Biosynthetic studies of the antitumor ecteinascidins in the marine tunicate Ecteinascidia turbinata

Ecteinascidin is a tetrahydroisoquinoline alkaloid isolated from the colonial ascidian Ecteinascidia turbinata. Ecteinascidin exhibits tremendous activity against P388 murine leukemia, however its yields from the tunicate are as low as 10^-4%. A biosynthetic investigation, using in vivo and in vitro methods, has resulted in the identification of the metabolic precursors of ecteinascidin as tyrosine, DOPA and cysteine. Reactive intermediates such as tyrosine and DOPA diketopiperazines have also been identified. These preliminary experiments set the stage for subsequent protein isolation.