Radioimmunoassays for the Determination of the Indole Alkaloids Ajmalicine and Serpentine in Plants1

A Radioimmunoassay was developed for the individual measurement of ajmalicine and serpentine in plant extracts. Each RIA was assessed for its sensitivity, specificity and accuracy. The preparation of antigens and antibodies specific for these alkaloids as well as the radiochemical preparation of ajmalicine– 3 H and serpentine– 3 H with high specific activities is described. The RIA method allowed the detection of 0.27 pmol (0.1 ng) ajmalicine and 1.4 pmol (0.5 ng) serpentine and has been successfully applied in the selection of individual plants with higher than average contents of these alkaloids for breeding and tissue culture purposes. Key Word Index Catharanthus roseus - Apocynaçeae - Radioimmunoassay - Indole Alkaloids - Distribution of Alkaloids - Screening Techniques