Abstract: | Cell-free systems from Catharanthus roseus plants are utilized for various studies relating to the biosynthesis of indole alkaloids. Tryptamine ( 5 ) and secologanin ( 6 ), two fundamental building units, are shown to be incorporated into the alkaloid vindoline ( 7 ). In another study, catharanthine ( 18 ) and vindoline ( 7 ) are utilized by this enzyme system and coupled to the important bisindole biointermediate 3′,4′-anhydrovinblastine 1 The previously [20] used name for 17 , 3′, 4′-dehydrovinblastine, is incorrect. ( 17 ). The latter substance is, in turn, incorporated and converted to the natural alkaloids leurosine ( 8 ), Catharine ( 9 ) and vinblastine ( 10 ), thereby providing information about the biosynthesis of these complex molecules. High pressure liquid chromatography assay of the enzymic mixture sheds light on the enzymes involved in the coupling of 18 and 7 . |