Nitric oxide-mediated antitumor activity induced by the extract from Grifola frondosa (Maitake mushroom) in a macrophage cell line, RAW264.7.

We have investigated D-fraction (MDF) extracted from Grifola frondosa (Maitake mushroom) on the inducible nitric oxide synthase (iNOS)-mediated nitric oxide (NO) production in RAW264.7 (RAW) cells, a murine monocyte/macrophage cell line, with special reference to antitumor activity of MDF against human hepatoma-derived huH-1 cells. MDF could induce iNOS mRNA expression in RAW cells in a dose range of more than 30 microg/ml, but the effect of 10 microg/ml of MDF was negligible. The iNOS mRNA expression induced by 100 microg/ml of MDF was 6 hrs later, but lasted for a longer time than that of lipopolysaccharide (LPS), a representative iNOS inducer. Although iNOS mRNA levels in MDF-stimulated cells were almost equal to LPS-stimulated cells at the peak time, the cumulative amount of nitrite was only about 50% compared with that of LPS-treated cells. When huH-I cells were cultured in MDF containing media in a 24-well plate with inserted porous bottom in the presence or absence of RAW cells, the viability of huH-1 cells decreased significantly only in the presence of RAW cells in MDF dose-dependent manner. This antitumor activity of RAW cells in the presence of MDF was abolished or attenuated by the addition of L-NAME, a NOS inhibitor, confirming that this phenomenon is due to iNOS-mediated NO production by RAW cells, but not direct cytotoxic activity of MDF against huH-1 cells. These data suggest that MDF is a novel inducer for iNOS which contributes at least in part to antitumor activity of MDF.

Taste-active components in some foods: a review of Japanese research.

Japanese research of taste-active components in seafoods, meat and tomatoes is reviewed. The omission (or addition) test with synthetic extracts simulating natural extracts was employed in most of that research. In abalone, sea-urchin, snow crab, scallop and short-necked clam, glutamic acid (Glu) and glycine were recognized commonly to be taste-active. It was also reported that the synergism between Glu and 5'-ribonucleotides and the presence of sodium and chloride ions were required to produce the characteristic taste of each food. In dried skipjack meat and salted salmon eggs, umami substances such as Glu and inosine 5'-monophosphate (IMP) were found to be important contributors to their tastes as well. The brothy taste of beef, pork and chicken soups could be reproduced by free amino acids, IMP and sodium chloride, indicating their important roles in producing the taste. A potential effect of Glu and aspartic acid on the taste of tomatoes was observed. Studies of the flavor-enhancing effects on soups and umami solutions of sulfur-containing compounds in garlic are also described.

Purification and properties of an aminopeptidase from Alaska pollack, Theragra chalcogramma, roe.

An aminopeptidase was isolated from a soluble fraction of Alaska pollack roe in the presence of 2-mercaptoethanol by fractionation with ammonium sulfate and column chromatography on DEAE-cellulose, hydroxyapatite, and Sephadex G-200. The molecular weight of the enzyme was estimated to be 125,000 and 105,000 by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. The pH optimum and temperature optimum were 7.2 and 35 degrees C, respectively. The purified enzyme hydrolyzed various alpha-aminoacyl beta-naphthylamides and cleaved L-Ala-beta-naphthylamide most rapidly. Both a sulfhydryl group and a divalent metal ion are essential for activity; however, the enzyme was inhibited when incubated with divalent metal ions. Puromycin, chelating agents, and thiol reagents were effective inhibitors. The enzyme was also inhibited by L-amino acids, in particular glutamic acid. Thus, the Alaska pollack roe aminopeptidase resembles soluble alanyl aminopeptidase [EC 3.4.11.14].

Occurrence and distribution of D-cysteinolic acid in fish and shellfish.

1. An unknown compound which is very similar to taurine was detected in the extract of sardine Sardinops melanosticta. 2. It was identified as D-cysteinolic acid: 2-amino-3-hydroxy-1-propanesulfonic acid from instrumental analysis. 3. This may be the first report in which the occurrence of D-cysteinolic acid in fish has been demonstrated. 4. Of 14 species of fish and shellfish examined, the presence of this compound was confirmed in 7 species.

Bioactive marine metabolites, IV. Isolation and the amino acid composition of discodermin A, an antimicrobial peptide, from the marine sponge Discodermia kiiensis.

An antimicrobial peptide, discodermin A, has been isolated from the marine sponge Discodermia kiiensis. The peptide showed antimicrobial activity as well as an inhibition of starfish embryo development. It appeared to be a tetradecapeptide consisting of D-Cys(O3H), L-Asp, L-MeGlu, L-Thr (2 moles), Sar, D-Pro, D-Ala, D- and L-t-Leu, D-Leu, L-Phe, D-Trp, and L-Arg.

Comparison of carotenoids in the ovaries of marine fish and shellfish.

1. The following carotenoids were isolated and identified: astaxanthin diester, tunaxanthin monoester, astaxanthin monoester, tunaxanthin, astaxanthin, doradexanthin, lutein, zeaxanthin, idoxanthin, triol and tetrol from nine species of fish; astaxanthin diester, astaxanthin monester, astaxanthin, doradexanthin, zeaxanthin, idoxanthin and tetrol from four species of crustacean, astaxanthin, pectenolone, pectenoxanthin, pectenol and tetrol from four species of scallop. 2. Tunaxanthin monoester and astaxanthin diester were major carotenoids in skipjack and Pacific cod, respectively. 3. The concentration of carotenoids ranged 0.065-1.95, 1.30-5.91 and 1.56-7.15 mg per 100 g ovary for fish, crustacean and scallop, respectively. 4. The species- and tissue-specificity of ovarian carotenoids and their possible role are discussed.