| Project/Area Number |
12660120
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
食品科学・栄養科学
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| Research Institution | Kyoto Prefectural University |
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Principal Investigator |
KANAMOTO Ryuhei Kyoto Prefectural University, Department of agriculture, Associate Professor, 農学部, 助教授 (70147297)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Kenji Kyoto Prefectural University, Faculty of Human environment, Associate Professor, 人間環境学部, 助教授 (00202094)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | resistant protein / sitybean protein / anti carcinogenic food / bile acid / enterrohepatic circulation / rat / colon cancer / hepatic cancer |
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| Research Abstract |
UDF is a residue remained after digestion of soy protein isolate by bacterial protease. We found that feeding of UDF to the rat effectively suppressed colon and liver carcinogenesis induced by bile acids. In the rat fed UDF, the serum concentration of bile acid was reduced conomitantly with the increase of fecal bile acids excretion. There found a god correlation among the excretion of fecal nitrogen, amino acid, bile acid and cholesterol. This suggested that indigestible peptide, as we call a "resistant protein" may derived form UDF capture bile acids in the intestine and stimulate their excretion. This could disrupt micelle formation of cholesterol with bile acids and interrupt cholesterol absorption. To prove the existence of such resistant protein, we tried to extract the peptide from feces. However, most of them were not extracted by the solvent such as guanidine and urea containing buffer and remained in the insoluble fraction. The insoluble fraction contained much hydrophobic amino acids than UDF itself and showed strong bile acid-binding ability. Bile acids in the feces could not be extracted by phosphate buffer but by 75 % EtOH. Therefore, it is suggested that bile acids were captured in the resistant protein by hydrophobic binding and excreted into the feces as the insoluble fraction. The promoter activity of bile acids in the colon might be suppressed by the formation of complex with the resistant protein. By digestion of UDF by pepsin followed pancreation in vitro, we obtained residual fraction of UDF (RF-UDF) in the yield of 30 %. The bile acid binding ability of RF-UDF in vitro was two-fold higher than that of UDF and 10 % of RF-UDF in the diet is as enough as 20 % UDF diet to excrete bile acid into feces. RF-UDF contained more hydrophobic amino acids than UDF and its amino acid composition was very similar to fecal amino acid composition of rat fed either UDF or R-UDF to the food staff is now progressing.
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