Abstract
The first preparation of crystalline ovarian hormone 1 was obtained from a combination of 2 acidic aqueous solutions containing approximately 7500 rat units of a potency exceeding 1000 units per mgm. The aqueous solution (volume 480 cc.) was extracted with six 150 cc. portions of ethyl ether, the ether distilled and the flask evacuated to remove the last of the solvents. The residue was leached with small volumes of anhydrous ethyl ether, this solution centrifuged, poured into a flask and distilled to dryness. Owing to the danger of ether peroxides 1 cc. of ethyl alcohol was added and distilled using a vacuum to complete the removal of the alcohol. The flask was put in the refrigerator (-10° C.) and crystals began to appear within a short time. The weight of the crystals, which possibly were not absolutely pure, was 2.07 mg. Upon an additional purification the weight diminished to 1.39 mg.
Beginning with this initial crystallization, we have been able to convert all of our preparations into a crystalline form. Many individual preparations have been converted into the pure crystals. Several other products of a different crystalline form isolated during the course of preparation have proved to be inactive upon assay.
One interesting observation regarding the crystalline structure has been made. The pure hormone crystallizes in at least 2 distinct forms of crystals, a phenomenon which is not exceptional but which is encountered quite frequently.
For want of a more adequate description, we refer to the one form as clusters of needles (A) and to the other as rhombohedral plates (B). In one of our earlier preparations, A separated from a light yellow oil. Upon washing out the oil with cold ethyl alcohol, we obtained the A form apparently in a pure condition.
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