Antidepressant principles of the roots of Polygala tenuifolia

[I-125] RTI-55-membrane binding assay-guided fractionation and separation of a water-soluble extract of the roots of Polygala tenuifolia gave five new oligosaccharide derivatives, polygalatenosides A-E (1-5). The structures of these new oligosaccharides were established on the basis of spectroscopic evidence. Polygalatenosides A and B ( 1 and 2) showed significant inhibitory activity, with IC50 values of 30.0 and 6.04 mu M, respectively, in this membrane binding assay and acted as norepinephrine reuptake inhibitors through blocking norepinephrine transport.