Ajmaline, analysis

The spectroscopic data for a new alkaloid 8 (6) showed a similarity to those reported for anhydrovobasinediol (taberpsychine) (10) 11,12), but a significant NOE observed between H-19 and H-15 in the H-NMR spectrum of 8 suggested that the configuration of the ethylidene side chain was in the Z form. The C-NMR signal due to C-15 of 8 was observed downfield (7.0 ppm) and, in contrast, that of C-21 was observed upheld (6.9 ppm) compared to the corresponding signal of 10. The structure of 8 inferred by spectroscopic analysis to be 19(Z)-anhydrovobasinediol was confirmed by chemical synthesis from ajmaline (Section II.B). 

Arens et al. (691) reported a radioimmunoassay method for the quantitative analysis of ajmaline in plant material. Several plants were screened for their ajmaline content. The highest levels were found in R. vomitoria. Cell cultures of this plant were initiated and further optimized for ajmaline production. Tryptophan addition to the cell culture resulted only in one type of medium in an increase of alkaloid production (up to 0.04 g/liter). The RIA method also proved to be suitable in screening/ , serpentina cell clones for high production. Initial experiments showed variations in productivity over a factor 5 for cell clones obtained from one population. Cell line selection for improving alkaloid production thus seems promising. 

The relative stereochemistry of ajmaline has been confirmed by X-ray crystal structure analysis, but by the same method an effective anti-arrhythmic agent originally thought to be Af-n-propylisoajmalinium bromide has been shown to be X-n-propyl-21-ep/-isoajmalinium bromide. 

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