BETA-GLUCOSIDASE ACTIVITY IN THE RAT SMALL-INTESTINE TOWARD QUERCETINMONOGLUCOSIDES

In order to evaluate the positional specificity for a glucoside group in the hydrolysis of flavonoid glucosides in the rat small intestine, beta-glucosidase activity was measured with the quercetin monoglucosid es, quercetin-3-O-beta-D-glucopyranoside (Q3G), quercetin-4'-O-beta-D- glucopyranoside (Q4'G) and quercetin-7-O-beta-D-glucopyranoside (Q7G), as well as with quercetin-3-O-rutinoside (rutin) and p-nitrophenyl-be ta-D-glucopyranoside (NPG) by using the HPLC technique. Enzymes were p repared from rat small intestinal mucosa of the duodenum, jejunum and ileum, among which the enzyme activity of the Jejunum was highest for all the glycosides tested. Q4'G was the richest substrate for a beta-g lucosidase solution among these glycosides, while rutin and NPG were b oth poor substrates. This suggests that dietary flavonoid glucosides a re primarily hydrolyzed and liberated aglycones in the jejunum.