3,4,5-trimethoxycinnamic acid, aka sinapinic acid methyl ether, is a naturally occurring derivative of cinnamic acid. It is very closely related in structure to sinapinic acid, ferulic acid, and caffeic acid. It is also a major metabolite of elemicin. The acute toxicity of this compound is extremely low, with comparable LD50/toxicity values to ferulic acid and sinapinic acid, both of which are non-toxic nutrients and fundamental building blocks for lignins (the fundamental structural component of wood and plant fibers). Along with other cinnamic acid derivatives, it is found ubiquitously in all organisms in the plant kingdom.
3,4,5-trimethoxycinnamic acid has been isolated from Polygala tenuifolia, a Chinese traditional medicine used sometimes as a nutritional supplement or nootropic.In mice studies it has GABAergic effects, as a positive allosteric modulator . This indicates possible anxiolytic, antidepressant, and neuroprotective activity.
Cinnamic acid and its derivatives (such as phenyl ring substituted analogs) can undergo electrolytic amination to form the L-phenylalanine derivatives . One study found that caffeic acid (3,4-dihydroxycinnamic acid) can be aminated in an electrode cell to form L-DOPA (3,4-dihydroxyphenylalanine). This can be further decarboxylated (simply by boiling the precursor in anhydrous solvent) to form dopamine (3,4-dihydroxyphenethylamine).
This means that substituted analogs of cinnamic acid (such as ferulic acid and sinapinic acid) can be used as precursors to the corresponding ring-substituted phenylalanines (e.g. 3-methoxy-4-hydroxy-L-phenylalanine, 3,5-dimethoxy-4-hydroxy-L-phenylalanine, etc).
Available as the free acid, and trans isomer only.