Alkaloids Derived from Phenylalanine and Tyrosine

A very large number of alkaloid structures arise from the metabolism of aromatic amino acids (phenylalanine, tyrosine), and at first approximation, these are always isoquinoline alkaloids.
Isoquinolone alkaloids
The isoquinolone structure occurs in considerable number of alkaloids in widely separated families. They represent the largest single group of plant alkaloids, and there is a great variation in their chemical structures. Some of the important isoquinlone subgroups are benzylisoquinolone represented by papaverine and tubocurarine, the benzophenanthridines represented by saguinarine, the pthalideisoquinolone that contain a?- lactone ring and are represented by hydrastine, the morphinans represented by opium alkaloids, the protoberberines represented by by berberine , and those with emetine skeleton
Tubocurare and d- tubocurarine:-
Curare or south American arrow poison is a crude extract from the bark of Chondodendron tomentosum and C. platyphyllum (Menispermaceae), which grow wild in Brazil. The poisonous material is known as curare (which means “poison” in several local languages). The toxic principle is the biscoclaurine-type alkaloid d-tubocurarine an alkaloid derived from phenylalanine. The chemical structure of d-tubocurarine was first proposed as a bisbenzylisoquinoline with two quaternary ammonium moieties.