Pharmacological properties of some imidazole derivatives occurring in nature

Abstract

Abstract Some naturally occurring histamine derivatives such as monomethylhistamine [4-(2-methylaminoethyl)imidazole], dimethylhistamine [4-(2-dimethylaminoethyl)-imidazole], spinaceamine (4,5,6,7-tetrahydroimidazo[5,4-c]pyridine) and 6-methyl-spinaceamine, and the quaternary ammonium base of histamine [4-(2-trimethyl-aminoethyl)imidazole] hitherto unknown in nature, were submitted to a pharmacological examination. The actions of monomethylhistamine resembled closely those of histamine. Dimethylhistamine was 2 to 20 times less active than histamine and showed some weak “nicotinic” effects. Trimethylhistamine had about 1% of the activity of histamine but showed a potent “nicotinic” activity on the preparations examined. Spinaceamine and 6-methylspinaceamine were virtually inactive. The importance of the N‘-methylhistamines which behave similarly to the methyl derivatives of 5-hydroxytryptamine is discussed.