Alkaloids are organic compounds, i.e., compounds based on carbon, which also contain at least one nitrogen atom. Alkaloids are frequently highly active physiologically in animals, and may cause death, nervous system intoxication, paralysis, and other effects related to poisoning. The alkaloids in P. harmala seeds are of two known types, both of which are highly physiologically active in animals and also in other plants of different genera that P. harmala contacts. Harmine is a classic fluorophore or fluorochrome, meaning it is a fluorescent compound, one whose aromatic structures, when excited by light, are able to re-emit light at characteristic frequencies usually different from the frequency of the light that caused the excitation. Precise targeting for an antitumor drug may be desirable, and modifications in the harmine structure have been achieved synthetically in order to increase the anticancer potency of harmine while simultaneously reducing its "neurotoxicity".