https://doi.org/10.1351/goldbook.A00220
Basic nitrogen compounds (mostly heterocyclic) occurring mostly in the plant kingdom (but not excluding those of animal origin). Amino acids, @[email protected], @[email protected], @[email protected], @[email protected], @[email protected] and antibiotics are not normally regarded as alkaloids. By extension, certain neutral compounds biogenetically related to basic alkaloids are included.