Antioxidant activities of abietane diterpenoids isolated from Torreya nucifera leaves.

Investigation on antioxidant compounds from the ethanolic extracts of Torreya nucifera leaves resulted in the isolation of abietane diterpenoids, a known 18-methylesterferruginol (1) and a new 18-dimethoxyferruginol (2). The structures of compounds 1 and 2 were elucidated on the basis of their spectroscopic analyses. Compounds 1 and 2 inhibited the Cu2+-mediated, 2,2'-azobis(2-amidinopropane)hydrochloride-mediated and 3-morpholinosydnonimine-1-mediated low-density lipoprotein (LDL) oxidation in the thiobarbituric acid-reactive substances assay as well as the macrophage-mediated LDL oxidation. Compounds 1 and 2 exhibited the potent antioxidant activities in the conjugated diene production, relative electrophoretic mobility, and apoB-100 fragmentation on copper-mediated LDL oxidation. Compound 1 also suppressed nitric oxide production and inducible nitric oxide synthase expression in lipopolysaccharide-stimulated RAW264.7 cells.