Phenyl and phenylpropyl alkaloids

These alkaloids have a phenyl or phenylpropyl nucleus. The group includes simple phenyl amine (tyramine, hordenine), catecholamine (dopamine, noradrenaline, adrenaline), simple tetrahydroisoquinoline (mescaline, anhalamine, anhalonine, anhalonidine), benzylisoquinoline (e.g., papaverine), phthalideiso-quinoline (e.g., noscapine), phenethylisoquinoline (autumnaline, floramultine and kreysigine), tetrahydroisoquinoline (emehne and cephaeline) and terpenoid tetrahydroisoquinoline (secologanin and ipecoside) alkaloids. 

This structural group of indole alkaloids covers simple indole alkaloids (e.g., tryptamine, serotonin, psilocin and psilocybin), /3-carboline alkaloids (e.g., harmine), terpenoid indole (e.g., ajmalicine, catharanthine and tabersonine), quinoline alkaloids (e.g., quinine, quinidine and cinchonidine), pyrroloindole 

The a for the structural development of psilocin and psilocybin is L-tryptophan and the j3 is tryptamine. Psilocin is A and psilocybin is P. A and P are the main alkaloids in hallucinogenic mushrooms belonging to the genus Psilocybe. 

Carboline alkaloids, and especially /3-carbolines, are common in mammals . 

This group of alkaloids is very large and contains more than 3000 compounds. 

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Figure 63. Structural development of phenyl and phenylpropyl alkaloids.

Tyrosine is an important precursor of alkaloids with the phenyl and phenylpropyl nuclei. There are four basic alkaloid pathways. 

In the alkaloid synthesis, L-phenylalanine (Figure 30) provides to alkaloid the phenyl or phenylpropyl nucleus. These kinds of nuclei occur in cathionine, cathine, ephedrine, pseudoephedrine and norpseudoephedrine. Such alkaloids are found especially in many species of Ephedra. Natural alkaloid molecules from these plants have similar properties to synthetic compounds used as narcotics (e.g., amphetamine). 

L-tyrosine (Figure 2.11) is an aromatic amino acid (similar in compound to L-phenylalanine) that also provides phenyl (Figures 2.10 and 2.11) and phenylpropyl (Figures 2.10 and 2.11) nuclei for alkaloids. Molecules containing nuclei from L-tyrosine include, for example, mescaline, anhalamine, papaverine, curare, and morphine. They are biologically very strong natural compounds and occur relatively widely in the plant kingdom (Table 1.10). 

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