Intestinal Absorption and Tissue Distribution of [14C]Pyrroloquinoline Quinone in Mice:

AbstractPyrroloquinoline quinone (PQQ) functions as a cofactor for prokaryotic oxido-reductases, such as methanol dehydrogenase and membrane-bound glucose dehydrogenase. In animals fed chemically defined diets, PQQ improves reproductive outcome and neonatal growth. Consequently, the present study was undertaken to determine the extent to which PQQ is absorbed by the intestine, its tissue distribution, and route of excretion. About 28 μg of PQQ (0.42 μCi/μmol), labeled with 14C derived from l-tyrosine, was administered orally to Swiss-Webster mice (18–20 g) to estimate absorption. PQQ was readily absorbed (62%, range 19–89%) in the lower intestine, and was excreted by the kidneys (81% of the absorbed dose) within 24 hr. The only tissues that retained significant amounts of [14C]PQQ at 24 hr were skin and kidney. For kidney, it was assumed that retention of [14C]PQQ represented primarily PQQ destined for excretion. For skin, the concentration of [14C]PQQ increased from 0.3% of the absorbed dose at 6 hr to 1...