The preparation on a microgram scale of some derivatives of aldosterone: their use in paper chromatography.

In order to identify a substance by means of paper chromatography it is highly desirable to compare the running rates of as many of its derivatives as possible with the running rates of comparable derivatives of known substances. When only microgram quantities are available, the preparation of derivatives in good yield often presents a problem. It is the primary purpose of this communication to describe the preparation of three derivatives of aldosterone on a microgram scale and their use to establish the identity of two preparations of crystalline aldosterone and the identity of aldosterone isolated from the “amorphous fraction.” Some bioassay data are also included. Aldosterone (147 7) was acetylated to give 50 y of crystalline 21-acetate, m.p. 193-195”. Simpson and associates (1) reported the melting point as 198-199”; Ham and associates (2) gave 193-196.5”. Another monoacetate, m.p. 217-219”, was described in previous publications (3,4). This acetate now must be regarded as the B-acetate of the ll,lS-lactol structure of aldosterone. The 18,21-diacetate, prepared from 1.6 mg. of aldosterone, could be obtained only in the form of discrete pellets in which a crystalline structure could not be discerned. They melted at about 80”. Simpson and associates (1) gave a melting point of about 70” for the diacetate. These preparations were used for comparison with corresponding preparations derived by similar means from a few micrograms of aldosterone. In a bioassay the activity of the 21-acetate could not be distinguished from that of aldosterone (Fig. 1). Similar results were reported by Ham and associates (2) ; Simpson and associates (1) found 1 y of aldosterone equivalent to 1.25 y of aldosterone al-acetate. Preliminary assays (3, 4) of the 1%monoacetate indicated an activity about 25 times that of deoxycorticosterone acetate, but additional assays showed that that factor should be reduced to about 15. The activity of the 18,21-diacetate proved to be