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KMID : 0613820180280111321
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Journal of Life Science
2018 Volume.28 No. 11 p.1321 ~ p.1331
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Isolation and Identification of Pheophytin, a Photosensitizer from Nostoc commune that Induces Apoptosis in Leukemia and Cancer Cells
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Park Jae-Eun
Lee Jun-Young
Lee Min-Woo
Jang Eun-Jin
Hong Chang-Oh
Kim Keun-Ki
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Abstract
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The aim of this study was to separate the photosensitizer that induces apoptosis of U937 and SK- HEP-1 cells from Nostoc commune. Dried N. commune was extracted with CH2Cl2/MeOH (1:1) to separate the photosensitizer using various chromatographic techniques. The isolated compound was identified as pheophytin a (C55H74N4O5) with a molecular weight of 870. Its photodynamic activities were assessed under different irradiation conditions (light and non-light) at the same concentration range of 1.15-23.0 μM. The apoptosis inducing activity in U937 or SK-HEP-1 cells appeared only in the light. The mechanisms underlying the pheophytin a-mediated photodynamic inhibition of cancer cells were further investigated by examining cell morphology changes, cytotoxicity, caspase-3/7 activity, fluorescence staining, flow cytometry analysis, and DNA fragmentation in these two cell lines. The positive control and the light irradiation group showed typical apoptotic responses, including morphological changes, cytotoxicity, caspase activity, nucleus shrinkage owing to chromatin condensation, DNA laddering, and the presence of apoptotic bodies. Cytotoxicity markedly increased in a dose-dependent manner after a 12 hr exposure. Caspase-3/7 activity was higher in U937 cells than in SK- HEP-1 cells. Apoptosis induction therefore appeared to be both concentration- and light-dependent. In conclusion, pheophytin a, isolated from the blue green alga N. commune, had a photodynamic apoptosis-inducing effect on U937 and SK-HEP-1 cells. The findings reported here can be used as basic data for the development of next-generation photosensitizers from N. commune.
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KEYWORD
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Apoptosis, caspase, Nostoc commune, pheophytin a, photodynamic
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