METABOLISM OF 4-NITROPHENOL IN SOYBEAN EXCISED LEAVES AND CELL-SUSPENSION CULTURES OF SOYBEAN AND WHEAT

The metabolism of 4-nitrophenol was studied in cell supension cultures of soybean (Glycine max) and wheat (Triticum aestivum), and in excise d leaves of soybean. Results obtained from these three systems were ap proximately similar; 4-nitrophenol was transformed almost quantitative ly (turnover rate > 85 %) to chiefly more polar soluble conjugates bes ides minor amounts of non-extractable residues (approx. 5 %). The pola r compounds were identified with 1(O-beta-D-glucopyranosyl)-4-nitroben zene and O-malonyl-O-beta-D-glucopyranosyl)-4-nitrobenzene. Glucosylat ion of 4-nitrophenol and subsequent malonylation of the conjugate may be regarded as further evidence of the hypothesis that malonylated glu cosides are end products or at least long-lived intermediates of xenob iotic metabolism. The unexpected low percentages of non-extractable re sidues indicate that either plants are endowed with different mechanis ms/pathways resulting in insoluble residues, or there is a competition between glucosidation and formation of bound residues.