Immunoassays for the quantitative determination of colchicine

A radioimmunoassay as well as an enzyme immunoassay for the quantitation of fmol amounts of the alkaloid colchicine have been developed. The antiserum used for both assays was raised against a conjugate of colchicoside-bovine serum albumin. The crude serum was satisfactory for the performance of the radioimmunoassay. For the enzyme immunoassay, the antibodies had to be isolated and purified by Rivanol treatment with subsequent (NH4)2SO4 precipitation. The measuring range extends from 0.1 to 100 ng colchicine for the radioimmunoassay and from 0.05 to 350 ng for the enzyme immunoassay with detection limits of 125 fmol and 25 fmol, respectively. Both immunoassays cross reacted with colchicoside and 3-demethyl-colchicine up to 80%. The colchicine content in the newly established suspension culture of Colchicum variegatum as well as the influence of various culture media on the colchicine production of this cell culture were investigated with the radioimmunoassay. The enzyme immunoassay was well suited for the quantitation of colchicine in HPLC fractions of Gloriosa and Colchicum seed extracts allowing the rapid, sensitive, and precise determination of the substance under investigation. The preliminary experiments indicate that both colchicine immunoassays can be a useful tool for the analysis of colchicine in tissue and cell culture studies, for analysis of plant extracts as well as for biosynthetic investigations.