| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 100 === Oxidative stress will contribute to the accumulation of ROS, and result in many chronic diseases, such as cancers, cardiac diseases, neurodegenerative diseases, and aging etc. via damaging DNA, proteins, and cellular membranes in the body. Therefore, intaking the dietary supplement containing antioxidants is gradually becoming a portion of modern life. However, the researches about the antioxidant functions always merely focus on the in vitro chemical reactions, for example, DPPH radical scavenging activity, chemical colorimetric methods using Ammonium thiocyanate and iron (II) chloride tetrahydrate solution, and so forth. If we can analyze these materials by the ways which are more closed to the actual organism, the antioxidant functions of them can be more convinced.
Nuclear factor-E2 (Erythroid 2)-related factor 2, Nrf-2, is a transcription factor and also an important regulation factor of antioxidation pathway. When our bodies are damaged by oxidative stress, the factor can translocate into the nucleus and binds to the antioxidant response element (ARE) to induce the expression of downstream genes, including many related enzymes and proteins about antioxidation, and then act to reduce oxidative damages. At first, the study utilizes RT-q-PCR as a screening method to detect the expression of the downstream gene- NQO1. Finally, we discovered that Bracteanolide A , the pure compound contained higher in Tradescantia albiflora Kunth, at the concentration of 50 μM can apparently induce the expression of NQO1 mRNA among the 11 compounds. Other experiments also indicate the compound has the ability to induce the expression of Nrf2, NQO1, and HO-1 on the protein level. Besides, it can increase the amount of Nrf2 which translocates into the nucleus to elevate its activity. If pretreating the cells with Bracteanolide A, ROS induced by hydrogen peroxide can be effectively reduced and DNA damages will be strongly lowered. Last but the most important, it can inhibit the cell death caused by hydrogen peroxide. Overall, the main component of Tradescantia albiflora Kunth, Bracteanolide A, possesses the protective effect on oxidative damaged cells.
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