In vitro binding of the carcinogen N-[methyl-¹⁴C]-nitrosodimethylamine by algal dietary fibers and their role in reducing its bioaccumulation

Abstract

The present study was initiated to determine if algal dietary fibers (DF) bind the carcinogen N-[methyl-¹⁴C]-nitrosodimethylamine (DMNA) in vitro and how bioaccumulation of orally-given carcinogen is affected by a diet containing algal DF. Eight kinds 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 or 24 h after dosing. There was reduced retention of the orally-ingested DMNA in the liver, possibly because of reduced DMNA-absorption 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.