Twenty-one selected compounds derived severally from benzene, naphthalene, acenaphthene, phenanthrene and isoquinoline have been examined for their pressor activities in the spinal cat, using tyramine as the control.
The α-naphthyl methylamines resemble benzylamine in exhibiting feeble activities. Fair degrees of activity are shown by the ω-amino aceto-naphthones, the β-naphthyl ethanolamines and the β-naphthyl ethylamines. The rules governing the qualitative and quantitative relation between structure and pressor action of benzenoid sympathomimetics seem to apply to members of the naphthalene series only to a limited extent. The substitution of the benzene nucleus of pressor bases by the naphthalene ring generally results in considerable increased activity, but this has an exception. Consequently, the generalisation of Madinaveitia that such substitution augments the activity by over forty times receives only limited support. The postulate of von Braun that methyl amino hydrindene owed its intense activity to its being doubly a β-phenyl ethylamine appears inadequate in view of the low activity evinced by a number of bases which may be considered as β-phenyl ethylamines many times over. While the naphthalane and acenaphthene nuclei are equal and about seven times as effective as the benzene ring the phenanthrene ring is only twice as effective. New potent pressors appear unlikely to be encountered in the benzene, phenanthrene and isoquinoline ring systems, but the naphthalene series seems to be promising.