Yuan Zhi is used mainly as an expectorant. It is one of the 50 root herbs used in traditional where it is called yuan zhi.
A randomized, double-blind, placebo-controlled, parallel-group study of the extract of dried roots of Polygala tenuifolia in healthy adults produced memory-effects effects. A similar trial with elderly people also significant significant improvement P. tenuifolia increases NGF secretion in astrocytes.
cognition improving, neuroprotective and antidepressant effect.
Preclinically, Radix Polygalae extract has been

shown to demonstrate a rapid-onset antidepressant-like effect. One triterpenoid saponin from the roots, Yuanzhi-1, shows significant-ity to 5-HT, NE and DA transporters and potent antidepressant-like effects.
3,6'-disinapoyl sucrose from Polygala tenuifolia significantly inhibited MAO-A and MAO-B activity, blocked stress-induced elevations of plasma cortisol, improved hippocampal-dependent learning and memory and rescued stress-induced deficits in hippocampal neuronal plasticity and neurogenesis.
Radix Polygalae extract also showed anti-inflammatory activity towards microglia.