SummaryThe vitamin B12 (B12) content in seven species of seaweed that are consumed frequently in Hokkaido, Japan, was microbiologically measured using Escherichia coil 215. Asakusanori (Porphyra tenera), maruba-amanori (Porphyra suborbiculata) and akaba-gin-nansou (Rhodo giossum pulcherum) showed higher B12 content than the other species, although the content varied greatly among samples in the same species. A bioautography on a thin-layer plate holding a mixture of silica gel and cellulose, differentiation of B12 and its analogues using a binding specificity of intrinsic factor and haptocorrin, and comparison of the B12 concentra tion determined by the radioisotope dilution assay method using the intrinsic factor as the B12-binding protein with that by the bioassay method, predominantly showed B12 in maruba-amanori and B12 analogues in wakame (Undaria pinnatifida) and akaba-gin-nansou. The B12 uptake of akaba-gin-nansou from artificial seawater was similar to that of asaku sanori that contained only B12. Key Words vitamin B12, seaweed, B12 analogue, bioassay, radioassay, B12 uptakeThe occurrence of vitamin B12 (B12) was believed confined to the animal kingdom until the early 1950s when the B12 content was found to be higher in some seaweeds than beef or fish meat (1). Accordingly, seaweeds were expected to be promising resources of B12 (2) because of their vast production in the world. Most seaweeds contain not only B12 analogues that are active in mammals, but also other * To whom correspondence should be addressed . B12 analogues (2). The biological and nutritional significance of B12 and its analogues in seaweeds have not been reported. However, only Dagnelie et al. reported a deleterious effect on mean corpuscular volume in vegetarian children with a tendency of B12 deficiency when fed some seaweeds including noni (Porphyra family) (3). The findings of Dagnelie et al. may be due to B12 analogues in the seaweeds. The purpose of this study was to get some clue as to the significance of B12 analogues in some seaweeds for human nutrition. For this reason, B12 content was assayed microbiologically using Escherichia coli 215. It responds to a wider variety of B12 and B12 analogues than any other test organism (4). We measured the B12 contents in some commercially available seaweeds that were consumed frequently in Japan. The structure of B12 and its analogues in maruba-amanori (Porphyra suborbiculata ), akaba-gin-nansou (Rhodoglossum pulcherum) and wakame (Und aria pinnatifida) were characterized.Asakusanori containing only B12 has been known to take up B12 from artificial seawater (5). The relationship between B12 content and B12 uptake by a seaweed was worth studying. The B12 uptake by akaba-gin-nansou, composing exclusively of B12 analogues, was measured and compared with that of asakusanori.

Licorice root traditionally used as an anti-inflammatory drug exhibited an inhibitory effect on lysoPAF (platelet-activating factor) acetyltransferase in vitro: the ether soluble fraction of the crude drug produced a 27.3% inhibition at a concentration 10 microg/ml. From this fraction, licoricidin (1), 1-methoxyphaseollin (2), 6,8-diprenylgenistein (3) and 1-methoxyphaseollidin (4) were isolated as active components, whose IC50 values were 7.7, 57, 19 and 48 microM, respectively. Licoricidin (1) seems to be one of the most potent compounds of plant origin isolated so far.