Isolation and characterization of a phenolic antioxidant from the Pacific oyster (Crassostrea gigas).
Using an oxygen radical absorbance capacity (ORAC) assay, antioxidant activity was detected in the ethanol extract of the Pacific oyster, which was purified by sequential extraction with organic solvents. The ethyl acetate fraction showed the strongest antioxidant activity and was further purified, yielding a single compound [as assessed by thin-layer chromatography (TLC) and reverse-phase high-performance liquid chromatography (HPLC)]. This compound was identified as 3,5-dihydroxy-4-methoxybenzyl alcohol on the basis of (1)H and (13)C nuclear magnetic resonance (NMR), heteronuclear multiple-bond correlation (HMBC), and electrospray ionization-mass spectrometry (ESI-MS) spectral analyses, a conclusion that was confirmed by chemical synthesis. The concentration of the compound was 6.7 mg/100 g of whole oyster meat wet weight. This amphiphilic antioxidant retarded the copper-mediated oxidation of low-density lipoproteins (LDLs) and the generation of thiobarbituric acid reactive substances. Furthermore, the compound showed substantial antioxidant activity using the ORAC and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays compared to natural antioxidants. Although the same compound was previously found in brown algae, its presence in other organisms and antioxidant activity are reported here for the first time.
Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan.
Mitsugu
M
Watanabe
Hirotoshi
H
Fuda
Shigeki
S
Jin
Toshihiro
T
Sakurai
Futaba
F
Ohkawa
Shu-Ping
SP
Hui
Seiji
S
Takeda
Takayuki
T
Watanabe
Takao
T
Koike
Hitoshi
H
Chiba
D000818:Animals; D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D049896:Crassostrea / Q000737:chemistry*; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry* / Q000302:isolation & purification*; D021241:Spectrometry, Mass, Electrospray Ionization
D000975:Antioxidants; D010636:Phenols