| Summary: | 碩士 === 靜宜大學 === 食品營養研究所 === 97 === Carcinoma is the major cause of death in Taiwan for 24 years. Leukemia is the thirteenth of cancer causes of death in adult and the first cancer causes of death in children in Taiwan. Recently, there is increasing interest in finding natural antioxidant from plants to prevent or delay leukemia development. Chlorella contains much kind of protein, amino acids, antioxidant enzymes and vitamins. This study was aimed to study the antioxidant activity of hot water extracts of Chlorella sorokiniana (CSE) and its effects on the growth of leukemia cell lines.
The in vitro study had showed that the CSE possessed antioxidative characteristics including α,α-diphenyl-β-picryl hydrazyl and 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfomic acid) radical-scavenging effects and Fe2+ -chelating ability. Furthermore CSE showed good antioxidant activity determined by phosphomolybdenum method. It was found that antioxidative activities of CSE increased with the increase of their concentrations.
The results of cell model indicated that CSE can decrease the percentage of viable cells and these effects were dose and time-dependent. Flow cytometry assay demonstrated that CSE induce cell cycle arrest on G0/G1 phase in a dose- and time-dependent manner. The morphology, DAPI staining and comet assay were conducted and they indicated that CSE induced WEHI-3 and HL-60 cells apoptosis. CSE decreased the glutathione levels of cells; however, the CSE increased superoxide dismutase and glutathione peroxidase in WEHI-3 and HL-60 cells. The results from Western blotting indicated that CSE induced apoptosis through the induction of AIF and Cytochrome c.
In the WEHI-3/BALB/c leukemia mice model, the animals were induced by injecting marine WEHI-3 cells and allowed 10 days to develop leukemia. The testing groups divided into five groups including control group, CSE group, WEHI-3 induced group, WEHI-3 + CSE group and WEHI-3 + CSE group. The results indicated that CSE can increase the survival and decrease the weight of spleen and liver of leukemia mice. The histopathological examination indicated that after pre-treatment with CSE, the spleen and liver markedly decreased number of neoplastic cells. CSE pre-treatment can increase the plasma total antioxidant status (TAS) and inhibit the leukemia-induced lipid peroxidation by preventing the decrease of glutathione levels, glutathione peroxidase, catalase and superoxide dismutase activity in liver of mice. In addition, CSE pre-treatment can increase the percentage of CD markers, CD11b and Mac-3, the activity of PBMC and NK cells by using the flow cytometric analysis.
In conclusion, the CSE has antioxidant activity. Leukemia cells (WEHI-3 and HL-60) were induced apoptosis by CSE. In addition, CSE can regular the redox system and immune system in the WEHI-3/BALB/c leukemia mice. These results suggest that CSE may have the anti-leukemia possibility and exert the antioxidative activity in vivo that may be used as a potential chmeopreventive agent.
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