Transformation of N',N'-dimethyl-N-(hydroxyphenyl)ureas was assayed in the presence of purified laccase produced by the fungus Trametes versicolor. The para-and orthohydroxyphenyl derivatives were enzymatically transformed, whereas the meta derivative was not.The performance of laccase-mediated transformation depended on the pH with an optimum for the para-derivative degradation rate at pH 5. The pH also influenced the nature of the reaction products. The chemical was exclusively oxidised into p-benzoquinone at pH 3 and into mainly N',N'-dimethyl-N-[(2,5-cyclohexadiene-1-one)-4-ylidene]urea at pH 6. The ortho-derivative was transformed essentially into insoluble purple compounds, probably appearing as polymers resulting from coupling of the parent compound.
275W e have found previously that two 5-acetyl-4-methylpyrimidines could be transformed by aminoguanidine hydrochloride into 4-acetyl-1-amidino-3-methylpyrazolyl amidinohydrazone dihydrochloride. This reaction beside the fact that it led to a molecule closely related to the antitumor drug M.G.B.G. pointed out to a new possibility of ring contraction of pyrimidines into pyrazoles. We attempted therefore to study the possibility of extending this transformation to other substituted hydrazines and to define more accurately the conditions of this reaction as well as to prepare new potential anticancer drugs.J. Heterocyclic Chem., 23, 275 (1986).Among anticancer drugs mitoguazone or methylglyoxalbis(guany1hydrazone) (MGBG) [ l ] has the striking feature of being structurally related to spermidine [2], and is a good inhibitor of the enzyme S-adenosylmethioninedecarboxylase (SAMD) [3].
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