The highly selective, enzyme-activated, irreversible inhibitor of L-ornithine decarboxylase, DL-alpha-difluoromethylornithine, suppresses the increase in uterine L-ornithine decarboxylase activity associated with early embryogenesis in the mouse and arrests embryonic development at that stage. Contragestational effects were confirmed in the rat and rabbit. An increase in L-ornithine decarboxylase activity that leads to a rapid increase in putrescine concentration appears to be essential during a critical period after implantation for continued mammalian embryonal growth.

A series of tetraamines derived from 1,8-diaminooctane was prepared and tested as antitumor agents. The reaction of 1,8-diaminooctane with acrylonitrile gave N,N'-bis(cyanoethyl)-1,8-diaminooctane, which was reduced to tetraamine 20. Alkylation of the terminal nitrogen atoms of the tetra-Boc derivative of this compound by methyl or ethyl halide followed by removal of the Boc groups gave the bis(alkyl)polyamines 26a and 26b, respectively. These three compounds exhibit promising antitumor activity in the mouse L1210 leukemia model. Coadministration of a polyamine oxidase inhibitor potentiated the antitumor activity.

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