2-Phenethylamine alkaloids

The family Celastraceae consists of about 50 genera and 800 species of trees, shrubs, or climbers known to produce a series of phenethylamine alkaloids that might hold some potentials as sources of dopaminergic agents. About 30 plant species of Celastraceae are medicinal in the Asia-Pacific region. 

Since a-amino-acids serve as starting materials for the synthesis of protein and the elaboration of many plant alkaloids, there must be a sharing of any amino-acid which is required for both of these activities. The extent to which this happens has been the subject of a new study in one particular plant, Lophophora williamsii, which produces isoquinoline and j8-phenethylamine alkaloids. These bases are derived from the a-amino-acid tyrosine and the results from feeding L-[f/- C]tyrosine indicate that this amino-acid is incorporated into the alkaloids approximately three times more efficiently than into protein. Only the L-isomer was examined and one wonders what the results with D-tyrosine would be in the light of the known preference for particular optical isomers of lysine in pipecolic acid and piperidine alkaloid biosynthesis. 

Homemann, K.M.K. etai 1973. Cactus alkaloidsxii. p-Phenethylamine alkaloids of the genus Coryphantha Journal of Pharmaceutical Sciences 61 41—45. 

Results of isolation and structural elucidation work on ) -phenethylamine alkaloids are recorded in Table 2. The investigation of Aegle marmelos, a medicinal plant of India, revealed the presence of the amide alkaloid tembamide. ... 

This cactus is an important source of the so-called phenylethylamine (phenethylamine) alkaloids with a C6C2N skeleton.The main component... 

A recent paper by Schroeder and Stermitz on isopentenyl substituted 2-phenethylamine alkaloids aids greatly in resolving some of these question. These workers found a series of four racemic alkaloids in a Zanthoxylium species. These alkaloids are all formal Diels-Alder adducts in which addition has occurred in a fashion (Fig. 2) entirely different from that found in the coumarin dimers (Fig. 1). 

Synthetic work directed towards the preparation of these 2-phenethylamine alkaloids led to structural analogues of the coumarin dimers. Thus, when the isopentendienyl hordenine (15) was allowed to stand at room temperature, both diastereoisomers 16 and 17 were formed in a 9 1 ratio. 

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