Does the introduction of an ethoxy group into aromatic compounds increase their bactericidal action upon the pneumococcus and the gonococcus? 1

Abstract

Morgenroth and his collaborators have shown that when an ethoxy group is substituted for the methoxy group in quinine derivatives and ethylhydrocuprein is produced, the substance takes on markedly increased pneumococcicidal action in vitro and in vivo. Solis Cohen, Kolmer and Heist found that ethylhydrocuprein hydrochloride was from eight to twenty times as strong an antiseptic for the pneumococcus as quinine hydrochloride. Morgenroth and Levy had shown that no such difference between quinine and ethyl hydrocuprein could be observed in the case of the streptococcus. We find that when cultures of gonococcus are exposed to starch bouillon containing quinine hydrochloride or ethylhydrocuprein in 1/10,000 dilution and then transferred to plates of rabbit's blood agar, growth occurs if the exposure to the drug has lasted only ten minutes but the bacteria are killed if the exposure has lasted thirty minutes. Ethylhydrocuprein has therefore no specific action against the gonococcus. However, as ethylhydrocuprein is too toxic for successful use in the chemotherapy of lobar pnuemonia, substances which are less toxic must be sought for.

The first question to be determined is whether pneumococcicidal properties are common to ethoxy compounds in general or whether this property is peculiar to ethylhydrocuprein and its closely related compounds. We have accordingly tested the bactericidal action of the ethyl ethers of various aromatic compounds, and compared them with the corresponding hydroxy compounds. In making the tests a suspension of pneumococcus type I. from the Rockefeller Institute was suspended for the desired interval in a broth solution of 0.9 per cent. NaCl containing the substance whose action was to be determined; and after the desired interval a loopful of this stroked across a rabbit's blood agar plate and incubated 24 hours.