Activity and properties of para-aminobenzyl penicillin.

Eagle (1947a) has shown that p-hydroxybenzyl penicillin (X) was more effective than benzyl penicillin (G) in curing mice infected with Streptococcus pyogenes and Streptococcus pneumoniae. Hewitt and Pittman (1946) have obtained similar results in animals infected with Hemophilus influenzae. It was further shown that penicillin X remains in the blood of human subjects longer than penicillins G or K (Eagle, 1947b). It may be seen from these experiments that penicillins X and G differ in their therapeutic usefulness. The introduction of the phenolic hydroxyl group in benzyl penicillin to give rise to penicillin X is accompanied by increased water solubility (Clarke et al., 1949a). This property is also reflected in the paper chromatographic behavior; that is, penicillin X has a relatively low Rf value compared to those for penicillins G, F, dihydro F, and K (Karnovsky and Johnson, 1949). In this study a penicillin more hydrophilic than penicillin X was sought for a comparison with penicillin G. For this purpose a group of compounds were tested for their ability to act as precursors for such a penicillin. In order to facilitate the selection of the proper precursor a paper chromatographic method was employed. Of the several precursors tested, only five produced penicillins with a lower Rf value than that of penicillin X. Among these, p-aminobenzyl penicillin was chosen for the work described in this paper. Although the formation of this penicillin has been reported previously (Corse et al., 1948; Clarke et al., 1949b), its properties or partial purification have not been described.