Intestinal absorption of serrapeptase (TSP) in rats.

A sensitive sandwich enzyme immunoassay (e.i.a.) for serrapeptase (TSP), an orally available anti-inflammatory proteinase, was established using affinity-purified anti-TSP rabbit IgG and its Fab' fragment conjugated with horseradish peroxidase as the first and the second antibodies respectively. TSP in the plasma was determined by the e.i.a. after its oral administration (100 mg/kg) to rats. The peak concentration was observed between 30 min and 2 h after administration. TSP in the plasma samples was trapped on a microtitre plate coated with the affinity-purified anti-TSP rabbit IgG, and the hydrolysis of a synthetic fluorogenic substrate, butoxycarbonyl-Glu(benzyloxy)-Ala-Arg-4-methylcoumaryl-7-amide, by the trapped TSP was fluorometrically measured (proteinase assay). The values obtained by the e.i.a. and those obtained by the proteinase assay correlated well for various plasma samples. These results indicate that orally administered TSP was absorbed from the intestinal tract and transferred into the circulation in an enzymically active form.