefore, U. fasciata is tolerant to Se, and Se-Ulvais a potential source of antioxidative food and an effective control of eutrophication. The antioxidant activities of U. lacyuca L. aqueous extracts against DPPH and ABTS free radicals were evaluated using spectrometric methods. The extracts effectively and rapidly removed ABTS and DPPH free radicals, and showed a dose- and time-dependent manner, indicating the potent antioxidant activities under both hydrophilic and hydrophobic conditions. Under the optimized systems,