N-Methylphenethylamine is a naturally occurring secondary amine neuromodulator and can be detected in human urine or plants[1].
[1]. P Marquardt, et al. N-Methylphenethylamine, an indirect sympathicomimetic agent in vegetables (author’s transl). Arzneimittelforschung. 1976;26(11):2001-3.
[2]. G B Neurath, et al.Primary and secondary amines in the human environment. Food Cosmet Toxicol. 1977 Aug;15(4):275-82.