Stem bark alkaloids of Rauvolfia caffra.

Thirty two alkaloids were isolated from the stem bark of Rauvolfia caffra and 28 were identified. The alkaloids represented corynane (3), strictamine (1), sarpagan (4), akuammicine (2), pleiocarpamine (1), indolenine (1), dihydroindole (6), peraksine (3), heteroyohimbine (2), hydroxyheteroyohimbine (2), oxindole (1), 2-acyl-indole (1), suaveoline (3) and yohimbine (2) types. The anhydronium base serpentine was detected but not isolated. The principal alkaloids were ajmaline and norajmaline (dihydroindoles), ajmalicinine and ajmalicine (heteroyohimbines), geissoschizol (E-seco indole) and pleiocarpamine and the heteroyohimbine derived alkaloids were predominantly normal configuration compounds. The biosynthetic and ethnopharmacological significance of the alkaloids is discussed.

Alkaloid distribution in some african rauvolfia species.

The distribution of indole alkaloids in the leaves, stems and roots of 10 African mainland RAUVOLFIA species is summarised and the interrelationships of the alkaloid types discussed.

Alkaloids of Rauwolfia caffra seeds.

Rauwolfia caffra seeds yielded 0.012 per cent total alkaloids comprising the sarpagan compound normacusine B, alpha-yohimbine, alloyohimbine, an incompletely characterised yohimbine and the principal alkaloid, yohimbine. Chromatographic evidence indicated traces of norajmalan and ajmalan compounds.

Stem bark alkaloids of Rauwolfia vomitoria.

Forty-three indole alkaloids were isolated from 7 kg Rauwolfia vomitoria stem bark; 39 were identified and 2 partially characterised. At least 72 alkaloids classified into 19 types occur in the plant and the interrelationship of the alkaloids and their distribution throughout the plant has been discussed. The major alkaloids of the stems were heteroyohimbines (especially reserpiline) and N (a)-demethyldihydroindoles.

The alkaloids of Rauwolfia volkensii.

The roots of Rauwolfia volkensii yielded 26 alkaloids comprising five main groups--sarpagan, akuammicine, heteroyohimbine with derived oxindole and anhydronium bases, yohimbine with 18-hydroxy-yohimbine and its derived esters, and dihydroindole alkaloids. The principal alkaloids were ajmaline (0.08 per cent) and reserpiline (0.15 per cent), and the reserpine yield (0.0007 per cent) was very low.