Radioimmunoassay for the Quantitative Determination of Ajmaline

Abstract

A radioimmunoassay for the determination of pmol amounts of the indole alkaloid ajmaline has been developed. The antiserum was raised against a conjugate of ajmaline hemisuccinate-bovine serum albumine. The measuring range of the assay extends from 0.05 to 20 ng of ajmaline, and as little as 150 fmol may be detected. The antiserum is highlyspecific for ajmaline, with only the ajmaline-isomers sandwicine, isoajmaline, and the unnatural 17-monochloroacetylajmaline showing substantial cross reactivity. This assay allowsthe rapid, sensitive and precise determination of ajmaline in unpurified extracts of whole plants as well as of cell cultures. The distribution of ajmaline in Rauwolfia plants, as well as the ajmaline production of Rauwolfia cell cultures, has been investigated. The assay was used for studies to improve the Rauwolfia cell culture medium and a preliminary survey on the variability of ajmaline production in a population of Rauwsolfia cells is given.