1993 Fiscal Year Final Research Report Summary
In vitro binding of the carcinogen N-[methyl-^<14>C]-nitrosodimethylamine by algal dietary fibers and their role in reducing its bioaccumulation.
| Project/Area Number |
04671397
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
医学一般
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| Research Institution | Kitasato University School of Hygienic Sciences |
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Principal Investigator |
YAMAMOTO Ichiro Kitasato University School of Hygienic Sciences Professor, 衛生学部, 教授 (10050361)
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| Co-Investigator(Kenkyū-buntansha) |
MARUYAMA Hiroko Kitasato University School of Hygienic Sciences Lecturer, 衛生学部, 講師 (50129269)
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| Project Period (FY) |
1992 – 1993
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| Keywords | algal dietary fiber / binding of carcinogen / cellulose / polydextrose / bioaccumulation / radio-labeled carcinogen / N-[methyl-^<14>C]-nitrosodimethylamine |
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| Research Abstract |
The first study was initiated to determine if algal dietary fibers (DF) bind the carcinogen N-[methyl-^<14>C]-nitrosodimethylamine ([^<14>C]-DMNA) in vitro and how bioaccumulation of orally-given carcinogen is affected by a diet containing algal DF.Eight kineds of algal DF, including powdered fronds of Laminaria religiosa (LRP) and agar (from Gracilaria verrucosa) were used in the in vitro test. Cellulose powder (CP) was used as a control DF.In vitro binding rates of DMNA by CP, LRP and agar were 0.28%, 0.65% and 0.21% of the initial dose, respectively. Rats fed a diet containing 2% LRP or 2% agar were examined at 3 h or 24 h after dosing. There was reduced retention of the orally-ingested DMNA in the liver, posibly because of reduced DMNA-adsorption from the intestinal tract earlier than 3 h after dosing. Binding rates of DMNA by algae were neither related to the DF values nor to the extent of reduction of DMNA-absorption from the intestinal tract.
The second study was performed to verify the effects of cellulose (nsoluble in water) and of polydextrose (soluble in water), in reducing bioaccumulation of the carcinogen [^<14>C]-DMNA in the same in vivo experimental system, using mice. As the results, [^<14>C]-bioaccumelation in CP-fed mice remarkably reduced at 1 h after dosing, compared with that in control mice.
In the time points later than 1 h after dosing, difference in the bioaccumulation between CP-fed mice and cntrols were decreased sowly as the time lapsed. The results suggest that absorption and metabolism of the carcinogen took lace within 1 h after dosing. As to polydextrosefed mice, there was no significant reductin of [^<14>C] uptake, except blood at 24 h after dosing.
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