Antitumor effects of seaweed extracts
It appears that the first reported research in Japan on anti-tumor substances in seaweed came in the middle of 1970. The extracts referred to here are substances obtained through fractionation by means of organic solvents, gel filtration, etc. of substances extracted with cold water, hot water, etc., or of extracted substances. First, Nakazawa et al. injected supernatants of extracts of 12 species of green algae, 27 species of brown algae, and 24 species of red algae into mice that had Ehrlich ascites carcinoma transplanted into their abdominal cavities and investigated the anticancer effects. Ehrlich ascites cancer was discovered by Ehrlich in 1906 as a spontaneous, transplantable breast cancer in mice used in cancer experiments and is a malignant ascites tumor that was converted to ascites form in 1930. The researchers observed antiproliferative effects on cancer cells in the crude polysaccharide fraction, crude protein fraction, and low molecular mass fraction obtained by gel filtration fractionation of the ammonium sulfate precipitate from dialysis fluid of aqueous solutions of members of Sargassaceae such as Sargassum horneri, Sargassum siliquastrum, and Sargassum hemiphyllum. Among these the largest effect was observed in the crude polysaccharide fraction believed to be a mixture of water-soluble alginic acid and fucoidan. They have subsequently prepared fractions corresponding to the above-mentioned crude polysaccharide fraction and detected high antitumor activity in a fraction thought to consist of only acidic polysaccharides (fucoidan) and a fraction thought to have several kinds of amino acids mixed in. In 1976 Ito and Sugiura reported that ethanol precipitate with molecular weight of 10,000 and over from dialysis fluid of hot water extract of Sargassum thunbergii has inhibitory effects on the proliferation of Ehrlich ascites carcinoma that had been transplanted into the abdominal cavities of mice. Such reports suggest that acidic polysaccharides are antitumor substances.
Ehrlich carcinoma transplanted into mice growth inhibition rate through seaweed extract powder oral administration(%)
|Type of algae||Applied dose (mg/kg/day)||Growth inhibition rate (%)|
|Codium fragile||as above||43.4|
|Scytosiphon lomentaria||as above||69.8|
|Laminaria japonica||as above||57.6|
|Hizikia fusiforme||as above||49.7|
|Sargassum hornery||as above||38.6|
|Porphyra yezoensis||as above||53.2|
|Acanthopeltis japonica||as above||38.5|
|Corallina pilulifera||as above||38.4|
However, because acidic saccharides from brown algae include not only fucoidan but also alginic acid, it became necessary to make determinations using purified, refined samples. In subsequent research regarding the antitumor activity of seaweed extracts, Yamamoto et al. of Kitasato University injected extracts of Sargassum fulvellum, Laminaria angustata, Laminaria longissima, and Laminaria japonica into the abdominal cavities of dd mice with subcutaneously transplanted sarcoma 180 solid carcinoma and observed a marked inhibition rate of cancer cell proliferation in all but Laminaria japonica. In this case the inhibition rates were 90-95%. Yamamoto et al. have investigated longevity promoting effects using hot water extracts of 10 species of seaweed including the green alga Monostroma nitidum and the red algae Porphyra tenera along with L1210 leukemia cells from dialysis fluid, and they have identified effects in 6 of them. Slimy substances such as alginic acid and fucoidan that are found in brown algaes started to attract attention due to research results such as these. These factors led Furusawa and Nisizawa to conclude that the antitumor activity of seaweed polysaccharides seems to be caused by the activation of the response system mediating the host and differs from the immune regulatory substances in chemical drugs. Please have a look at our fucoidan products.
- H.Ito and M.Sugiura 1976 Chem. Pharm. Bull., 24, 1114-1115
- I.Yamamoto at al. 1982. Bot. Mar., 25, 455-457