Estimation of <i>S</i>‐methylcysteine sulphoxide (kale anaemia factor) and its distribution among brassica forage and root crops

Abstract

Abstract S ‐methylcysteine sulphoxide (SMCO), kale anaemia factor, was quantitatively extracted from a variety of brassica crops by repeated maceration in water. It was separated from other components of the deproteinised extract by electrophoresis on silica gel impregnated glass‐fibre sheet; and after visualising with ninhydrin/cadmium acetate reagent, the SMCO spots were quantitated by reflectance‐mode densitometry. Values for SMCO contents of plants thus obtained agreed well with those obtained by ion‐exchange chromatography. The method is useful for rapid screening of a large number of plants, as well as for making fewer more accurate determinations. Ten varieties of kale and five of forage rape were grown on experimental plots and harvested at intervals between August and January. The SMCO content of the plants increased as they matured and secondary growth began. The flowers of kale contained twice as much SMCO per unit weight as the whole plant and were very toxic to cattle. Varietal differences in SMCO content were found in plants analysed before the onset of secondary growth, Maris Kestrel and Cauletta showing lower values than other varieties. Substantial amounts of SMCO were found in swedes, both in the “roots” and the “tops”, each structure being toxic to cattle. Other brassicas examined included Chinese cabbages, turnips, fodder radish and a Raphanobrassica .