Pretazettine from Amaryllidaceae

Although tazettine (59) is one of the most widely distributed alkaloids in the Amaryllidaceae family, it was found to be an extraction artifact of pretazettine (61) (209). The presence of an A/-methyl group (2.4-2.5 ppm) in tazettine type alkaloids inmediately distinguishes them from the haemanthamine type, from which they proceed biosynthetically. Moreover the H NMR spectrum always shows the signal corresponding to the methylenedioxy group. 

Tazettine (62) is a widely reported alkaloid in the Amaryllidaceae family, particularly in Narcissus (see Tables VIII and IX), although it is known to be an extraction artifact of pretazettine (64) (75). All the alkaloids of the tazettine type that are isolated from Narcissus species show the typical methylenedioxy group between the C-8 and C-9 positions. Obesine (67) is an exceptional tazettine-type alkaloid with a seven-membered ring 76). 

Although tazettine (62) is one of the most widely reported alkaloids in the Amaryllidaceae family, it was found to be an extraction artifact from pretazettine (64) (75). 

A number of Amaryllidaceae alkaloids are of interest as potential antitumor agents. The most important are lycorine (8), narciclasine (22), and pretazettine (15). Lycorine is widely distributed in the family and is known from at least 30 genera. Pretazettine is not so widely distributed but is found in at least 18 genera. Narciclasine (22) is known from only a few species of the family (Martin, 1987 Suffiiess and Cordell, 1985). 

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