Kucukboyaci_2010_Z.Naturforsch.C_65_187

Phytochemical investigations of Taxus baccata L. by successive chromatographic methods resulted in the isolation of the lignans lariciresinol (1), taxiresinol (2), 3'-demethylisolariciresinol-9'-hydroxyisopropylether (3), isolariciresinol (4), and 3-demethylisolariciresinol (5) as well as taxoids. Compounds 1-5 were evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and lipoxygenase (LOX) inhibitory activities, which play a role in the pathogenesis of Alzheimer's disease (AD), by in vitro spectrophotometric methods, while they were also screened for their antioxidant capacity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferrous ion-chelating effect, and ferric-reducing antioxidant power (FRAP) at 125, 250, 500, and 1000 microg ml(-1). All compounds exhibited a moderate inhibition against both BChE and LOX, whereas they were inactive towards AChE. The compounds displayed a great scavenging activity against DPPH especially at 500 and 1000 microg ml(-1). Besides, they were found to exert noteworthy reducing antioxidant power on ferric ions. In particular, the FRAP of compounds 2 (3.552 +/- 0.02), 4 (3.021 +/- 0.71), and 5 (3.533 +/- 0.01) were as high as that of the reference chlorogenic acid (3.618 +/- 0.01) at 1000 microg ml(-1). None of the compounds exhibited chelating ability against ferrous ions.