Antioxidant Constituents from the Leaves ofCedrela sinensis A. Juss

Phytochemical study on the EtOAc fraction from the MeOH extract of the leaves of Cedrela sinensis led to the isolation of five known phenolic compounds (1-5), whose structures were identified as (+)-catechin (1), kaempferol-3-O-α-Lrhamnopyranoside (2), quercetin (3), quercetin-3-O-α-L-rhamnopyranoside (4), and quercetin-3-O-β-D-glucopyranoside (5), respectively, by comparing their spectral (UV, IR, 1H and 13C-NMR, and ESI-MS) and physicochemical data with those reported in the literature. Among the isolated compounds (1-5), compounds 1 and 3-5 exhibited significant DPPH radical scavenging effects with IC50 values ranging from 21.3 ± 1.4 to 38.1 ± 3.2 μM as well as superoxide anion radical scavenging effects with IC50 values ranging from 9.4 ± 0.7 to 21.2 ± 3.6 μM. Furthermore, compounds 1 and 3-5 also exhibited considerable inhibitory effects on LDL peroxidation induced by either Cu2+ or AAPH with IC50 values ranging from 1.4 ± 0.4 to 11.9 ± 1.4 μM. These results indicated that flavonoids are the major constituents of C. sinensis and considered to be antioxidant principles of this plant.