Parasiticidal Potencies of the Tri- to Hepta-Methyl Derivatives of Rosanilin.

Faust and Yao 1 have shown that gentian violet, either by oral or by intravenous injection, is parasiticidal for Clonorchis sinensis, a fluke residing in the biliary passages of man, dogs and cats in the Far East. Although in chronic cases of long standing the flukes are at times so effectively walled off by the thickening of the biliary epithelium that it is impossible for the dye to reach them in lethal amounts, from 60 to 95% of the flukes can be destroyed by this dye, thus producing material improvement in the patient. Olivier and Kandou, 2 utilizing gentian violet therapy on 18 Clonorchis-infected patients in Java, have been able to confirm the results of Faust and Yao. It has seemed desirable, therefore, to follow the experimental work a step further in order to determine (1) which homologs in the methylated rosanilin series possess the parasiticidal properties and, if possible, (2) the portion of the potent homologs which is responsible for the results. With this in view the following dyes were obtained and the bactericidal and clonorchicidal potencies tested.

1. Dahlia crystals, e. g., tri-methyl rosanilin (National Aniline and Chemical Co., and Grübler).

2. Gentian violet crystals, e. g., a half and half combination of tetra-, penta-, and hexa-methyl pararosanilins with dextrin. (N.A. CC).

3. Enteric coated gentian violet pills (N.A.C.C.).

4. Methyl violet B crystals, e. g., about 8% tetramethyl, 80% penta-methyl and 12% hexa-methyl pararosanilin. (N.A.C.C.).

5. Crystal violet crystals, e. g., pure hexa-methyl para-rosanilin. (N.A.C.C).

6. Methyl green, e. g., hepta-methyl pararosanilin. (Grübler.)

Table I shows the relative bactericidal potencies of the several dyes at different dilutions.

It will be seen that crystal violet is the only member of the series which conforms to the biological specification of the Commission on the Standardization of Biological Stains (Conn 3 ), namely that it should have “sufficient bacterostatic power so that, when added to nutrient agar in the proportion of one part to a million, it will entirely prevent the growth of Bacillus subtilis when this organism is streaked over the surface of the hardened agar.”