Isolation and structural determination of two novel phlorotannins from the brown alga ecklonia kurome okamura, and their radical scavenging activities

Mari Yotsu-Yamashita, Sawako Kondo, Shinya Segawa, Yi Chin Lin, Haruhiko Toyohara, Hisatomi Ito, Keiichi Konoki, Yuko Cho, Takafumi Uchida

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

Two novel phlorotannins with a molecular weight of 974, temporarily named 974-A and 974-B, were isolated from the polyphenol powder prepared from the edible marine brown alga Ecklonia kurome Okamura, and their chemical structures were determined by spectroscopic method. The isolated yield of the total of 974-A and 974-B was approximately 4% (w/w) from the polyphenol powder. In 974-A, the carbon at the C2' position in the A ring of phlorofucofuroeckol-A forms a C-C bond with the carbon at the C2'' position of the C ring of triphloretol-B, while in 974-B, phlorofucofuroeckol-B and triphloretol-B form a C-C bond in the same manner as in 974-A. These structures were supported by high resolution-MS/MS data. To evaluate the antioxidant activities, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and intracellular radical scavenging assay, using 2',7'-dichlorofluorescin diacetate (DCFH-DA), were performed for 974-A, 974-B, and four known phlorotannins. The results of the DPPH assay showed that the IC50 values of 974-A, 974-B, phlorofucofuroeckol-A, and dieckol were significantly smaller than those of phlorofucofuroeckol-B, phloroglucinol, α-tocopherol, and ascorbic acid. Furthermore, the DCFH-DA assay suggested that 974-A, 974-B, and dieckol reduce intracellular reactive oxygen species most strongly among the tested compounds.

Original languageEnglish
Pages (from-to)165-183
Number of pages19
JournalMarine Drugs
Volume11
Issue number1
DOIs
Publication statusPublished - 2013 Jan

Keywords

  • Ecklonia kurome
  • NMR
  • Phlorotannins
  • Radical scavenging activity
  • Structural determination

ASJC Scopus subject areas

  • Drug Discovery

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