Walter R. Benson

THE CHEMISTRY OF PESTICIDES

This review is limited to the structures and a few reactions of the pesticidesmainly imecticides-that affect mammalian systems and that are the subject of papers by other authors in this monograph. There is no attempt to give a complete review of the chemistry of pesticides. It is intended only to show the breadth and depth of pesticide chemistry through the use of examples. With proper use of the references, and of the papers by Crosby, Freed and Montgomery, and Owens in this monograph, the reader will be able to find information for other chemicals. NOMENCLATURE

SPECTROPHOTOMETRIC STUDY OF DIENESTROL PHOTOISOMERIZATION

Abstract— Photolysis of synthetic estrogen dienestrol resulted in formation of a 4a,4b‐dihydrophenanthrene, a rare example of a stable intermediate of the classical stilbene → phenanthrene photocyclization. Time‐lapse spectrometric investigation suggested an initial cis‐trans isomerization in the dimethylbuta‐dime moiety of dienestrol followed by a photochemical [1, 51 sigmatropic proton transfer which converted the two cross‐conjugated p‐hydroxystyrene halves into a vinyl‐stilbene. A subsequent electrocyclic ring‐closure in an electronically excited state generated a cyclic nonaromatic heptenediol. This last photoproduct tautomerized rapidly in the dark to a stable, crystalline, tricyclic pentenedione. The final diketone product is an example of a 4a.4b‐dihydrophenanthrene self‐stabilized by a double ketoenol tautomerism. The three sequential photoisomerizations of dienestrol are made possible by a fortuitous coincidence of steric and orbital symmetry requirements.

Two components of laetrile (mandelonitrile and cyanide) stimulate guanylate cyclase activity.

Summary The effect of four components of laetrile (mandelonitrile, amygdalin, cyanide, and a neoamygdalin-amygdalin mixture) on guanylate cyclase activity in a variety of tissues was examined. Mandelonitrile and cyanide, which can be released from mandelonitrile, stimulated the activity of rat guanylate cyclase (EC 4.6.1.2), an enzyme thought to be important in normal and abnormal cell growth, Amygdalin and neoamygdalin had no effect in these same tissues. The activation of guanylate cyclase by mandelonitrile was observed over the concentration range 0.001 to 3 mM, while cyanide stimulated the activity of guanylate cyclase in concentrations of 0.1 to 3 mM. Since many nitrosamine and nitrosamide carcinogens also stimulate guanylate cyclase activity, the present investigation suggests that possible carcinogenicity of laetrile used in man needs further study.