title: Isolation and structural determination of two novel phlorotannins from the brown alga Ecklonia kurome Okamura, and their radical scavenging activities.
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 IC(50) 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.
authors: Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan. myama@biochem.tohoku.ac.jp
authors: Mari
authors: M
authors: Yotsu-Yamashita
authors: Sawako
authors: S
authors: Kondo
authors: Shinya
authors: S
authors: Segawa
authors: Yi-Chin
authors: YC
authors: Lin
authors: Haruhiko
authors: H
authors: Toyohara
authors: Hisatomi
authors: H
authors: Ito
authors: Keiichi
authors: K
authors: Konoki
authors: Yuko
authors: Y
authors: Cho
authors: Takafumi
authors: T
authors: Uchida
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology; D001205:Ascorbic Acid / Q000737:chemistry; D001572:Benzofurans / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D002460:Cell Line; D045744:Cell Line, Tumor; D004147:Dioxins / Q000737:chemistry; D005452:Fluoresceins / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D051379:Mice; D000459:Phaeophyceae / Q000737:chemistry* / Q000378:metabolism; D010696:Phloroglucinol / Q000737:chemistry; D010851:Picrates / Q000737:chemistry; D059808:Polyphenols / Q000737:chemistry; D013634:Tannins / Q000737:chemistry* / Q000494:pharmacology*; D024502:alpha-Tocopherol / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001572:Benzofurans; D001713:Biphenyl Compounds; D004147:Dioxins; D005452:Fluoresceins; D016166:Free Radical Scavengers; D010851:Picrates; D059808:Polyphenols; D013634:Tannins; C503840:dieckol; C516536:phlorofucofuroeckol B; C064093:phlorofucofuroeckol A; C029569:diacetyldichlorofluorescein; C004931:1,1-diphenyl-2-picrylhydrazyl; D010696:Phloroglucinol; D024502:alpha-Tocopherol; D001205:Ascorbic Acid