Biological and chemical properties of the epidioxide isomer of abscisic Acid and its rearrangement products.
The growth inhibitory activity of the epidioxide (II), a precursor in the synthesis of abscisic acid (ABA), has been confirmed with additional assay systems. Under physiological conditions the epidioxide is rearranged to give ABA and an isomer of ABA which has probably the structure V. This major product has very low, if any, biological activity. The biological activity of the epidioxide is explained by its partial conversion (about 20%) to ABA. The reaction rate was enhanced by heavy metal ions and decreased by EDTA. At pH 12.5, the decomposition of the epidioxide is slower than it is near neutrality and ABA is the predominant product. In the biological systems studied the activity of the epidioxide can be accounted for by nonenzymatic conversion to ABA.
Sondheimer
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Chemistry Department, State University College of Forestry, at Syracuse University, Syracuse, New York 13210.
Michniewicz
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BM
Powell
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