Scopolamine radioimmunoassay for tissue cultures of Datura

A sensitive radioimmunoassay (RIA) has been established for investigation of scopolamine yields from cell and tissue cultures of Datura. A scopolamine-binding antiserum was obtained with a nor-(−)-scopolamine- N-propionic acid protein conjugate. The assay used commercially available labelled antigen, l-( N-methyl[ 3H])-scopol-amine methylchloride and measured scopolamine in the range 0.15 to 3.0 ng. The antiserum exhibited a cross-reactivity of 5.2% for hyoscyamine and 1.7% for 6-hydroxyhyoscyamine. Callus cultures of five species of Datura exhibited low levels of antigenic activity when assayed by RIA. Yields ranged from 3 ng to 4 μg scopolamine equivalents/g dry wt. Separation of a D. stramonium callus tissue extract by HPLC and analysis of the fractions by RIA gave tentative identification of scopolamine, 6-hydroxyhyoscyamine, norscopolamine and hyoscyamine as antigenic components of the extract. Hyoscyamine was found to be accumulated in excess of scopolamine and interfered in the specific determination of scopolamine in the unpurified extract.