Urinary metabolites of French maritime pine bark extract in humans.

After oral administration of 5.28 g and 1.06 g of French maritime pine bark extract to a human volunteer, metabolites of some of the components of the extract could be detected. Ferulic acid and taxifolin, conjugated as glucuronide/sulphate, were excreted within 18 h. The peak urinary excretion was observed approximately 2-3 h after intake. Recovery of ferulic acid in urine was 36-43% and 7-8% for taxifolin. Two further metabolites could be identified as delta-(3,4-dihydroxy-phenyl)-gamma-valerolactone and delta-(3-methoxy-4-hydroxyphenyl)-gamma-valerolactone conjugated with glucuronic acid/sulphate. These metabolites could also be detected after intake of 960 mg of a procyanidin fraction of French maritime pine bark extract. Thus, it was shown that procyanidins are metabolised by humans. Both metabolites show maximal urinary excretion 8-12 h after intake and are excreted within 28-34 h.