Alpha-Oxidation of Omega-(2:4-Dichlorophenoxy)alkanenitriles and 3-Indolylacetonitrile within Plant Tissues

Abstract

BIOLOGICAL and chemical investigations carried out here on the plant growth-regulating activity of ω-aryloxyalkanecarboxylic acids have established the importance of β-oxidation as a mechanism by which these acids are degraded in plants¹. As a logical extension of this work, the corresponding nitriles were prepared and examined in the wheat cylinder elongation test (Table 1, Fig. 1) and pea curvature test (Table 1). Extracts of the wheat and pea tissues and of the solutions used in these tests were then separately examined by paper chromatography in the descending manner using butanol/ammonia/water (200:6:36 at 20° C.). The chromatograms were divided transversely into ten equal segments and each was assayed for growth-regulating activity by the wheat test. Authentic 2 : 4-dichlorophenoxy-acetic acid was also run in each experiment. By such means it was possible to correlate activity of the substance originally tested with the production of the dichlorophenoxyacetic acid, a compound highly active in the wheat cylinder test. In every instance where growth-regulating activity was shown, chrom-atographic evidence for degradation of the compound to 2:4-dichlorophenoxyacetic acid was obtained. Thus, when the homologous series of acids used in these experiments (RO(CH₂)_nCOOH) was treated with both wheat and pea tissue, an alternation in activity associated with β-oxidation¹ was accompanied by the appearance of 2:4-dichlorophenoxy-acetic acid when n was 1, 3 and 5.