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Therapeutic activity of pretazettine on Rauscher leukemia: comparison with the related Amaryllidaceae alkaloids.

Comparative studies on the cytotoxicity and antileukemic activity of limited numbers of Amaryllidaceae alkaloids with pretazettine, a narcissus alkaloid, have been performed on the systems of Rauscher virus-carrier cells and the leukemic mice. Only precriwelline, a stereochemical epimer of pretazettine, has been found to be therapeutically active as that of pretazettine. The natural precursors such as haemanthamine, crinamine and 6-hydroxycrinamide were also moderately active, but the artificial final product, tazettine, was confirmed to be inert. The structure-activity relationship of pretazettine or precriwelline has been partially analyzed. Also, the predominancy of antiviral activity relative to cytotoxicity of the alkaloids has been demonstrated when compared with some standard antileukemic drugs.