MUTAGENICITY OF THE NATURALLY OCCURRING CARCINOGEN CYCASIN AND SYNTHETIC METHYLAZOXYMETHANOL CONJUGATES IN SALMONELLA-TYPHIMURIUM

  • 1 January 1979
    • journal article
    • research article
    • Vol. 39  (9) , 3780-3782
Abstract
The aglycone methylazoxymethanol of the naturally occurring carcinogenic glucoside, cycasin [from Cyeas circinalis and C. revoluta], was previously shown to be mutagenic but cycasin per se was not. Cycasin was demonstrated to be mutagenic using a modification of the Ames Salmonella test [involving use of a rat liver microsomal preparation] in which it was preincubated with .beta.-glucosidase and the tester strain in liquid medium. The mutagenicity of cycasin to 6 histidine-dependent Salmonella strains varied considerably with strain HisG46 being the most susceptible. Methylazoxymethyl-.beta.-D-glucosiduronic acid, which also is nonmutagenic per se, similarly became mutagenic when preincubated with .beta.-glucuronidase. Methylazoxymethyl acetate, which is slightly mutagenic by the Ames standard pour plate method, became highly mutagenic on preincubation. The mutagenicity of free methylazoxymethanol was confirmed and a linear dose-response relationship was observed. The common conditions required for activation of nonmutagenic methylazoxymethanol conjugates, the glucoside cycasin and methylazoxymethyl-.beta.-D-glucosiduronic acid, are 90-min preincubation at 30.degree. C, pH 6.5, with an appropriate hydrolase and Salmonella typhimurium HisG46.

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