Alkaloids of Antizoma miersiana (Menispermaceae)

The main alkaloids of Antizoma miersiana and one of two species of the southern African endemic genus Antizoma (Menispermaceae), have been studied for the first time. Eight isoquinoline alkaloids could be positively identified (structural type in brackets): crotsparine (proaporphine); bulbocapnine and dicentrine (aporphine); cissacapine, cycleaneonine, cycleanine, insulanoline and insularine (bisbenzyltetrahydroisoquinoline). Crotsparine and bulbocapnine were the main alkaloids in the leaves, while bulbocapnine, dicentrine, insulanoline and an unidentified alkaloid are the major compounds in stems. The rhizome contains small amounts of all except crotsparine. There are clear differences, not only between various plant parts, but also between the two species of Antizoma. Bulbocapnine, for example, was previously found to be absent from the leaves and stems of Antizoma angustifolia. Dicentrine is absent from the latter and therefore appears to be of further diagnostic value to distinguish between the two species. The rich variety and yield of alkaloids in A. miersiana provide a rationale for its value as a medicinal plant.