Identification of biologically active natural spirolactone derivatives in man and animal

For the first time, the presence of three natural spirolactones hydroxylated at C6C7 (6 alpha, 7 alpha-, 6 beta, 7 alpha- and 6 beta, 7 beta-dihydroxy-6,7-dihydrocanrenone (DHC) is demonstrated in man and in animal urine (rat, dog, sheep), and possibly in the blood. The existence of the fourth isomer 6 alpha, 7 beta- is also possible. Salt-loading in man and the rat results in a decrease in urinary 6 alpha, 7 alpha- and 6 beta, 7 beta-DHC. Salt-depletion increases their urinary concentration in the rat. DHC isomers are not found in the urine of adrenalectomized rats. Injected into the caudal vein of the rat, both 6 alpha, 7 alpha- and 6 beta, 7 beta-DHC induce a significant retention of Na+. On the other hand, 6 beta, 7 alpha-DHC significantly increases Na+ and K+ excretion. The biological activities of these natural compounds seem to be different from those of synthetic spirolactonic drugs.