Alkaloids of Carnegiea gigantea. Arizonine, a new tetrahydroisoquinoline alkaloid.

The alkaloid composition of the giant cactus, Carnegiea gigantea Br. & R., was studied. Chromatographic separation led to the isolation of four tetrahydroisoquinoline alkaloids: carnegine, salsolidine, gigantine and arizonine. The structure of the new natural product, arizonine, was establihsed by spectroscopic data and total synthesis via two independent routes. Salsolidine is reported for the first time in the cacti. Also new to this species are 3-methoxytyramine and 3,4-dimethoxypenethylamine, which were identified in the alkaloid extract by gas chromatography-mass spectrometry. Dopamine was isolated from fresh plant material.