The protective effect of sulfur-containing steroids against nephrocalcinosis induced by mercuric chloride in rats.

1. Experiments were conducted on rats and structure-activity correlations were performed using sulfur-containing steroids against nephrocalcinosis induced by mercuric chloride (HgCl2). 2. The protective effect of spironolactone has been described previously and we have now demonstrated the activity of 7-mercapto-17-hydroxy-3-oxo-4-androsten-17-propionic acid-lactone. 3. The activity of the sulfhydryl radical present in this molecule has been shown to be slightly lower than that of the thioacetyl radical present in spironolactone. 4. The importance of the steroid structure to which a specific radical is attached has become evident during these experiments with the inactivity of 7-mercapto-3,20-dioxo-4-pregnene-16-carbothiamineacetate which possesses a thioacetyl group in the same position as spironolactone (i.e. only the two lateral chains in position 16 and 17 are different between these two steroids). 5. Thus, both the composition of the sulfur-containing radical and the steroid moiety are important for protection against inorganic mercury poisoning.