Voacanga africana isolated alkaloids

Isolation of the stereospecific strictosidine s)mthase (STS) and formation of strictosidine with the 3a-(S) configuration proved conclusively that this was the natural precursor of the terpenoid indole alkaloids. Strictosidine occurs naturally in Rhazya stricta and the synthase has been isolated from a number of other species Amsonia salicifolia, A. tabemaemontam, Catharanthus pusillus, C. roseus, Rauvolfia verticillata, R. vomitoria, R. serpentina, Rhazya orientalis and Voacanga africana. The enzyme has been purified to homogeneity from R. serpentina (Hampp and Zenk, 1988). A comparison of the activity of STS from C. roseus roots, the only portion of the plant to contain ajmalicine, with that present in plant cell cultures producing the same alkaloid demonstrated that the plant cell cultures are far more metabolically active (Ziegler and Facchini, 2008). 

A pentacyclic alkaloid, so far unnamed, isolated (90) from the leaves of Voacanga africana Stapf, is the epoxide 75 of a degraded aspidospermane base in which C-5 and C-6 of the original tryptamine ethanamine chain have been lost this is the first recorded occurrence of this ring system. 

A number of new alkaloids are closely related to vobtusine. These include vobtusine lactone (alkaloid V) and desoxyvobtusine lactone (alkaloid IV) from Voacanga africana Stapf. and desoxyvobtusine, voafoline (alkaloid VII), isovoafoline, voafolidine (alkaloid IX), and folicangine (alkaloid VIII) from the same plant. From Callichilia (Hedranthera) barteri (Hook.f.) Pichon owerreine, goziline (= desoxyvobtusine ), and amataine have been isolated. 

Numerous alkaloids have been isolated from Voacanga africana Stapf., and Poisson and co-workers (85) have reported on two new compounds having the quebrachamine skeleton. 

In the past decades, many stndies were condncted and reported that focused on the identification of the wide array of V. africana alkaloids and the main ergot alkaloids have been isolated. With the improvement of the isolation procedures many minor components have been identified (Table IV). Voacanga alkaloids have been isolated from leaves, seeds (mature and inmature), tmnk and root bark (Table IV). 

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