Definition: A group of ISOQUINOLINES in which the nitrogen containing ring is protonated. They derive from the non-enzymatic Pictet-Spengler condensation of CATECHOLAMINES with ALDEHYDES.
Other names Tetrahydro Isoquinolines; Tetrahydro-Isoquinolines; 1,2,3,4-Tetrahydroisoquinolines