Antibacterial action of a reaction product of cysteine and iron. II. Preparation and properties of the substance.

Abstract

It has been shown that when low concentrations of cysteine and ferric ammonium citrate or other ferric salts in distilled water, adjusted to faintly acid reaction, are repeatedly autoclaved, an insoluble granular precipitate forms. Chemical analysis of the precipitate indicates that it is sulphur. X-ray photographs of the precipitate and orthorhombic colloidal sulphur, while showing broadly similar patterns, possess significant differences which indicate that the precipitate has a lower symmetry or larger unit cell in its arrangement of sulphur atoms than has orthorhombic sulphur. This precipitate added to Dubos' medium in concentrations of 0.5 to 4 μgm. per ml. inhibits growth of M. tuberculosis. In a concentration of 10 μgm. per ml. growth of all of four other Gram positive species of bacteria and three of five Gram negative species was inhibited. Colloidal sulphur had a similar growth inhibiting property but larger concentrations were required than of the precipitate prepared from cysteine and iron.