Ferulic acid excretion as a marker of consumption of a French maritime pine (Pinus maritima) bark extract

French maritime pine (Pinus maritima) barb extract (PBE) is a polyphenol-ri ch food supplement patented under the name of Pycnogenol and known to have strong antioxidant activity and different beneficial effects on human healt h. Although its biological properties have begun to be extensively studied both in vitro, in laboratory animals and more recently in humans, little is known about its bioavailability. The present study investigated the urinar y excretion of free and conjugated ferulic acid, present in quantitatively detectable amounts in PBE, after oral PBE administration to human subjects. Eleven healthy adult subjects (4 women and 7 men) consumed either a single dose (200 mg PBE) or two doses of PBE (100 and 200 mg, respectively) withi n a 48-h interval. Two days before the oral administration of PBE and durin g the urine sample collection period volunteers adhered to a diet low in po lyphenols. Aliquots of all urine production were collected over 24 h. Free and conjugated ferulic acid was assessed in urine by HPLC using diode array detection. A close association between the dietary intake of PBE and the u rinary excretion of ferulic acid was detected. Moreover, the results indica te that a considerable proportion of ferulic acid is excreted as glucuronid e or sulfate after PBE consumption, varying over the range 2 to 20% between individuals. The kinetics of excretion associated with the administration of 100 mg PBE was quite similar to that obtained after 200 mg PBE. A a biph asic trend was evident in a number of subjects. All subjects studied here d isplayed a significant, although Variable level of excretion of ferulic aci d after supplementation with PBE, Thus, the data provide evidence that at l east a part of the phenolic components of PBE are absorbed, metabolized, an d eliminated by humans. (C) 2000 Elsevier Science Inc.