AN ASSAY FOR SECOLOGANIN IN PLANT-TISSUES BASED ON ENZYMATIC CONVERSION INTO STRICTOSIDINE

The secoiridoid glucoside secologanin is the terpenoid building block in the biosynthesis of terpenoid indole alkaloids. A method for its de termination in plant tissues and in cell suspension cultures has been developed. This assay is based on the condensation of secologanin with tryptamine, yielding strictosidine, in a reaction catalysed by the en zyme strictosidine synthase (STR; E.C. 4.3.3.2). Subsequently, the for mation of strictosidine is quantified by high performance liquid chrom atography (HPLC). STR was isolated from transgenic Nicotiana tabacum c ells expressing a cDNA-derived gene coding for STR from Catharanthus r oseus. The high specificity of STR for secologanin, in combination vii th a sensitive and selective HPLC system, allows a simple extraction o f secologanin from plant tissue. The detection limit of this method is 15 ng secologanin. Using this assay, secologanin contents were determ ined in tissues of various plant species; Lonicera xylosteum hairy roo ts were found to contain 1% of secologanin on a dry weight basis. (C) 1998 John Wiley & Sons, Ltd.