Cynanchum vincetoxicum

Cynanchum vincetoxicum (L.) Pers. contains traces of an alkaloid vincetene, which shows an interesting relationship to the phenanthroindolizidines found in Tylophora and other genera of the Asclepiadaceae. Spectroscopic study has shown vincetene to be the benzopyrroloisoquinoline derivative (2), and this structure has been confirmed by synthesis of the racemic dihydro-desoxy-deriva-tive (3).2... 

From Cynanchum vincetoxicum (L.) Pers., a new base, vincetene, which is a benzopyrroloisoquinoline, has been isolated.22... 

Ficuseptinc A-D Fiscus septica Cynanchum vincetoxicum Fiscus septica Moraceae ... 

The aerial parts of Cynanchum vincetoxicum (L.) Pers. (Asclepiadaceae) contain three phenanthroindolizidine alkaloids, which have been shown to be tylophorine (34), 7-demethoxytylophorine (Alkaloid A, 35), and 7-demethoxy-demethyltylophorine (Alkaloid C, 36). The trimethoxy-base (35) has also been isolated, together with two unidentified alkaloids, from the dried roots of the same plant,and from Vincetoxicum officinale Moench., in which it occurs along with tylophorine. The early work on this trimethoxy-base indicated that it was either (35) or the 3,6,7-trimethoxy isomer, but this latter possibility has now been excluded. The n.m.r. spectrum did not allow a distinction to be made between (35) and the 3,6,7-trimethoxy analogue, hence the alkaloid was oxidised by mercuric acetate, and the immonium salt so obtained was... 

Tylophora asthmatica, Cynanchum vincetoxkum, Pergularia pallida, Vincetoxicum officinale (Asclepiadaceae), Ficus septica (Moraceae)... 

Tylophorine (1) and its analogs, the phenanthroindolizidine alkaloids also referred to as tylophora alkaloids, have been isolated primarily from plants of the family Asclepiadaceae [13-16], Fig. (1), including members of the genus Tylophora, Vincetoxicum, Pergularia, Cynanchum, but also from Hypoestes verticillaris (Acanthaceae) [17], Cryptocarya phyllostemmon (Lauraceae) [18], Ficus hispida and F. septica (Moraceae) [2, 19]. TTie isolations of these alkaloids are summarized in Table 1. The most significant phenanthroindolizidine alkaloids are tylophorine (1), tylocrebrine (2), antofine (3), and tylophorinine (4), Fig. (2). 

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