Preparation and Intestinal Immunostimulating Activity of Low Molecular Weight Alginate from Saccharina (Laminaria) Species in Japan

We studied the structure of alginates extracted from five commercial Saccharina (Laminaria) species including three varieties (eight samples in all) harvested in Hokkaido, Japan. The algae used were Saccharina japonica, S. japonica var. diabolica, S. japonica var. ochotensis, S. japonica var. religiosa, S. longissima, S. coriacea, S. angustata, and S. sculpera (Kjellmaniella crassiforia). These alginates have molar fractions of mannuronic acid (F(M)) ranging from 0.68 to 0.76 and weight average molecular weights (M(w)s) ranging from 511,000 to 616,000. Alginate samples from both S. angustata (F(M) = 0.76) and S. longissima (F(M) = 0.68) showed intestinal immunological activity through Peyer’s patch cells of C3H/HeJ mice. Low molecular weight S. angustata alginate (F(M) = 0.75, M(w) = 70,000) degraded using a wet pulverizing system showed higher activity than the native one.