Certain Factors in the Preparation of Cortin. ∗

Abstract

The potency of the extracts used in this study has been tested by the effect on the growth of young adrenalectomized white rats. 1 This test has been carried out immediately after adrenalectomy as that is the most crucial period of adrenal insufficiency. Sometimes when the animals have failed to grow they have been further tested by their resistance to cold, 2 comparison being made with adrenalectomized rats treated with adequate cortin.

In an earlier work on the hormone of the adrenal cortex in which it was salted out with the globulins 3 we found that exposure of the precipitate to air for a few hours reduced the potency. Moreover heating the extract of the sodium chloride precipitate to 8o°C. for 5 min. with stirring, to cause admixture with air, destroyed the hormone. 4 From this evidence we concluded that it was necessary to operate in the absence of O₂. Distillation of the ether at atmospheric pressure in the preparation by the ether-alcohol method 4 produces a less potent extract than when the distillation is in vacuo. Heating the concentrated extract in an open beaker for one hour at 80°C. without stirring does not appreciably destroy the hormone. The extract can be boiled for a short period (5 minutes) in the absence of oxygen without great loss of potency.

Small amounts of antioxidants, such as hydroquinone, resorcinol or levulose retard the loss of potency in aqueous solution. The hormone can be preserved in 80-9570 alcohol for weeks. Cortin is very unstable in the presence of the fixed alkalies. It seems to be completely destroyed by tenth normal NaOH at 20°C. in less than one hour.