Wakame (Undaria pinnatifida) modulates hyperphosphatemia in a rat model of chronic renal failure

In chronic renal failure, inorganic phosphate (Pi) retention speeds up the progression to end-stage renal disease. The current therapy for hyperphosphatemia in patients with chronic renal failure consists of dietary Pi restriction combined with administration of Pi binders, but each therapy has practical problems. Thus, the discovery of foods or nutrients that inhibit Pi absorption may be useful for the treatment of hyperphosphatemia. In the present study, we investigated whether wakame (Undaria pinnatifida) is a useful food for the prevention of hyperphosphatemia in a rat model of renal failure. Feeding a diet containing 5% wakame significantly decreased plasma and urinary Pi levels and increased the amount of fecal Pi. In addition, wakame significantly reduced plasma blood urea nitrogen and plasma Pi levels in 5/6 nephrectomized rats fed a high-Pi diet. Biochemical analyses showed that the reduction of intestinal Pi absorption is the main reason for the decrease in plasma Pi levels in rats fed a diet containing wakame. In addition, feeding alginic acid and fucoidan, major components of wakame fiber, was effective in reducing plasma Pi levels in normal rats. Finally, we concluded that wakame may be a useful food for the prevention of hyperphosphatemia in rodents

コレステロール添加食投与ラットの肝脂肪蓄積に及ぼす焙煎度の異なるコーヒー豆抽出物の影響

We examined the effects of the extracts of coffee beans roasted at different degrees on the lipid metabolism of rats fed cholesterol（Cho）-added diets. Fatty livers along with a significant increase in triacylglycerol（TG）and Cho levels were observed in rats belonging to the C（Cho-added diet）group. Although the Cho level was slightly decreased in the S group, with the addition of shallow-roasted coffee bean extract to Cho-added diet, carnitine palmitoyltransferase activity showed a significantly high value, and the amount of TG was significantly reduced. In contrast, with the addition of deep-roasted coffee bean extract to Cho-added diet in the D group, fatty acid synthase activity showed a significantly lower value, TG and Cho levels were significantly reduced, and a reduction in fatty liver was observed. Moreover, since the levels of lipid peroxide in plasma and liver decreased in both S and D groups, compared to the Cgroup, there is a possibility that roasted coffee bean extracts may suppress the progression to nonalcoholicsteatohepatitis.原著論

ノシメマダラメイガのProteaseに及ぼすイネ種子糊粉層Trypsin Inhibitorの影響

イネ種子(Orayza sativa L.cv. Nihonbarre)中のtrypsin inbibitor(TI)の貯穀害虫であるノシメマダラメイガの腸内proteaseへの影響の検討を行った。試料には、5齢の幼虫全体を用い、リン酸ナトリウム緩衝液pH7.0でホモジナイズした上清を酵素液とした。イネ種子由来TIがtrypsinを約35%阻害するのと同じタンパク質量を酵素反応系に添加したところ、害虫酵素活性はTIによって約10%阻害され、メイガの消化液はserine protease単独ではないと考えられたため、幼虫酵素液のpHによる影響を検討した。活性のピークはpH3、6および9.5の3ケ所に認められ、どの群のproteaseかを特定することができなかった。次に各クラスを代表するprotease inhibitor存在下での幼虫酵素活性への影響を検討したところ、aspartic protease inhibitorで90%、cysteine protease inhibitorで10-30%活性が低下したが、metallo protease inhibitorでは活性は維持されたままであった。また、CaseinおよびBSAを基質に用い、pH3、6、8および9.5のbuffer中で一晩幼虫酵素液とともに反応させた。得られたペプチド断片を逆相HPLCにより分画し、それぞれの画分についてアミノ酸配列分析を行った結果と、既知のBSAアミノ酸配列から切断部位を推定した。切断部位のうち、pH3、6ではaspartic proteaseの反応部位と、pH8、9.5ではaspartic protease、cysteine protease、serine proteaseの反応部位と一致した。以上のことから、メイガ幼虫酵素液中には、aspartic proteaseが最も多く存在し、反対にmetallo proteaseは存在しないと考えられた。Caseinolytic activities in homogenates from the indian-mealmoth, P.interpunctella, were inhibited about 10% by trypsin inhibitor from rice aleurone, described earlier, which has a same dose of the ability to inhibit about 35% the activity of trypsin. Secondary, proteolytic activity in the extracts of the P.interpunctella decreased in the presence of commercially available protease inhibitors of each classes! Decreased 90% by aspartic protease inhibitor and 10 to 30% in cysteine protease inhibitor, however, was not inhibited by metallo protease inhibitor. Furthermore, the optimum pH\u27s of the protease of P.interpunctella were detected at pH 3,6 and 9.5. These results suggested that the digestive enzymes of the noxious insect may be consisted of a few classes of proteases. Casein or bovine serum albumin was digested by protease in four given pH, pH 3, 6, 8 and 9.5, respectively. Amino acid sequencis of the peptide fractions obtained from the digests by high-performance liquid chromatography, were analyzed. We considered that N-terminal amino acid of peptides fractionated were reactive sites of the midgut protease. From these results, it was confirmed that the cleaved sites were coincided with those of aspartic protease at pH 3 and 6 and with those of aspartic, cysteine and serine protease at pH 8 and 9.5. Consequently, the proportion of aspartic protease in the protease of P.interpunctella were high level, but metallo protease was not detected