Pharmacokinetic characterization of decursinol derived from Angelica gigas Nakai in rats.

Decursinol is a major coumarin derived from the roots of Angelica gigas and has various pharmacological effects against inflammation, angiogenesis, nociceptive pain and Alzheimer's disease. In vitro and in vivo studies were conducted to characterize the metabolism and pharmacokinetics of decursinol. Decursinol exhibited high stability to oxidative and glucuronic metabolism in human and rat liver microsomes. In Caco-2 cell monolayers, decursinol showed high permeability (>14 × 10(-6) cm/s) at all tested concentrations in the absorptive direction, which saturated at 100 μM. Secretion increased in a concentration-dependent manner, with an efflux ratio of more than 2 at 50 μM, indicating the participation of an active efflux transporter such as P-glycoprotein, multidrug resistance protein 2 or breast cancer resistance protein. The fraction of decursinol not bound to plasma proteins was 25-26% in the rat and 9-18% in humans. In human plasma, but not rat plasma, the percentage of unbound decursinol was concentration dependent. Following intravenous administration in rats, non-linear elimination of decursinol was observed with K(m) and V(max) values of 2.1 μg/mL and 2.5 mg·h(-1)·kg(-1), respectively. Following oral administration, decursinol exhibited high oral bioavailability (>45%) and rapid absorption (T(max), 0.4-0.9 h) over the dose range studied. In addition, dose-dependent absorption and elimination were observed at 20 mg/kg.