Fate of [14C]emamectin benzoate in cabbage. 2. Unextractable residues.

摘要

Cabbage plants were treated in the field with 7 weekly applications of [14C]emamectin benzoate followed by a final application of [14C/3H]emamectin benzoate at two rates; the maximum expected commercial use rate of 0.015 lb a.i./acre and 0.075 lb a.i./acre. Methanol homogenates of cabbage heads were extracted with methanol/water containing ammonium acetate. Approximately 14-26% of the total residues remained unextractable. The unextractable residues were characterized by serial treatment with buffer, cellulase, alpha-amylase, pectinase [polygalacturonase], and proteinase, solubilization with hot dimethyl sulfoxide, and reflux with 0.5 N sodium hydroxide. A portion of the amylase hydrolysate was treated with maltase. All samples were analysed for radioactivity. Selected fractions were assayed for glucose and protein. Generally, recovered radioactivity was released in the following order: proteinase (23-29%) > dimethyl sulfoxide (15-29%) > NaOH (12-18%) > cellulase (9-17%) > buffer (9-16%) > alpha-amylase (7-9%) > pectinase (3-5%). Only about 1% of the initial unextractable residues remained uncharacterized after the procedure. Incorporation of radioactivity into natural products, such as protein, cellulose, lignin, and starch, is suggested.