AVERMECTIN-B1A IN CELERY - ACETONE-UNEXTRACTABLE RESIDUES

Stalk and leaf samples of celery treated with radiolabeled avermectin B1a were serially extracted with acetone, MeOH/H2O (40/60), and hot DMSO. Characterization of the residues extractable with acetone has previously been reported. Characterization of the residues extractable by aqueous MeOH and hot DMSO, which solubilizes lignin, demonstrated that the residues were mostly unknown polar degradates of avermectin B1a. In leaves from plants treated with [C-14]- or [H-3]avermectin B1a 18.61 and 15.19%, respectively, of the residue were unextractable after treatment with hot DMSO. In the corresponding stalks 8.78 and 9.82%, respectively, of the residue were unextractable. The C-14- and H-3-labeled nonextractable residue in celery leaves was further hydrolyzed to release glucose. In celery, 4.59 (H-3)-14.54% (C-14) of the acetone-nonextractable label present at the normal harvest interval was incorporated into glucose.