Sources and pharmacology
Palmatine, along with Berberine and a few others, are compounds known as 'Protoberberine alkaloids' found in various plant species.
Palmatine has been shown to enhance the efficacy of Nerve Growth Factor (NGF) in neurons, by increasing the output of neurite from PC12 neurons exposed to an NGF stimuli. These effects were also seen with Berberine and coptisine, with berberine being more effective than coptisine being more effective than palmatine. Protoberberine compounds also suppress catecholamine synthesis in neurons with palmatine having a lower IC50 value. These suppressive effects are more potent with palmatine, and at least in regards to dopamine are not seen with coptisine. These effects were seen through direction inhibition of the tyrosine hydroxylase enzyme.