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Photo-induced antibacterial activity of a porphyrin derivative isolated from the harmful dinoflagellate Heterocapsa circularisquama

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タイトル: Photo-induced antibacterial activity of a porphyrin derivative isolated from the harmful dinoflagellate Heterocapsa circularisquama
著者: Wencheng, Li / Cho, Kichul / Yamasaki, Yasuhiro / Takeshita, Satoshi / Hwang, Kiju / Kim, Daekyung / Oda, Tatsuya
発行日: 2018年 8月
出版者: Elsevier B.V.
引用: Aquatic Toxicology, 201, pp.119-128; 2018
抄録: The dinoflagellate Heterocapsa circularisquama is highly toxic to bivalves. However, significant toxicity to finfish species has not been reported. We previously found that H. circularisquama has light-dependent haemolytic agents. Purification and chemical structural analyses revealed that the haemolytic agent H2-a is a porphyrin derivative, which exhibits light-dependent cytotoxicity toward tumour cells. To clarify the biological activity of H2-a further, its antibacterial activities against Gram-positive and Gram-negative bacteria were investigated in this study. A fraction (F5) equivalent to H2-a purified from the methanol extract of H. circularisquama showed potent light-dependent bactericidal activity toward Staphylococcus aureus, and the activity was concentration- and light illumination time-dependent; however, Escherichia coli was highly resistant to F5. Electron microscopic observation suggested that F5 induces morphological changes in S. aureus in a light-dependent manner. Further analysis using other bacterial species showed that the Gram-positive bacterium Bacillus subtilis was more sensitive than the Gram-negative bacteria Pseudomonas aeruginosa and Vibrio alginolyticus. These results indicate that F5 is a photo-induced antibacterial agent with relatively higher specificity to Gram-positive bacteria. Iodometric assay suggested that singlet oxygen was generated from light-illuminated F5. Histidine, a specific singlet oxygen scavenger, markedly inhibited the photosensitising antibacterial activity of F5 against S. aureus, suggesting the involvement of singlet oxygen in antibacterial activity. The antibacterial spectrum of F5 was evidently different from that of 5,10,15,20-tetra (N,N,N-trimethylanilinium) porphyrin tetratosylate, a commercially available porphyrin compound with antibacterial activity. Our results demonstrate that H. circularisquama has a novel antibacterial photosensitiser, a porphyrin derivative, with relatively higher specificity to Gram-positive bacteria. To the best of our knowledge, this is the first study to discover a porphyrin derivative with antibacterial activity in marine microalga.
キーワード: Antibacterial activity / Harmful dinoflagellate / Heterocapsa circularisquama / Photosensitising agent / Porphyrin derivative / Single oxygen
URI: http://hdl.handle.net/10069/38492
ISSN: 0166445X
DOI: 10.1016/j.aquatox.2018.06.004
権利: © 2018 Elsevier B.V. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
資料タイプ: Journal Article
原稿種類: none
出現コレクション:080 学術雑誌論文

引用URI : http://hdl.handle.net/10069/38492



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