Phenylpropylamine
Phenylpropylamine, also known as 3-phenylpropylamine, is a monoamine releasing agent related to phenethylamine. It is the analogue of phenethylamine in which the ethylamine side chain has been lengthened by one carbon atom to instead be a propylamine chain.
Phenylpropylamine was synthesized and characterized during investigations of the structure–activity relationships of phenethylamine and amphetamine MRAs. It acts as a norepinephrine–dopamine releasing agent. However, phenylpropylamine is dramatically less potent than phenethylamine as an NDRA in rat brain synaptosomes in vitro and shows ~7-fold preference for induction of norepinephrine release over dopamine release.
The analogue of phenethylamine with the ethylamine side chain shortened by one carbon atom to instead be a methylamine chain is benzylamine. In contrast to phenethylamine and phenylpropylamine, benzylamine is said to be inactive as a norepinephrine releasing agent. However, certain derivatives of benzylamine have nonetheless been found to show MRA-like effects in animals. In addition, benzylpiperazine, an analogue of benzylamine with a methylamine-like side chain, is a potent MRA and psychostimulant.