Spirobutyrolactone Aldosterone Antagonists

Aldosterone, essentially a corticosteroid in which the methyl group at Cjg is oxidized to a carboxaldehyde, was the last endogenous steroid to be isolated in a form suitable for structural studies. This hormone controls via its action on the kidney both body electrolyte balance and blood volume. A number of modified androstanes, all of which feamre a spirobutyrolactone at C17, act as aldosterone antagonists Those 17-spirobutyrolactones consequently show diuretic and 

36-4 the hydroxyl group at C3 is acetylated in the process (36-4). Hydrolysis of the acetate followed by Oppenauer oxidation then affords the prototype aldosterone antagonist spirolactone (36-6). 

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A small set of steroids prepared from androstanes feature a spirobutyrolactone at C17. These agents act as antagonists of aldosterone, the highly oxygenated steroid that controls serum electrolytes and blood volume. The antagonist action of the spirolactones is manifested as diuretic and antihypertensive activity. 

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