Another sulfur compound, so called "sulfurized oil," in which sulfur and fatty acids appear to form a hydropersulfide, (Note 7) was tested. This hydropersulfide preparation, although it exhibited no influence upon viruses in vitro, did induce a good degree of local resistance of the skin to smallpox infection. The effects upon microbes were reduced. There was little direct influence exerted upon cells. The preparations with 0.5 to 1% sulfur bound to cottonseed oil were well tolerated locally when administered intramuscularly or intraperitoneally.

The effect of parenteral and oral hydropersulfide upon pain was slow to appear, in contrast to the effect of fatty acids and even of mercaptans. However, it persisted for a long time. Pain of the acid pattern was eased; pain of alkaline pattern was exacerbated. The influence upon the second day wound crust pH was marked. The local pH increased to values even higher than 7.80. In radiation lesions, the dimension of ulceration increased and healing was retarded or even prevented. In some tumors in animals, the rate of growth was slowed. This latter effect was not uniform in the different types of tumors tested and even in the same type of tumor in different groups of animals. Systemic changes also varied. Doses corresponding to 5 mgr. of sulfur were not toxic for 30 gm. mice in a single injection. Nor were 15 mgr. doses in 200 gr. rats. Chronic toxicity studies showed that 0.2 mgr. daily injections in mice and 5 mgr. injections in rats for as long as three months did not induce pathological changes. High doses such as 1 to 2 cc. of a 1 % preparation injected several times a day in humans was almost uniformly followed by a rise in temperature, usually after a few days.

Other Compounds With A Thiol Group

The results obtained with hydropersulfide preparations led us to seek other compounds with sulfur bound to fatty acids instead of triglycerides as in those mentioned above.

Sulfur compounds were prepared from various conjugated fatty acids such as conjugated linoleic acid and eleostearic acids and from mixtures of conjugated fatty acids obtained from cod liver oil, fish oil, human placenta, blood and various organs. While active in smaller amounts, they were not qualitatively different from hydropersulfide preparations obtained from cottonseed oil, producing the same pharmacological effects in most tests, especially upon pain, systemic manifestation and evolution of experimental tumors.

The fact that sulfur bound to the nonpolar group, as in hydropersulfides, produced less manifest results in animals and humans than mercaptans, which have a thiol group as a polar group, led to the study of other substances in which thiol radicals instead of sulfur were added in similar positions, and consequently were considered to act as secondary energetic groups. A series of preparations, in which one or more thiol groups were fixed at the double bonded carbons in various conjugated or nonconjugated polyunsaturated fatty acids, were obtained. These substances differ fundamentally from the fatty acids mentioned above in which sulfur atoms were fixed not at the carbons bound by double bonds but at the carbon adjacent to the double bond. 9-10, dithiostearic acid, 9, 10, 12, 13, tetrathiostearic acid, as well as polyunsaturated and conjugated fatty acids with thiol groups fixed at their double bonds, were obtained. In general, they showed no marked biological effects on animals, no influence upon pain or systemic patterns similar to those observed for the other lipidic products with bivalent sulfur.

The hydropersulfide group was added to soaps. Sodium and ammonium soaps were obtained through saponification of the triglycerides of fatty acids on which sulfur was already fixed. Effects at the different levels of organization were markedly reduced. There was no influence upon pain, organic or systemic manifestations. However, a striking effect was noted on many microbes. Growth of Bac. anthracis was prevented in some experiments, even with dilutions of 1/2,000,000. For staphylococcus aureus and streptococcus hemolyticus, a similar effect was obtained with dilutions higher than 1/200,000. In animals, even oral administration in drinking water in a dilution of 1/500 and, in some experiments even 1/1000, controlled infection caused by these microbes. The antibiotic activity appeared to be similar to that of penicillin. (Note 8)

Tetrahydronaphthalene Persulfides (Sulfurized Tetraline)

We utilized the known marked tendency of tetrahydronaphthalene to fix oxygen with the resulting explosive peroxides, to fix sulfur in similar combinations. Persulfides of this substance were thus obtained and their pharmacological activity studied. While only a limited effect was noted upon viruses and microbes, the influence upon tetrahymena pyriformis approached that seen with active polyunsaturated fatty acids. The product with 5 gm. sulfur fixed for 100 grams of tetrahydronaphthalene, showed a relatively low toxicity in normal animals, 75 mgr./100 gr. in mice and 125 mgr./100 gr. in rats being well tolerated in intraperitoneal administration. The influence upon wound healing in animals, upon pain, and upon the systemic analyses in humans, was similar to that seen for the mercaptans. Although the immediate effect on pain was limited, prolonged administration was effective. The analytical changes of the urinary surface tension and blood potassium were the most manifest. The toxicity was highly increased for animals with ascites tumors (Sa 180, Ehrlich and Krebs). However, the influence exerted upon transplanted and spontaneous tumors in animals was one of the most favorable ones, compared to the effect of other tested agents.