The reduction of the 4, 5 double bond of steroids by bovine blood proteins.

During our study of the hydrolysis of steroid acetates by bovine blood albumin, it was observed that, if cortisone acetate was transferred to the incubation medium with acetone, the ultraviolet absorption at 240 rnp was completely lost in 24 hours. A survey of the literature showed that the conjugated system might have been destroyed by enzymatic reduction of the double bond or the 3-keto group (1, 2). Since Dorfman has recently reviewed this subject (3), reports on the reduction of the double bond in ring A by enzymes of liver will not be discussed. However, in connection with our observations on reduction of the double bond by bovine albumin, it is interesting that Meyer found destruction of the conjugated system in ring A of cortisone during perfusion of the adrenal with whole blood and by incubation of cortisone with whole blood (4), and Wotiz et al. (5) reported a decrease in ultraviolet absorption at 240 rnp on incubation of testosterone with human serum. We reported previously that, if the propylene glycol concentration was reduced from 20 to 3 per cent in incubation mixtures designed for the study of hydrolysis of acetates of adrenal cortical steroids by bovine blood albumin, the ultraviolet absorption at 240 rnp of steroids disappeared (6). Subsequently, it was reported that this loss of absorption at 240 rnp was due to enzymatic reduction of the double bond in ring A (7) ; this paper is a continuation of the study of the reducing activity of the bovine blood albumin preparation.