3-Hydroxy-4-methoxycinnamic acid, predominantly trans is available as white crystals. 3-Hydroxy-4-methoxycinnamic acid is isolated from the aerial part of Artemisia capillaris, Chinese medicinal plant. It is a component of chinese herbal medicine used for a pain killer and stomachic. It is an efficient acetylcholine inhibitor. 3-Hydroxy-4-methoxycinnamic acid is bioactive metabolite of Spilanthes acmella Murr. It increases the resistance of low-density lipoprotein (LDL) to oxidation.