Study On Physiological And Biochemical Characteristics And Antitumor Activity Of The Selenium Enriched Ulva Fasciata

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 ofSe and was a good carrier for Se biotransformation. In the present study, the selenium-richculture characteristics, antioxidant activity and anti-cancer activity of U. fasciata weredetermined.The main resultswereas followed.1. Enrichment of selenium (Se) by seaweed is of great significance for mariculture. In thisstudy, U. fasciata was cultured with selenite (Na2SeO3) from concentration of0to1250mg L-1.Se accumulation in the algal biomass was linearly related to Na2SeO3concentration in theculture medium. Lower Se concentrations (≤750mg L-1) increased the activities of guaiacolperoxidase (GPX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) and thecontent of photosynthetic pigments.It also induced lipid peroxidation (LPO) and intracellularreactive oxygen species (ROS) levels, and the cell growth rate and concentrations of organic Sewith increased. In contrast, these changes were the opposite in U. fasciata exposed to Seconcentrations higher than750mg L-1. Furthermore, Ulva with enriched Se (Se-Ulva) was ableto remove inorganic nutrients effectively. After3days the concentration of total nitrogendecreased by62.08%, and the total phosphorus decreased68.49%in aquaria containing Se-Ulva.Therefore, U. fasciata is tolerant to Se, and Se-Ulvais a potential source of antioxidative foodand an effective control of eutrophication.2. The antioxidant activities of U. lacyuca L. aqueous extracts against DPPH and ABTS freeradicals were evaluated using spectrometric methods. The extracts effectively and rapidlyremoved 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, the IC50values for Se-PPC, PPC and VC against ABTS freeradical were76.40,54.11and60.69μg ml-1, respectively. Se-PPC exhibited significantly higheractivities than the VC. For DPPH free radicals, the IC50values of Se-PPC, PPC and VC were123.29,76.83and24.79μg ml-1, respectively. The results suggested selenium-enrichmentcultured U. lacyuca L. has potential applications in food with antioxidation function.3. Both selenium (Se) and U. lactuca L. have demonstrated anticancer potential. In thepresent study, the accumulation of Se in U. lactuca L. was investigated, and the anticanceractivities of Se-enriched U. lactuca L. extract (Se-PPC) against various cancer cells wereexamined. Three cell lines including breast cancer cells MCF-7, melanoma cells A375and lungcancer cells A549were treated in different concentrations of Se-PPC, and the IC50of these celllines were of:5.36±0.36,4.00±0.75,2.79±0.37μ g L-1, respective.The results showed thatSe-PPC triggered time and does-dependent apoptosis in A549human lung cancer cell, asevidenced by the accumulation of Sub-G1cell population, DNA fragmentation and nuclearcondensation. This apoptotic process was accompanied by the activation of caspase-8andcaspase-9and PARP cleavage, which demonstrated the involvement of Se-PPC in intrinsic andextrinsic signaling pathways. In conclusion, these results suggested that endogenous signaltransduction pathways mediated by mitochondria played an important role in the process ofapoptosis in A549cells induced by Se-PPC. The Se-PPC had potential application inchemoprevention of human lung cancers.