METABOLIC DISPOSITION IN RATS OF REGULAR AND ENZYMATICALLY DEPOLYMERIZED SODIUM CARBOXYMETHYLCELLULOSE

Partially enzyme-hydrolysed sodium carboxymethylcellulose (CMC-ENZ), w hich holds promise as a new, functional food ingredient, is obtained f rom sodium carboxymethylcellulose (CMC) by enzymatic hydrolysis with a cellulase preparation from Trichoderma longibrachiatum. In the safety evaluation of CMC-ENZ, a comparative disposition study on C-14-labell ed CMC and CMC-ENZ was conducted in conventionally kept rats. The C-14 label was in the two C atoms of the carboxymethyl group. Two groups o f four male and four female rats each were fed diets with 5% unlabelle d CMC or CMC-ENZ for a 2-wk adaptation period. A single oral dose of C -14-CMC or C-14-CMC-ENZ solution was then given by gavage (500 mg/kg b ody weight). Respiratory CO2, urine and faeces were collected at regul ar intervals, and after 120 hr organs, tissues and the carcass were sa mpled as well. For both experimental groups, total mean recovery of C- 14 was 98%, about 95% of the label being excreted with the faeces, 2% or less in the urine, 1% or less with CO2 and a small fraction being r etained in the body (CMC, 0.58%; CMC-ENZ, 0.75%). Tissue retention of C-14 was highest in the liver of rats of both experimental groups. Onl y about 49 and 65% of the faecal C-14 was extracted with water in the C-14-CMC and C-14-CMC-ENZ dosed rats, respectively. Gel permeation chr omatography (GPC) of the dosing solutions and the faecal extracts reve aled that CMC is depolymerized during intestinal passage whereas CMC-E NZ is excreted nearly unchanged. Consequently, the molecular weight di stribution of the C-14-CMC and C-14-CMC-ENZ faecal excretion products was similar. It is concluded that there is no toxicologically relevant difference between the disposition of CMC and CMC-ENZ.