3,4,5-Trimethoxycinnamic acid is a phenylpropanoid isolated from the roots of Polygala tenuifolia
WILLD, with anti-stress effect, prolonging the sleeping time in animals. 3,4,5-Trimethoxycinnamic acid increases expression of GAD65 and γ-subunit of GABAA receptor, but shows no effect on the amounts of α-, β-subunits.