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 excised leaves of soybean. Results obtained from these three systems were approximately similar; 4-nitrophenol was transformed almost quantitatively (turnover rate > 85 %) to chiefly more polar soluble conjugates besides minor amounts of non-extractable residues (approx. 5 %). The polar compounds were identified with 1(O-beta-D-glucopyranosyl)-4-nitrobenzene and 1(6'-O-malonyl-O-beta-D-glucopyranosyl)-4-nitrobenzene. Glucosylation of 4-nitrophenol and subsequent malonylation of the conjugate may be regarded as further evidence of the hypothesis that malonylated glucosides are end products or at least long-lived intermediates of xenobiotic metabolism. The unexpected low percentages of non-extractable residues indicate that either plants are endowed with different mechanisms/pathways resulting in insoluble residues, or there is a competition between glucosidation and formation of bound residues.