The antiseptic action of ethoxyquinolin,chitenin and H-acid

Abstract

In 1911 Morgenroth and his collaborators 1 found that when hydrocuprein, a quinine derivative, was changed to ethyl hydrocuprein the substance acquired specific pneumococcicidal powers, both in vitro and in vivo. However, many clinicians have found that in the treatment of lobar pneumonia ethyl hydrocuprein is too toxic and that changes in the optic nerve and sometimes permanent blindness may result from its use.

Two years ago Pankow and Hirschfelder 2 investigated two parallel series of simple aromatic substances, hydroxy compounds and the corresponding ethoxy compounds, in order to determine whether in these simple compounds also, the introduction of an ethoxy group would yield increased pneumococcicidal action. The experiments showed, however, that this is not the case. In the series reported in this paper we have tested the action of 8-oxyquinolin sulphate

A few loopfuls of pneumococcus suspension were added to the solution of the substance in 0.9 per cent. NaC1, and after the desired interval transpired to rabbit blood agar plates and incubated 24 hours. We find that, like the aromatic compounds, there is practically no difference in the action of the two compounds upon the pneumococcus. A ten-minute exposure to 1 / 5 0 solution in 0.9 NaCl kills the cocci. The streptococcus is less sensitive requiring a 1/1000 solution, but no difference is observable between the two compounds.

An attempt was made to produce a quinine derivative having a toxicitiy less than quinine. Chitenin, which differs from quinine in having a -COOH group in place of the vinyl -CH=CH₂ group in the side chain was prepared by oxidizing quinine according to the method of Skraup 3 . We have found that this substance is from three to four times less toxic than quinine on subcutaneous injection (minimum lethal dose of Chitenin=2.2^G to 4.2^G per Kg. rat; minimum lethal dose of quinine =0.7^G per Kg. rat).