OBJECTIVETo study the antioxidant constituents from the roots of Securidaca inappendiculata.

METHODThe bioassay-guided isolation of antioxidant constituents was carried out by the column chromatographic techniques. The combination of IR, MS, NMR and 2D-NMR spectroscopics methods was used to identify their structures.

RESULTTwo new xanthones, 1, 2, 5-trihydroxy-6, 8-dimethoxy-9H-xanthen-9-one(1), 1, 5-dihydroxy-2, 6, 8-trimethoxy-9H-xanthen-9-one (2), along with seven known ones, 3, 8-dihydroxy-1, 4-dimethoxy-9H-xanthen-9-one(3), 4, 6-dihydroxy-1, 5, 7-trimethoxy-9H-xanthen-9-one(4), 7-hydroxy-1, 2, 3, 8-tetramethoxy-9H-xanthen- 9-one(5), 1, 7-dihydroxy-9H-xanthen-9-one(6), 4-hydroxy-3, 7-dimethoxy-9H-xanthen-9-one(7), 1,7-dimethoxy-9H-xanthen-9-one(8) and aucuparin(9), were isolated from the roots of S. inappendiculata.

CONCLUSIONCompounds 1 and 2 were new xanthones, and compound 3 was isolated as a natural product for the first time, and compounds 4 and 6 were isolated for the first time from this genus. The antioxidant activities of all compounds were evaluated by ABTS, FRAP and DPPH assays respectively. Compound 9 showed significant activity by the ABTS and FRAP assays. Compound 1 showed significant activity with IC50 value of 0.31 mg x L(-1) in DPPH assay. Scavenging capacity of all compounds determined by all assays were well correlated between ABTS and FRAP assay (r = 0.9555).