New xanthones from Canscora lucidissima and their antioxidant and NO inhibitory activities

Three new xanthone glycosides, canlucosides A - C (1 - 3), along with three known compounds (4 - 6), have been obtained and identified from the ethanol extract of Canscora lucidissima. Their structures were identified according to HR-ESI-MS, 1D, 2D NMR data, ECD measurements powered by molecular calculations and optical rotation values. Compound 6 (1-hydroxy-3,7,8-trmethoxyxanthone) was isolated from C. lucidissima for the first time. Five compounds (2-6) showed moderate antioxidant and NO inhibitory activities. Canlucosides B and C (2 and 3) showed significant antioxidant activity with IC50 values of 33.64 +/- 5.60 mu M and 36.63 +/- 4.32 mu M, respectively. Canlucoside B (2) possessed a significant NO inhibitory effect with an IC50 value 0.92 mu M.