The role of rutin and quercitrin in stimulating flavonol glycosidase activity by cultured cell-free microbial preparations of human feces and saliva.

The non-mutagenic flavonol glycosides, rutin and quercitrin, are hydrolysed by cell-free extracts of human fecal cultures to the mutagenic product, quercetin, detectable in the Ames test and by thin-layer chromatography. Cell-free extracts of human saliva cultures hydrolyse rutin but not quercitrin. The pH optima for rutin glycosidase is 7.0 and for quercitrin glycosidase, 5.0. These findings indicate that (a) the bulk of the glycosidase activity in cell-free preparations of fecal and salivary cultures is 'inducible'; (b) the two glycosidases are distinctly different; (c) they are produced by different organisms; and (d) both types of organisms are present in feces while only the rutin-glycosidase-elaborating organisms occur in saliva.